Boeing 787, N36962

Source: John Richard Thomson

What happened

On 17 April 2016, a Boeing 787-9, registered N36962, operated by United Airlines as flight UAL870, departed Sydney, New South Wales (NSW), for San Francisco, United States. On board were 4 flight crew, 11 cabin crew and 238 passengers. During the departure, cabin crew switched on the aft galley ovens (Figure 1) in preparation for meal services.

After the two ovens were switched on, there was a short burst of smoke, which set off a fire alarm in a nearby toilet for about one minute. One of the ovens displayed a “FAILURE” message. Several cabin crew detected a strong chemical odour and an electrical smell, as well as a blue haze. Other crew described it as an ozone smell. The oven interactive screen displayed a ‘Critical Error- Broken Fuse’ message.

The crew immediately pulled all relevant circuit breakers, and switched off all electrical sources to the aft galley. The inflight service manager (ISM) advised the captain. The ISM and a relief pilot from the cockpit arrived at the aft galley with fire extinguishers. By this stage, the smoke had dissipated, but the odour persisted. As it could not be confidently ascertained that the ovens were the sole source of the problem, the captain contacted the ground-based technical operations maintenance controller (TOMC) by satellite phone.

Figure 1: Rear section of a B787-9 depicting aft galley

Source: SeatGuru modified by the ATSB

The discussion with the TOMC involved all flight crew and the ISM. It was agreed that the safest option was to return the aircraft to Sydney. The captain advised ATC by a PAN^[1] call. ATC initiated an INCERFA^[2] phase. About 110 km east of Port Macquarie, NSW, the crew commenced a return to Sydney. As the aircraft was well in excess of its allowed landing weight, fuel was dumped during the descent.

The aircraft landed without incident in Sydney at 1258 Eastern Standard Time (EST) with emergency services in attendance.

Post-incident engineering report

A post-engineering inspection quarantined the suspect oven, and after an inspection, a fuse was replaced. After appropriate testing, the aircraft was released back to service.

Boeing and the oven manufacturer investigated the cause of the ‘Critical Error’ fault displayed on the oven screen (Figure 2).

The manufacturer individually tested all oven components. They reported that all individual components worked correctly, however, an additional measurement of the oven motor current detected that the motor did not run smoothly. The motor temperature was also above normal, most likely from insufficient airflow. This known fault had been rectified with a new oven software release.

Boeing reported that the oven manufacturer is working with United Airlines to update the software in all relevant ovens in their fleet.

The exact cause of the odour could not be determined.

A second similar occurrence

United Airlines have advised the ATSB of a second similar occurrence involving another B787 aircraft. On 2 June 2016, a United Airlines B787 aircraft, N35953 experienced an electrical/heat odour in the mid B galley. The flight crew dumped excess fuel and returned safely to Melbourne. On this occasion, no emergency was declared.

Maintenance were able to isolate one oven, and confirmed the error was a broken fuse. The oven was removed and replaced, and the aircraft returned to service.

Figure 2: Error message from oven on N35953

ATSB comment

As part of the investigation, the ATSB obtained reports from the flight crew and cabin crew on board during the incident.

It was evident that all emergency procedures were carried out efficiently and effectively. The captain involved all relevant crew members and the TOMC prior to making a decision to return the aircraft to Sydney.

Safety message

This incident highlights the correct management of an abnormal situation with effective crew coordination. Each crew member responded effectively and the situation was professionally managed by the captain.

Aviation Short Investigations Bulletin - Issue 50

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

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1. An internationally recognised radio call announcing an urgency condition which concerns the safety of an aircraft or its occupants but where the flight crew does not require immediate assistance.
2. INCERFA is an uncertain ty phase when doubt exists as to the safety of the aircraft and its occupants

Safety summary

What happened

On the afternoon of 13 January 2016, the roll-on/roll-off passenger ship Spirit of Tasmania II was loading cargo, vehicles and passengers at Station Pier, Melbourne. At 1752, strong wind gusts blew the ship off the wharf and all but two of the ship’s mooring lines (on the bow) parted. After breaking away, the stern swung around until the ship was 90 degrees to the wharf, parallel to nearby Port Melbourne Beach and in danger of grounding. While waiting for tugs to assist, the ship’s propulsion and thrusters were used to maintain its position and prevent grounding. By 1905, the ship was back alongside the wharf, assisted by two tugs.

The ship suffered minor damage to its lower bow ramp and bow doors. Shore infrastructure suffered extensive damage to the elevated roadway and ramp arrangement on the wharf and minor damage to wharf structures. No one was injured.

What the ATSB found

During the afternoon of 13 January, a band of severe thunderstorms passed across the location of Spirit of Tasmania II, with little warning. As the ship’s bridge was unattended throughout the port stay, none of its crew saw indicators of the approaching storm until just before the breakaway.

The ship’s crew responded swiftly. The bridge was manned and machinery was operational by the time the ship had turned 90 degrees to the wharf. The ship’s movement was then controlled using its thrusters and main propulsion until, with tug assistance, it was returned to the wharf.

What's been done as a result

The ship’s managers, TT-Line Company, advised the ATSB that it has implemented immediate changes to shipboard weather monitoring and notification arrangements along with changes to heavy weather and mooring procedures. These changes include: weather triggers for increased shipboard readiness; immediate notification of weather warnings; access to the Bureau of Meteorology (BoM) website from the bridge; changes to the wind speed alarm settings and; requiring all mooring lines to be held on the winch brakes.

TT-Line also engaged external marine consultants to complete extensive investigations and analyses into the mooring requirements and design for Station Pier. The consultants have completed mathematical modelling and incident replication simulations. Subsequent analyses will be used to identify and define operational parameters and recommend any alterations to berthing arrangements and infrastructure. The ATSB has issued one recommendation to TT-Line to complete safety action to adequately address the safety issue with respect to moorings.

The Victorian Ports Corporation (Melbourne) advised the ATSB that Melbourne vessel traffic service will broadcast BoM weather warnings on VHF channel 12. All masters of ships in port waters, including at berth or anchorage, are to ensure a listening watch is maintained at all times.

The BoM advised the ATSB that in addition to verifying the subscription service with the Victorian Ports Corporation (Melbourne) it continues to upgrade its marine weather services. This includes a one-stop webpage on its website for improved education, information and accessibility to marine and ocean services.

Safety message

All ships, especially those with high windage, are prone to breaking away from moorings during short-term events such as thunderstorms and squalls. The risks this presents to ships with large numbers of people on board mean that weather monitoring, mooring systems and procedures need to be regularly checked and verified for changing weather conditions.

The occurrence

At 0600 on 13 January 2016, the roll-on/roll-off passenger ship Spirit of Tasmania II (Figure 1) berthed at Station Pier in the Port of Melbourne. The ship had just completed its usual, scheduled Bass Strait transit from Devonport, Tasmania to Melbourne, Victoria.

Figure 1: Spirit of Tasmania II’s upper and lower bow ramps deployed at Station Pier

Source: Australian Pictorials

A ‘strong wind warning’^[1] for Port Phillip was in effect and had been re-issued at 0527 and 1041 that morning. The warnings noted the risk of afternoon and evening thunderstorms with squalls to 45 knots.^[2] The master was aware of these warnings, and also knew a ‘cold front’^[3] was expected to pass across the port at about 2100 that evening. Departure was scheduled for 1930 and, as a precaution, the master had instructed that two of the ship’s four main engines be ready for manoeuvring at immediate notice from 1600.

After the ship had berthed, unloading of cargo, vehicles and passengers started and continued into the afternoon. As usual, Spirit of Tasmania II was to load cargo and vehicles via its bow, using a lower and an upper vehicle ramp (Figure 1). At about 1600, unloading was completed and the loading of cargo and vehicles started.

The master slept from 1330 onwards to rest for Spirit of Tasmania II’s evening sailing. At 1630, he awoke and attended to some administrative tasks. He also checked the Bureau of Meteorology (BoM) website and noted little change to the weather forecast. At about 1700, when he went to the navigation bridge (bridge), the weather situation appeared normal and as expected. At the time, the wind was about 20 knots from the west and it was cloudy and hot (44°C).

At about 1730, passengers began boarding – those with cars drove on board via the lower vehicle ramp while others boarded via the aft passenger access. The ship’s managers and master had agreed to board the waiting passengers about 30 minutes earlier than usual because it had been a hot day.

It was not until shortly after 1745 that the master returned to his cabin and again checked the BoM website (no internet access was available on the bridge). He saw that a ‘severe thunderstorm warning’^[4] had been issued at 1737. The website indicated a series of thunderstorms approaching Station Pier from about 13 miles^[5] to the west (Figure 2).

Figure 2: Map issued with the severe thunderstorm warning at 1737 on 13 January

Source: Bureau of Meteorology, annotations by ATSB

At about the same time, the second mate (the duty officer) was on the main vehicle deck attending to loading of cars into the main and lower decks. Vehicle traffic had been stopped on the landside of the ship’s bow ramp as traffic had banked up in the vehicle deck.

The second mate noticed a breeze coming in through the open pilot access door in the ship’s side. He called the chief mate via radio and informed him that the wind had picked up, suggesting that the change in weather may have arrived. He closed the passenger door/ramp and pilot access door.

Shortly after, as the master left his cabin to go to the bridge, he saw the wind speed indicator outside his cabin indicated gusts of up to 59 knots. He hurried to the bridge. At 1753, the wind peaked at 60.5 knots (112 km/h) from the southwest (Figure 3). By then, about 120 passengers had boarded and the ship’s stern had started to move off the wharf.

Figure 3: Wind speed and direction, and the ship's rate of turn

Source: Spirit of Tasmania II’s voyage data recorder

With the strong winds pushing the stern away from the wharf, the ship’s aft mooring lines failed in rapid succession. The ship pivoted about its bow and swung away towards the shore (Figure 4).

Figure 4: Section of navigational chart Aus 154 showing the ship’s breakaway

Source: Australian Hydrographic Service with annotations by ATSB (Inset: Google Earth)

On the bridge, Spirit of Tasmania II’s master saw the stern move off the wharf. He telephoned the engine control room but received no response. He then broadcast a message over the ship’s public address system asking an engineer to call the bridge and all crewmembers to go to their mooring stations. The senior engineer in the engine room heard the broadcast, returned to the engine control room, and called the bridge. The master asked for the bow and stern thrusters, followed by two main engines, to be started as quickly as possible.

By 1755, the ship was at an angle of approximately 45 degrees to the wharf and turning away from it (negative rate of turn in Figure 3) at 27°/min.

At 1756, an additional diesel generator was running and the thrusters were ready for use. The engineers then started necessary pumps and by 1758½, two main engines were also ready.

As the ship’s stern came off the wharf, all the aft mooring lines parted. At the bow, the breast line came under tension, but, along with one head line, did not part. The ship pivoted about the bow and its lower bow ramp slid across and dropped off the wharf leaving it hanging over the bulbous bow. As the ship continued to turn, the end of the lower bow ramp swung under the wharf, damaging two wooden piles below the wharf apron.

The upper vehicle ramp detached from the ship’s bow mount and jammed between the bow bulwarks.^[6] As the ship continued to turn, the ramp twisted away from the bow and hung down from its elevated roadway base.

Spirit of Tasmania II’s purser and hotel staff were assisting passengers on board when the ship broke away. The purser became aware of the situation when she heard, and then saw, the aft mooring lines parting and the stern moving off the wharf. She followed the developments and response by listening to the ship’s internal radio traffic. She and her staff assisted passengers, distributed food, drinks and provided reassurance and information as it became available.

By 1759, Spirit of Tasmania II was lying at right angles to Station Pier, parallel to the nearby Port Melbourne Beach. By then, the stern thruster was being used to control the movement of the ship’s stern.

The Port of Melbourne’s vessel traffic service (VTS) had been aware of the strong wind warning and had two tugs standing by throughout the day. One tug was at Webb Dock (about 1 mile to the west of Station Pier) as a precaution to assist a high-sided ship berthed there. The duty VTS officer directed the tug’s master to proceed to the nearby Station Pier to assist Spirit of Tasmania II.

By 1800, the ship’s stern was being held off the beach using the main propulsion (twin screw, variable pitch) and the thrusters (bow and stern).

At 1809, the tug arrived off Spirit of Tasmania II and made fast to the ship’s stern. At 1826, the second standby tug also arrived and began assisting.

By 1900, the wind speed had dropped to about 10 knots and was blowing from the south. At 1905, the ship was again port side alongside Station Pier. It was held alongside using repaired mooring lines and spares, with the tugs assisting. The ship’s engines and thrusters were kept ready for use as required.

Later in the evening, passenger access was restored, and many were accommodated on board for the night. Access to unload vehicles and freight became available the following day.

When Spirit of Tasmania II had turned off the wharf, its starboard bow door had come to rest against the wharf structure. Weight had then come onto it and pushed it against the lower bow ramp, resulting in damage to a number of its door operating components. The hydraulic system used to operate the doors was not damaged. As the lower bow ramp moved off and under the wharf, its end fingers were damaged as they made contact with the wharf piles. The upper vehicle ramp suffered extensive damage (Figure 5) requiring it to be removed from the wharf and taken away for repairs.

Figure 5: Spirit of Tasmania II’s damaged upper bow ramp (skybridge)

Source: TT-Line Company

Inspections and repairs as required by the Australian Maritime Safety Authority, the ship’s flag State authority, and its classification society were then undertaken. On 17 January, 4 days after the incident, Spirit of Tasmania II returned to service.

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1. The Bureau of Meteorology (BoM) defines strong winds as those with a 10-minute average speed between 26 and 33 knots. www.bom.gov.au
2. One knot, or one nautical mile per hour, equals 1.852 kilometres per hour.
3. The boundary between an approaching cool air mass and a warm air mass. The air behind the front is colder, drier and denser than the air preceding it. This cold air pushes under the warm moist air lifting it higher in the atmosphere and can produce cloud, causing rain bands, showers or thunderstorms to form, generally within 100 kilometres of the front.
4. The BoM defines a severe thunderstorm as one that produces, amongst other criteria, damaging wind gusts, generally exceeding 48.6 knots (90 km/h).
5. A nautical mile of 1,852 m.
6. Fore-and-aft vertical plating directly above the upper edge of the ship side surrounding the exposed deck(s).

Context

Spirit of Tasmania II

At the time of the incident, Spirit of Tasmania II was registered in Australia, and owned and managed by TT-Line Company, Australia (TT-Line). The ship was classed with the American Bureau of Shipping (ABS).

Spirit of Tasmania II’s standard mooring line pattern^[7] had been developed for the Station Pier berth (Figure 6). This consisted of three head lines on bights^[8] (numbered 7, 8 and 9 in Figure 6), a spring line (10) and a breast line (11) forward, and three stern lines (1, 2 and 3), two breast lines (4 and 5) and a spring (6) line aft. All mooring lines were 64 mm diameter, mixed synthetic fibre rope,^[9] each with a breaking load of 82 t.

Figure 6: Spirit of Tasmania II’s standard mooring line pattern for Station Pier

Source: TT-Line Company with annotations by ATSB

In Melbourne, the ship loads cargo and vehicles via its bow, using a lower and an upper vehicle ramp. The lower ramp is part of the ship’s equipment and, when deployed, extends out from the main vehicle deck, through the bow doors and onto the wharf. The upper ramp, also known as the skybridge, extends from a raised roadway above the wharf onto the ship’s bow. The skybridge attaches to the ship’s bow via a ball hitch arrangement that accommodates movement of the ship. This provides vehicular access into the upper vehicle decks through the foredeck cargo door.

The ship had a crew of 70 Australians. The master held an Australian master’s certificate of competency and a pilotage exemption for the Port of Melbourne (which includes Port Phillip). He first went to sea as a cadet in 1981, and obtained his master’s certificate of competency in 1994. He had sailed on board Spirit of Tasmania II and its sister ship, Spirit of Tasmania I, since 2002 and first sailed as master of Spirit of Tasmania II in 2004. He had joined the ship about 3 weeks before the incident.

Moorings

A ship’s moorings are intended to keep it safely alongside the berth in the prevailing and expected weather conditions, up to certain limits. Mooring equipment is not designed to be used in extreme conditions. A number of industry organisations publish a range of useful guidance material to assist with effective mooring.

Equipment design

A ship’s mooring equipment, including related machinery and fittings, and its positioning, is determined at the ship design stage. The size, strength and other specifications of various equipment (including mooring ropes, brakes and winches) are based on the ‘equipment number’ or EN. The EN is based on a ship’s size (displacement, beam and height above the waterline)^[10] so that a new ship is outfitted with the appropriate equipment. If circumstances during the ship’s service life change, for example its trading pattern, the mooring equipment, machinery and fittings and how these are arranged on deck may need to be modified.

Other than the EN, there are few other design criteria, rules, regulations or class requirements for mooring equipment. Mooring equipment arrangements are not part of class requirements, other than the sizing of the equipment and the strength of the supporting structure. Class does require a minimum number and size of mooring lines, based upon the ship’s EN, to be used. Mooring equipment must be properly maintained to preserve its design specifications.

Influencing factors

Many of the dynamic factors influencing a ship’s mooring arrangement are weather-related. These include wind, sea and swell along with local factors such as currents, tides and tidal streams. Port and harbour specific factors include berths, channels, other infrastructure and traffic. Many factors interact with and/or influence other factors, for example strong winds can affect currents or streams.

Wind

Wind is one of the most significant factors influencing a berthed ship. The wind force acting on the ship depends on the wind speed and the surface area of its hull exposed to wind (windage). When the wind blows across the berth and towards the water, it will tend to push the ship away from the berth and its moorings will need to withstand the forces imposed.

A simple formula^[11] that gives an approximation of wind loading is:

F = 1.5 x 10^-5 * A * V²      

where    

F is the wind force in tonnes
A is the exposed area in m²
V is wind speed in knots.

Since the wind force varies as the square of the wind speed, small increases in speed translate to large increases in force. In strong winds, gusting amplifies these forces significantly. Strong winds frequently contribute to breakaways.

Sea, swell, currents and tides

The sea and swell acting on a ship’s underwater hull, when sufficiently strong, can cause it to move and impose forces on its moorings. Currents or tidal streams also act on the underwater hull and create lateral forces. The ship’s moorings need to withstand all of these forces.

The height of tide is another important factor as the ship’s hull rises or falls relative to the berth and its mooring lines tighten or slacken. The lines need to be appropriately tended to keep the ship safely alongside.

Port, berth and local factors

The design and location of a port is intended to provide a sheltered area for ships. Some ports have a naturally sheltered harbour, whereas others might need a man-made breakwater at their entrance. Similarly, wharves and jetties are designed to provide appropriate berths for ships. The number and position of bollards and hooks at a berth is an important factor.

Factors such as the proximity of a berth to a shipping channel are important considerations. Passing ships in the channel can interact with a berthed ship and cause it to surge and part its moorings. Ship speeds in channels are limited to eliminate such interaction.

Industry guidance

The Oil Companies International Marine Forum (OCIMF) provides comprehensive industry guidance on mooring in publications such as its Mooring Equipment Guidelines and Effective Mooring. The Nautical Institute provides guidance in two volumes of its Mooring and Anchoring of Ships publication. Together, these publications are the most significant body of research and information on the subject. They are regularly referred to within and outside the oil sector and are accepted as best practice for effective mooring.

The following points summarise some key considerations for effective mooring line patterns described in the publications referred to above:

• optimum load sharing between mooring lines is achieved when lines are loaded to the same percentage of each line’s breaking strength (rather than each line carrying an equal share of the load)
• lines should be of the same material and diameter (lines of differing materials and diameters have different elasticities and will not share additional load evenly)
• lines should be of similar lengths because, as the ship moves off the wharf, the lines will be stretched the same amount which will result in uneven loading in lines of different lengths
• the steeper the angles a line forms with the pier surface and with the parallel side of the ship, the less effective it is in holding the ship against the pier
• mooring winches should be left on the brake once the ship is secured alongside because the brake holding capacity is significantly more than that available in self-tensioning mode^[12]
• if self-tensioning mode is used, it is best used for lines at 90 degrees to the ship’s axis (breast lines)
• sharp bends in a line under load decrease its strength and may cause premature damage or failure
• while running a line as a bight increases its effective holding capacity, if the line parts then two components of the mooring line pattern are lost in a single event
• regular inspection and tending of the mooring lines is required to maintain the mooring effectiveness and counter changes in forces including those due to environmental conditions, tide and draught changes.

The mooring line pattern of a ship will vary significantly with its size and type, port and berth infrastructure, weather and dynamic factors, and effective mooring depends on a range of complementary measures. The pattern should allow for the maximum static load on the moorings with an adequate safety factor to account for expected dynamic factors.

However, certain dynamic situations cannot be easily accounted for by design features or by precautionary measures. For example, when the forces acting on the moorings change suddenly and last longer than it takes the mooring line pattern to respond, a failure becomes more likely. A typical situation is the parting of a mooring line due to a sudden gust in a period of strong winds or surging due to interaction with a large ship passing close at high speed.

The mooring equipment arrangements and mooring line pattern are just two components of effective mooring. Other important considerations include regular tending of mooring lines and effective monitoring of the weather to ensure necessary precautionary measures can be taken in a timely manner. The management of both the ship and the port have a role in effective mooring.

TT-Line Company

The TT-Line Company (TT-Line) has been operating passenger and vehicle ferry services across Bass Strait since 1985. The sister ships Spirit of Tasmania I and Spirit of Tasmania II began service in 2002. Both ships maintain year round, daily, one-way sailings with daily return sailings during the peak summer period. Each ship can carry 1,400 passengers and 500 vehicles. In the 2014-15 financial year, the company’s ships carried 384,501 passengers.

Port of Melbourne

The Port of Melbourne is Australia’s largest container and automotive port. Victorian Ports Corporation (Melbourne) manages the port,^[13] which is located at the northern end of Port Phillip (Figure 7). The port has 36 commercial berths for all types of cargo. In the 2014-15 financial year, the port recorded 3,023 ship visits and handled 87 million tonnes including over 2.58 million containers and 350,000 new motor vehicles.

The Port of Melbourne vessel traffic service (VTS) operates 24-hours a day, 7-days a week, to coordinate the port’s maritime operations.

Figure 7: Melbourne and Port Phillip

Source: Port Phillip Sea Pilots, annotations by ATSB

Station Pier is a historic pier in Port Phillip. Opened in 1854, the pier is Melbourne's primary passenger terminal, servicing interstate ferries and cruise ships. To the east of the pier is Port Melbourne Beach, a popular public beach for residents and visitors.

Weather

The Bureau of Meteorology (BoM) provides weather forecasts, warnings and observations for marine users in coastal and local water areas and high seas off Australia (see Appendix A). Forecasts for wind speed and direction, and sea and swell height are routinely issued every 12 hours. When a wind warning is in force, these forecasts are updated every 6 hours. Wind warnings are issued whenever averaged 10-minute wind speeds are expected to exceed the thresholds for the following categories: strong wind (26 to 33 knots), gale (34 to 47 knots), storm force (48 to 63 knots) and hurricane force (more than 64 knots). Initial warnings aim to provide 24‑hour lead times and are updated every 6 hours.

Weather warnings are broadcast on high frequency radio each hour. The warnings are also broadcast via the maritime SafetyNet satellite communication network when issued and updated at 0400 and 1600. These messages are automatically received and printed on board ships to which SOLAS^[14] applies. All current warnings are posted on the BoM website.

In the absence of severe weather, such as thunderstorms or squalls,^[15] it is normal for wind speed to vary by up to 40 per cent over a 10 minute period. The preamble in all marine forecasts cautions that wind gusts can be 40 per cent higher than the mean wind speed predicted. Stronger gusts are also likely near showers and frontal systems. During thunderstorms or squalls, significantly stronger gusts (higher than the 40 per cent caution) can occur.

In addition to official warnings and marine forecasts, BoM provides a range of weather monitoring tools on its website (see Appendix B). These include tools for accessing weather forecasts as well as weather observations (current and past weather), such as MetEye, weather watch radar and wind forecasting tools. The information displayed by all the tools is to some extent historical as it is based on average data recorded over a period of time and not instantaneous readings. The BoM cautions against using the tools for real-time monitoring and decision-making. These tools cannot be used to accurately monitor short-term weather events such as thunderstorms, squalls and gusts in real time. The intensity of these short duration weather events is also difficult to display historically.

Port Phillip

The weather in Port Phillip is regularly affected by fronts associated with east moving depressions (low pressure weather systems) often centred well south of the coast. On 35 to 40 occasions each year, these depressions create winds of gale force or greater strength offshore. Such weather is more than twice as likely during winter as in summer. While the wind in Port Phillip is less intense than offshore, it can still be significant. Thunderstorms and squalls can also produce strong local winds in Port Phillip and are more frequent in summer (December to February).

In addition to local waters forecasts and wind warnings for Port Phillip, severe thunderstorm warnings for the Melbourne region are particularly relevant to users and the Port of Melbourne. These warnings provide short-term advance warning of severe thunderstorms and are updated every 3 hours. Typically, such warnings are issued on 10 days per year. Squall warnings not associated with thunderstorms are issued on a further 5 or 6 days a year. Sudden wind gusts over 48 knots are experienced often in Port Phillip and a number of weather related incidents have occurred over the years.

Previous incidents

Amongst previous weather related incidents, the two breakaways described below have some similarities to Spirit of Tasmania II’s 2016 breakaway.

2002 - Spirit of Tasmania II

On 13 October 2002, in westerly winds of about 53 knots (98 km/h), Spirit of Tasmania II broke away from Station Pier and turned parallel to the nearby Port Melbourne Beach. At the time, the ship’s two stern lines were made fast to a single wharf bollard. This bollard shifted under the strain causing uneven loading of the mooring lines, which then parted in rapid succession.

Safety action taken by TT-Line after this incident included:

• fitting a wind alarm in the alleyway adjacent to the master’s and deck officers’ cabin
• the ship’s starboard stern fairlead array was altered to allow extra mooring lines to be run
• a new heavy bollard was fitted on the wharf for running of ships’ stern lines.

The mooring line pattern in use on 13 January 2016 was the same pattern that was implemented after the 2002 incident.

Further, this 2002 incident led to a number of procedural changes related to precautions to consider if adverse weather was experienced while berthed. These include:

• monitoring the wind indicator and alarm outside the master’s cabin
• manning the bridge and monitoring weather reports and warnings
• placing the main engines and thrusters on short notice
• closely monitoring mooring lines and equipment
• stopping cargo and passenger operations
• retracting ramps and closing hull doors
• preparing for emergency letting go
• engaging tugs.

2009 - Leyte Spirit

On 21 August 2009, a severe squall with winds of up to 68 knots (126 km/h) passed over the Port of Melbourne causing the crude oil tanker Leyte Spirit to breakaway from its berth.

A safety investigation into the incident^[16] found that the squall line developed very rapidly and, while it was detected by BoM and a warning was issued, neither the terminal nor the tanker received the warning. No appropriate systems were in place to obtain and share local weather information and the investigation recommended that port users develop procedures for obtaining local weather information.

Subsequently, the terminal updated its procedures to ensure that vessels are aware of local weather warnings. The Port of Melbourne Corporation Harbour Master’s Directions^[17] were updated to assist ship masters with obtaining local weather information.

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7. Mooring line pattern is the geometric arrangement of mooring lines between the ship and the berth.
8. A loop formed by doubling back a rope upon itself, effectively doubling the single rope’s restraint capability.
9. Twenty-four strand, 40 per cent polyester, 60 per cent polypropylene/polyethylene rope (KapaFlex 24).
10. EN= ∆²/₃+2×h×B+^A/₁₀ , where ∆ = summer displacement (t), h = effective height (m) of uppermost house above the summer load waterline (LWL), B = moulded breadth (m) and A = area (m²) in profile of hull and superstructures above LWL.
11. Modified from Clark, IC 2009, Mooring and Anchoring Ships, Volume 1: Principles and Practice, The Nautical Institute, London to account for wind speed in knots and provide wind force in tonnes.
12. Self-tensioning (or auto-tensioning) mode refers to a winch setting in which mooring lines are held to a set tension with the winch brake off and the winch motor automatically activated by sensors to drive out or haul in when the line tension differs from the set value. The holding capacity of the winch is then a proportion of its rated pull, not the brake capacity.
13. At the time of the incident the port was managed by the Port of Melbourne Corporation.
14. International Maritime Organisation (IMO), 1974, The International Convention for the Safety of Life at Sea, 1974, as amended (SOLAS), IMO, London.
15. A squall is an abrupt and large increase in wind speed that usually only lasts for minutes then diminishes rather suddenly. The Bureau of Meteorology cautions that ‘the gusts in a squall may exceed 40 or 50 knots…’
16. Office of the Chief Investigator 2009, Breakaway from Berth, MT Leyte Spirit, Gellibrand Pier Melbourne, 21 August 2009, Transport Safety Victoria, Melbourne. Available at http://economicdevelopment.vic.gov.au/chief-investigator/marine-incidents
17. Port manager at the time of this incident. In 2017 this document is published by Victorian Ports Corporation (Melbourne) and is available at www.vicports.vic.gov.au.

Safety analysis

Breakaway

Between 1751 and 1753 on 13 January 2016, the south-westerly wind at Station Pier, Melbourne, increased from about 25 knots to 60 knots. As the wind speed was peaking, Spirit of Tasmania II’s aft mooring lines parted in quick succession and its stern broke away from the Station Pier wharf. As the stern swung away from the wharf, the originally slack forward breast line (11) came under tension and, along with one head line on the bight (9), did not part (Figure 6).

By 1759, the ship lay at right angles to the wharf and parallel to Port Melbourne Beach (Figure 8). While waiting for tugs to assist, the ship’s propulsion was used to maintain its position and prevent grounding. By 1905, the ship was back alongside Station Pier with the two tugs assisting. No one was injured and damage was limited to the ship’s bow ramp and doors.

The sudden and significant increase in wind speed contributed directly to Spirit of Tasmania II’s breakaway. The more than doubling of wind speed increased the wind loading on the ship’s side exponentially (nearly six times). As the buildings on the pier provided least protection from the wind to the shipside area aft, the aft mooring lines took the load first.

As the wind speed was peaking, the ship’s stern moved more than 4 m off the wharf stretching the aft moorings lines. Soon after 1753, the shortest of the stern lines parted. As the ship moved further off the wharf, the load increased on the other stern lines and they quickly parted. The two breast lines were unable to pay out quickly enough and parted. As the ship pivoted about its bow, the forward mooring lines overloaded and parted leaving just two lines intact (Table 1).

Figure 8: Spirit of Tasmania II adjacent to Port Melbourne Beach

Source: George Donikian

Table 1: Sequence and times of lines parting

Weather on 13 January

The weather conditions experienced in Port Phillip on 13 January were consistent with the typical Australian summer weather patterns. The weather systems, including those associated with short-term events such as thunderstorms, regularly develop in the area and were not unusual or extraordinary.

Forecasts

The Port Phillip local waters forecast issued at 1641 on 12 January indicated the possibility of afternoon thunderstorms with squalls up to 45 knots on the following day. The local waters forecast issued at 0527 on 13 January reiterated that earlier forecast, and stated:

Weather Situation

A high pressure centre lies over the Tasman Sea while a strong cold front approaches from the west during Wednesday. The cold front is expected at Port Phillip and Western Port around 2100hrs.

Forecast for Wednesday 13 January until midnight

Strong Wind Warning for Wednesday for Port Phillip

Winds: Variable around 10 knots tending northerly 15 to 20 knots during the morning. Winds shifting west to northwesterly 15 to 25 knots during the afternoon ahead of a southwesterly change of 20 to 30 knots during the evening. Squalls to 45 knots possible near the change and with thunderstorms. Seas: Around 1 metre. Weather: Sunny morning. 40% chance of showers during this afternoon and evening. The chance of a thunderstorm during this afternoon and evening.

The next local waters forecast at 1041 confirmed the ‘strong cold front’ was expected at about 2100 that evening and repeated the strong wind (26 to 33 knots) warning. Significantly, both the 0527 and 1041 local waters forecasts included the possibility of squalls up to 45 knots associated with afternoon and evening thunderstorms.

Severe thunderstorms were detected in western Victoria that afternoon. As the storms moved east, severe thunderstorm warnings for damaging winds for the state were issued from 1436 onwards. Each warning included a map highlighting the warning area. The 1508 warning stated that a detailed severe thunderstorm warning for the Melbourne area would be issued should thunderstorms develop there. At 1603, a warning indicated that Melbourne may be affected, including the possibility of damaging winds (defined by BoM as exceeding 49 knots or 90 km/h).

The local waters forecast at 1640 retained information about the cold front and squalls associated with thunderstorms. At 1714, a severe thunderstorm warning was issued for the Melbourne area, which indicated that two thunderstorm cells with damaging winds located southwest of Melbourne were moving southeast (Figure 9). The next warning was due to be issued an hour later, at 1815.

Figure 9: Maps issued with the 1714 and 1737 severe thunderstorm warnings

Source: Bureau of Meteorology, with annotations by ATSB

However, at 1737, a further severe thunderstorm warning was issued after thunderstorms were detected west of Melbourne. This band of thunderstorms with winds up to 54 knots (100 km/h) was moving east toward Melbourne and forecast to affect the city by 1805. The thunderstorm passed across Station Pier at 1753, bringing with it a sudden increase in wind speed. By 1830, the storm had passed and, a couple of hours later, the thunderstorm warnings were cancelled.

Therefore, the weather experienced at Station Pier when Spirit of Tasmania II broke away on 13 January had been generally forecast, well in advance, in local waters forecasts. However, the thunderstorm that actually passed over Station Pier at 1753 was not specifically predicted until 1737 (that is, 15 minutes before the breakaway) shortly after the band of storms was detected.^[18]

Ship’s preparedness

Spirit of Tasmania II’s master had monitored successive Port Phillip local weather forecasts for the period covering the ship’s stay at Station Pier. He was aware of the strong wind warning and the ‘strong cold front’ expected in Port Phillip at 2100 on 13 January. As a precaution, he required the engine room and machinery to be at ‘short notice’^[19] from 1600, well before the cold front’s arrival.

Once the ship berthed, its bridge was not manned and weather forecasts and warnings available via VHF radio and other equipment were not continuously monitored. The master’s cabin had internet access from where he could access the BoM website. However, he was sleeping between 1330 and 1630 and remained unaware of the thunderstorm warnings issued since 1436. After he awoke, he checked the local waters forecast and found it unchanged.

At about 1700, while on the bridge, he saw that the wind and weather were also as he expected. There was no internet access on the bridge so he could not check the BoM website and remained unaware of the severe thunderstorm warning issued at 1714. After returning to his cabin at 1745, he checked the BoM website at about 1750 and saw the severe thunderstorm warning issued at 1737. By then, it was too late for the propulsion to be readied as the thunderstorm struck a couple of minutes later at 1753.

The master had use of the ship’s thrusters and main engines about 5 minutes after it broke away. He was able to use the ship’s propulsion to partially recover from the situation. Had he been able to use its propulsion earlier when the thunderstorm struck, it is likely that he would have used it to try to prevent the breakaway.^[20]

While the local waters forecasts predicted thunderstorms in the afternoon and evening, the evidence suggests that the master expected the weather to deteriorate when the cold front arrived in the evening. He had no means to automatically receive thunderstorm or squall warnings other than to continually check BoM’s website.

TT-Line expected masters to take appropriate adverse weather precautions based on their significant experience on board company ships regularly calling at the same ports. However, there were no specific trigger points for taking any particular precaution and reliance was on an individual master’s discretion and decision-making. On this occasion, the master did not become aware of the thunderstorms which developed that afternoon and precautions such as manning the bridge, monitoring the moorings or engaging tugs were therefore not taken.

The wind monitor and alarm outside the master’s cabin was of little use in providing advance warning for the thunderstorm. The alarm was set to activate (audible alarm) when a wind speed of 18 m/s (33 knots) or more persisted for at least 10 minutes. In other words, it was set to provide a warning of a steady gale force wind. The winds experienced in the thunderstorm did not activate the alarm. When the master was going to the bridge, he saw that the wind speed indicator had registered 59 knots.

The precautions taken on board Spirit of Tasmania II on 13 January provided little defence against the sudden, storm force winds experienced during the thunderstorm. Shipboard procedures for adverse weather when alongside did not take into account all the necessary factors required to provide effective defences against significant, short-term weather events such as thunderstorms.

Port’s response

The Port of Melbourne’s vessel traffic service (VTS) provides essential and timely information to masters to assist in safe and efficient traffic movement in the port. The weather is an important part of such information and VTS provides current and forecast weather reports on request via VHF channel 12. The port also requires all ships to monitor weather conditions and obtain BoM forecasts, including weather reports issued by Coast Radio Melbourne on VHF channels 16/67.

The masters of berthed ships are also required to attend to moorings to ensure their ship is appropriately and effectively secured and notify VTS if mooring lines part. High-sided ships such as car carriers are required to have a tug standing by in certain conditions depending on the berth (for example, a car carrier at Webb Dock must have a tug standing by when there is a steady wind of 30 knots or more from the south-west to west). However, there were no other requirements for berthed ships when strong winds were expected.

At the time of the incident, VTS received BoM marine weather forecasts and warnings, and severe thunderstorm warnings via email subscription. However, on 13 January, the severe thunderstorm warnings were not received due to an incorrect BoM system configuration. The harbour master was trialling a third party weather monitoring and alert system and received the warnings. He telephoned VTS at 1622 and found it had not received the state-wide severe thunderstorm warning issued by BoM at 1603. He read out the warning and then forwarded a copy to VTS.

At 1721, a Port Phillip pilot advised VTS that there were winds of about 70 knots in Geelong.^[21] At 1726, VTS contacted the harbour tug company and asked for tugs to be readied, one of which was to attend a car carrier berthed at Webb Dock. During the following 30 minutes, VTS called a number of port users (terminals, ship agents and some ships) and warned that winds over 50 knots were approaching from the west. However, neither TT-Line nor Spirit of Tasmania II was amongst the parties that VTS notified.

The VTS procedures provided for limited assistance to be given to the masters of berthed ships in the event of a weather event. The responsibility remained with the ships’ masters to monitor and respond to the weather. As a consequence, on 13 January, VTS’s response to the sudden weather event was only partially effective in dealing with the situation in Port Phillip.

Spirit of Tasmania II’s moorings

Spirit of Tasmania II’s mooring line pattern on 13 January was effectively the same as the standard pattern for that berth (Figure 6). The only difference was that a forward headspring^[22] had not been run that day, and the forward breast line was slack at the time of the breakaway. Therefore, the ship was effectively being held alongside by three mooring lines on the bight forward and six lines aft (Figure 10).

The ship’s planned maintenance system required mooring lines to be inspected every month. The maintenance records indicated that all aft lines were in good or new condition when inspected on 2 January, a few days before the breakaway. The records indicated that regular maintenance had been carried out on the mooring winches. The design winch brake holding capacity was 69 t. No defects were recorded at the previous 3 monthly mooring equipment inspection, completed in October 2015 and, while the brakes had never been render (slip and pay out) tested, there was no requirement for such testing.

Figure 10: Spirit of Tasmania II's mooring lines as run on 13 January (lines highlighted)

Source: Google Earth, with annotations by ATSB

At the time of the breakaway, all stern lines were held on the winch brake. The winches holding both aft breast lines were set to self-tension. The self-tension setting was reported to have been between 80 and 100 per cent of the winches’ rated pull^[23] of 15 t.

The CCTV footage from 1752 shows Spirit of Tasmania II’s stern moving off the wharf and its aft mooring lines stretching due to the wind loading (Figure 11). By 1753, as the wind was peaking at about 60 knots, the ship’s stern was over 4 m off the wharf with the lines considerably stretched as the winch brakes held. Moments later, the shortest stern line parted when it could not stretch any further. As the load transferred to other stern lines, they parted in quick succession.

Figure 11: CCTV images showing the ship moving off the wharf and the first line parting

Source: TT-Line Company, with annotations by ATSB

As the ship’s stern was breaking away, the winches holding the breast lines payed out. However, as the ship’s movement gathered speed, those lines parted. Two of the three forward head lines also parted during the breakaway.

Based on the pattern of the aft mooring lines (not including the spring) their combined static load capacity was approximately 200 t, as set-up.^[24] The forces from the wind loading on Spirit of Tasmania II cannot be calculated exactly because of the buildings and structures above and below Station Pier. However, if these and other complexities are ignored, a force of approximately 190 t could have been acting on the ship when the wind speed peaked.

In theory, therefore, the aft moorings should have prevented the breakaway. The moorings did hold until the wind speed reached 60 knots. Possible reasons for the failure of the mooring lines include:

• unequal tension in mooring lines (before the sudden increase in wind speed)
• not all lines were held on winch brakes (some winches on self-tension)
• unknown mooring line defects
• sudden dynamic forces (six-fold increase in wind loading)
• dynamic loading (ship’s momentum as it rapidly moved off the wharf).

It is possible that the breakaway might have been prevented had the precautions for adverse weather been more carefully considered. For example, had the breast lines been held on winch brakes, the increased static load capacity of the aft mooring line pattern may have prevented the first stern line parting. Similarly, had the ship’s propulsion been ready for immediate use, the stern thruster (maximum 15 t transverse thrust) could have been used to counteract some wind loading to prevent the first line parting.

While the standard mooring line pattern had been successfully used for many years, the breakaway indicated that the risk could have been further reduced to be better prepared for such unusual circumstances. The number, type and strength of mooring lines, winch brake testing, use of self-tension winches, bollard location and other items to improve leads for mooring lines and line tending practices are amongst the areas where enhancements may reduce risk.

__________

18. Short lead times for severe thunderstorm warnings are not unusual due to the complexity in forecasting where specific storms will develop.
19. Shipboard procedures made reference to being prepared to start engines and/or thrusters at relatively short notice - generally considered to be 5 minutes.
20. In 2013, the main engines and thrusters were used to keep Spirit of Tasmania II alongside Station Pier in a strong westerly gale during which another ship, a high sided car carrier, in the port broke away from its berth.
21. Thirty miles south-west of Station Pier.
22. A mooring line leading in a nearly fore and aft direction, the purpose of which is to prevent the ship from moving forward along the berth.
23. Rated pull is pull that the mooring line can develop at the rated winch speed on the first layer.
24. That is, with three stern lines held on the winch brake (maximum line tension 69 t), two breast lines on self-tension (maximum line tension 15 t) and accounting for the various line lead angles to the wharf.

Findings

From the evidence available, the following findings are made with respect to the breakaway of Spirit of Tasmania II that occurred at Station Pier, Melbourne on 13 January 2016. These findings should not be read as apportioning blame or liability to any particular organisation or individual.

Safety issues, or system problems, are highlighted in bold to emphasise their importance. A safety issue is an event or condition that increases safety risk and (a) can reasonably be regarded as having the potential to adversely affect the safety of future operations, and (b) is a characteristic of an organisation or a system, rather than a characteristic of a specific individual, or characteristic of an operating environment at a specific point in time.

Contributing factors

• At 1753 on 13 January, the wind speed suddenly increased from about 25 to 60 knots during a thunderstorm resulting in a six-fold increase in the wind loading force acting on Spirit of Tasmania II.
• The exponential increase in the wind loading force pushed the ship’s stern off the wharf, stretching its aft mooring lines.
• Soon after 1753, the shortest of the three stern lines (all held on winch brakes) stretched beyond its limit and parted. As the load transferred to the remaining stern lines, they parted in quick succession.
• The two breast lines aft (held on self-tension winches) payed out before parting, allowing the stern to breakaway.
• While the weather experienced, in general, was forecast well in advance, the thunderstorm was not specifically predicted until 15 minutes before the breakaway leaving little time for the ship’s crew to respond.
• The adverse weather procedures for TT-LineCompany ships when alongside did not take into account all the necessary factors to provide effective defences against significant, short-term weather events such as thunderstorms and squalls. [Safety issue]

Other factors that increased risk

• The Port of Melbourne vessel traffic service (VTS) procedures for adverse weather were not comprehensive and, hence, its response on 13 January was only partially effective. One important consequence was that VTS’s advance warning of storm force winds did not reach all relevant parties, including Spirit of Tasmania II’s master. [Safety issue]
• While TT-Line Company’s standard mooring line patternfor ships at Station Pier had been successfully used for many years, the breakaway indicated the risk could have been further reduced to better prepare for such unusual circumstances. [Safety issue]

Safety issues and actions

The safety issues identified during this investigation are listed in the Findings and Safety issues and actions sections of this report. The Australian Transport Safety Bureau (ATSB) expects that all safety issues identified by the investigation should be addressed by the relevant organisation(s). In addressing those issues, the ATSB prefers to encourage relevant organisation(s) to proactively initiate safety action, rather than to issue formal safety recommendations or safety advisory notices.

All of the directly involved parties were provided with a draft report and invited to provide submissions. As part of that process, each organisation was asked to communicate what safety actions, if any, they had carried out or were planning to carry out in relation to each safety issue relevant to their organisation.

Descriptions of each safety issue, and any associated safety recommendations, are detailed below. Click the link to read the full safety issue description, including the issue status and any safety action/s taken. Safety issues and actions are updated on this website when safety issue owners provide further information concerning the implementation of safety action.

TT-Line Company procedures

Safety issue number: MO-2016-001-SI-01

Safety issue description: The adverse weather procedures for TT-Line Company ships when alongside did not take into account all the necessary factors to provide effective defences against significant, short-term weather events such as thunderstorms and squalls.

Melbourne vessel traffic service procedures

Safety issue number: MO-2016-001-SI-02

Safety issue description: The Victorian Ports Corporation (Melbourne) advised the ATSB that it had issued Victorian Notices to Mariners number 032-2016 advising that Melbourne vessel traffic service will broadcast Bureau of Meteorology weather warnings on VHF channel 12. All masters of ships in port waters, including at berth or anchorage, are to ensure a listening watch is maintained at all times.

A Port Information Notice (PIN number 08/2016) was also issued for passenger ships at Station Pier to ensure adequate mooring lines are used throughout the ships’ stay. Masters are reminded that the berth is exposed to strong winds and inclement weather. They are to keep a listening watch on VHF channel 12.

Mooring at Station Pier

Safety issue number: MO-2016-001-SI-03

Safety issue description: While TT-Line Company’s standard mooring line pattern for ships at Station Pier had been successfully used for many years, the breakaway indicated the risk could have been further reduced to better prepare for such unusual circumstances.

Appendices

Appendix A – Bureau of Meteorology weather service and terms

The Bureau of Meteorology (BoM) provides the maritime community with weather forecasts, warnings and observations for coastal waters areas around Australia.

Marine and local waters forecasts

Forecasts for wind speed and direction, and sea and swell heights are issued routinely every 12 hours. When a marine wind warning is in force, these forecasts are updated routinely every 6 hours. These forecasts provide information on mean wind, sea height, swell height and direction and weather conditions:

• local waters - areas such as bays, harbours and inland waters on which frequent boating activity occurs
• coastal waters – areas within 60 miles of the coast.

The following terminology is used to describe time periods in these forecasts:

• Early in the morning - expected to occur before 0600
• In the morning - expected to occur between 0700 and 1000
• Middle of the day - expected to occur between 1100 and 1300
• During early afternoon - expected to occur between 1400 and 1500
• In the afternoon - expected to occur between 1600 and 1800
• During the evening - expected to occur between 1900 and 2000
• Later in the evening - expected to occur after 2100.

All BoM marine forecasts and warnings predict wind speed as the average (or mean) speed expected over any given 10 minute period at a height of 10 m above the ground. Hence, marine forecasts provide a summary of the average wind speed expected within the forecast area, not the maximum wind gust expected.

Wind warnings are only issued when mean winds (winds speed averaged over 10 minutes) are expected to exceed 25 knots for an extended period of time across more than 10 per cent of the marine area. A wind warning is not issued for individual wind gusts, which typically last seconds.

In the absence of severe weather, such as thunderstorms or squalls, it is normal for wind speed to vary by up to 40 per cent over a 10 minute period. Hence, a statement is added to BoM marine forecasts to remind users that wind gusts at any time can be 40 per cent higher than the mean wind predicted in BoM marine forecasts and warnings. Wind gusts can be much higher than 40 per cent during severe weather, such as thunderstorms or squalls.

Mariners should refer to the weather section of the coastal or local waters forecast to determine the likelihood of thunderstorms occurring. They should also be aware that there is a risk of damaging wind gusts occurring with any thunderstorm and should actively monitor weather conditions when thunderstorms are forecast.

For operations near the shore, BoM’s severe thunderstorm warning service should also be used. These warnings provide short-term advanced notice of thunderstorms that are likely to be accompanied with wind gusts in excess of 48 knots, as well as other hazardous conditions that can accompany thunderstorms.

Recipients are further cautioned that maximum wave heights may be up to twice the height of those forecast (average). More information is available from the BoM website.

Marine weather warnings

Marine weather warnings are issued whenever strong winds, gales, storm force or hurricane force winds are expected. The following warnings are provided:

• coastal waters wind warnings
• ocean wind warnings – issued to ships at sea whenever gale, storm or hurricane force winds are expected
• severe weather warnings – provided for potentially hazardous or dangerous weather that is not directly related to severe thunderstorms, tropical cyclones or bushfires.

Gust speed can be 40 per cent greater than the predicted wind speed.

Marine wind warnings aim to provide a 24-hour lead-time and are normally reviewed every 6 hours and issued every 12 hours.

Wind speed warnings

These warnings are issued whenever strong winds, gale, storm or hurricane force winds are expected. They provide around 42 to 24 hours’ notice and are updated every 6 hours. The wind warning statement is included in all the coastal waters and local waters forecasts affected by the warning. A state-wide marine wind warning summary is also available and lists all the coastal waters and local waters affected by warnings for that day and the following day (listed on the BoM’s National warnings summary webpage).

These warnings are based on expected 10 minute mean winds (not maximum wind gusts) and are only issued if mean winds are expected to exceed thresholds for extended periods. The following 10 minute mean thresholds are used:

• strong wind warning: 26 to 33 knots, force 6 to 7^[25]
• gale warning: 34 to 47 knots, force 8 to 9
• storm force wind warning: 48 to 63 knots, force 10 to 11
• hurricane force wind warning: 64 knots or more, force 12.

Wind direction is given using the eight compass points for forecasts and 16 points for observations and is the direction the wind is coming from.

Severe thunderstorm and severe weather warnings

Severe thunderstorm warnings provide short-term advance warning of the likelihood of severe thunderstorms impacting on the region and are updated every three hours. A severe thunderstorm can produce any of the following:

• a tornado
• large hail (2 cm in diameter or larger)
• damaging wind gusts (generally wind gusts exceeding 48 knots )
• heavy rainfall which may cause flash flooding.

Severe weather warnings are issued for the following conditions:

• sustained winds of gale force (34 knots or more) wind gusts of 48 knots or more
• very heavy rain abnormally high tides
• unusually large surf waves expected to cause dangerous conditions on the coast.

The BoM’s forecasters determine which warnings to issue to best inform the public about the hazards – for example, a severe weather warning may not be issued if a severe thunderstorm warning has already been issued.

While both the severe thunderstorm and severe weather warnings are land-based products, people undertaking marine operations near the shore should also consider these warnings.

Terms used

Wind speed is the average speed of the wind over a 10-minute period at a height of 10 m above the surface level.

Gusts are increases in wind speed lasting for just a few seconds. Wind gusts are typically 40 per cent stronger than the average wind speeds provided in marine forecasts. However, thunderstorms and squalls may produce much higher gusts.

A squall is an abrupt and large increase in wind speed that usually only lasts for minutes then diminishes rather suddenly. The gusts in a squall may exceed 40 or 50 knots.

More information is available from the BoM website.

Appendix B – Bureau of Meteorology weather monitoring tools

The Bureau of Meteorology (BoM) provides a great deal of information and weather monitoring tools to users via its website www.bom.gov.au. In addition to its official warnings and marine forecasts, the BoM provides the following weather monitoring and forecast tools.

Australian weather watch radar

The BoM provides a system of dedicated and part-time weather watch radars with images available online.^[26] The images are updated about every 10 minutes for the dedicated system. The primary image display is of rainfall rates.

There are fifteen levels of rainfall intensity shown on the images - each level provides an approximate indication of the rainfall rate in millimetres per hour. Rain radar is not an indicator or predictor of the wind speed although there is some correlation between the severity or concentration of the displayed rain pattern and associated weather events (such as localised storms) and wind strength.

Thunderstorm precipitation cells can appear as isolated cells or in clusters or lines. Fast moving cells, rapidly growing cells, a bow in the direction of the movement of a line of cells and/or a long-lived cell moving in a markedly different direction to others may indicate the potential for severe weather (large hail, damaging winds and/or very heavy rain).

Where available, the individual weather radar is able to display Doppler wind data. Unlike the rain radar images, the Doppler wind data can be difficult to understand and interpret. Due to the complexities of interpretation, the BoM warn that care should be taken when using this data.

The information displayed on radar images is always historical being at least 10 minutes old and is based on average rather than instantaneous readings.

MetEye™

MetEye™ is an online^[27] weather-mapping tool which displays forecasts, in three-hourly blocks, for weather features including wind speed and direction. MetEye™ allows animation of a range of official BoM forecast grids including rainfall, temperature and wind. These forecasts are updated twice daily. The system also allows information from other sources such as latest weather information including rain radar and wind speed and direction to be overlayed.

The wind forecast maps show the averaged 10 minute wind speed and direction for the time selected, based on a 10 m standard height. As wind speeds vary with gusts and lulls during a 10 minute period so the wind gusts experienced may be 40 percent stronger than the average speeds presented on the map.

MetEye™ is not a suitable real-time weather tracking or monitoring tool, especially for short-term weather events such as squalls and thunderstorms, as it is based upon forecasts from 10 minute average readings taken as much as 3 hours before the current time. Data refresh times vary and the most recent information is at least 6 minutes old. For this reason, care must be taken when using the tool for weather-based decisions.

Marine wind forecast

The BoM also provides computer generated marine wind forecast maps. The maps show average wind speeds and should be used in conjunction with official BoM marine weather forecasts as additional information and forecaster expertise are used to generate the official forecasts.

Accessing marine forecast and warning services

All BoM forecasts and warnings are available on the BoM website. In addition, there are a number of communication methods mariners can use to check BoM marine services, forecasts, warnings and observations:

• Email subscription service – interested parties can subscribe to and receive a range of BoM services as they are released, including forecasts and warnings.
• MarineLite (marine weather services (lite): includes high seas, coastal and local waters forecasts and warnings in text-only format, making them faster, more affordable and more accessible for slow data links.
• VHF voice radio: inshore, broadcasts at scheduled times, provided by local marine organisations.
• HF voice radio: off-shore, broadcast continuously 24/7, provided by BoM.
• Inmarsat: global satellite communications for high seas warnings and forecasts, some coastal forecasts, provided by BoM for Australian high seas and coastal areas.
• Telephone weather services: pre-recorded coastal and local waters forecasts and warnings for each State/Territory.
• Marine weather knowledge centre – this web-based service provides a one-stop webpage for marine weather education information. The site includes a range of educational material to support the improved understanding of, and accessibility to, the existing information on BoM's Marine & Oceans webpage.
• Mobile phone application, BoM Weather – users can view weather information (forecasts, warnings, rain radar, wind) for any location.

Note that severe thunderstorm warnings are not provided on HF radio or Inmarsat.

__________

25. The Beaufort scale of wind force, developed in 1805 by Admiral Sir Francis Beaufort, enables sailors to estimate wind speeds through visual observations of sea states.
26. www.bom.gov.au/australia/radar
27. www.bom.gov.au/australia/meteye

Sources and submissions

Sources of information

On 14 January 2016, investigators from the Australian Transport Safety Bureau (ATSB) attended Spirit of Tasmania II while the ship was in Melbourne, Victoria. The master and directly involved crewmembers were interviewed and each provided their account of the occurrence. Photographs of the ship and copies of available, relevant documents were obtained.

References

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Australian Maritime Safety Authority (AMSA) 2016, Maritime Safety Awareness Bulletin, Issue 2 – Thinking – mooring safety, AMSA, Canberra. Available at www.amsa.gov.au

Babicz, J 2015, WartsilaEncyclopedia of Ship Technology, 2nd edn, Wartsila Corporation, Helsinki. Available at www.shippingencyclopedia.com

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Clark, IC 2009, Mooring and Anchoring Ships, Volume 1: Principles and Practice, The Nautical Institute, London.

Haddara, M & Soares, CG 1999, ‘Wind loads on marine structures’, Marine Structures, 12(3), pp.199-209.

International Association of Classification Societies (IACS) 2005, Recommendation No.10 Equipment, IACS. Available at www.iacs.org.uk

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International Maritime Organisation (IMO) 2005, MSC Circular 1175: Guidance on shipboard towing and mooring equipment, IMO, London.

Oil Companies International Marine Forum (OCIMF) 1989, Effective Mooring, OCIMF, Bermuda.

Oil Companies International Marine Forum (OCIMF) 2008, Mooring Equipment Guidelines, 3rdedn, OCIMF, Bermuda.

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Port of Melbourne Corporation (PoMC) 2015, Port Information Guide, PoMC, Melbourne. Available at www.vicports.vic.gov.au

Port of Melbourne Corporation (PoMC) 2015, Harbour Master’s Directions, PoMC, Melbourne. Available at www.vicports.vic.gov.au

Steamship Mutual 2015 Risk Alert – Mooring winch brake holding capacity, Steamship Mutual, London. Available at www.steamshipmutual.com/loss-prevention

Thoresen, CA 2014, Port Designer’s Handbook, 3rdedn, Institute of Civil Engineers, London.

Turk, A & Prpic-Orsic, J 2009, ‘Estimation of Extreme Wind Loads on Marine Objects’, BrodoGradnja, 60(2), pp. 147-156.

UK P&I Club 2002, Technical bulletin Number 1, 2002 Mooring Practices, UK P&I Club, London.

Witherby Seamanship International 2007, Tanker Jetty Safety, Witherbys, London. Available through www.witherbyseamanship.com

Submissions

Under Part 4, Division 2 (Investigation Reports), Section 26 of the Transport Safety Investigation Act 2003 (the Act), the Australian Transport Safety Bureau (ATSB) may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. Section 26 (1) (a) of the Act allows a person receiving a draft report to make submissions to the ATSB about the draft report.

A draft of this report was provided to TT-Line Company, the master and chief mate of Spirit of Tasmania II, the Australian Maritime Safety Authority, Victorian Ports Corporation (Melbourne), American Bureau of Shipping and the Bureau of Meteorology.

Submissions were received from TT-Line Company, the master and chief mate of Spirit of Tasmania II, the Australian Maritime Safety Authority, Victorian Ports Corporation (Melbourne), American Bureau of Shipping and the Bureau of Meteorology. The submissions were reviewed and where considered appropriate, the text of the report was amended accordingly.

Purpose of safety investigations & publishing information

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2017 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

What happened

On the afternoon of 10 October 2014, the pilot of an amateur-built One Design DR-107 aircraft, registered VH-EGT, was performing low-level aerobatic manoeuvres. The manoeuvres were being performed to the east of Goolwa Airport, South Australia.

Witnesses described the aircraft performing a series of similar manoeuvres. Each involved a vertical climb and tumbling manoeuvre followed by a vertical dive and a low altitude recovery.

Witnesses reported that, during recovery from the last vertical dive, the aircraft collided with terrain. The aircraft was destroyed by the impact and the pilot was fatally injured.

What the ATSB found

The ATSB found no evidence of pilot incapacitation or a mechanical fault with the aircraft that could have contributed to the accident. There was insufficient evidence to determine why the recovery was not accomplished above the pilot’s minimum authorised aerobatics height.

The Civil Aviation Safety Authority (CASA) recommends that pilots performing low-level aerobatics undertake regular peer reviews due to the high level of skill and fine safety margins involved. The ATSB found no evidence of the pilot undertaking a peer review of their aerobatic performance in the 15 months prior to the accident.

Finally, the ATSB identified a safety issue that CASA does not require builders of amateur-built experimental aircraft to produce a flight manual, or equivalent, for their aircraft following flight testing. Without a flight manual, the builder, subsequent owners and other pilots do not have reference to the operational and performance data necessary to safely operate the aircraft.

What’s been done as a result

In response to the identified safety issue, the ATSB has issued a safety recommendation to CASA to take action to require builders of amateur-built experimental aircraft to produce a flight manual, or equivalent, for their aircraft following flight testing.

Safety message

This accident highlights the risks inherent in performing low-level aerobatics. Applying the recommendations in CASA civil aviation advisory publication CAAP 155-1(0) Aerobatics will reduce these risks. Specifically, pilots are encouraged to always maintain minimum approved heights above the ground when performing aerobatics and to engage in regular peer reviews.

Owners of amateur built experimental aircraft are also encouraged to ensure a comprehensive and accurate flight manual, or equivalent, is available for reference by themselves, subsequent owners and other pilots who may fly the aircraft.

Amateur-built One Design DR-107 aircraft, registered VH-EGT

The occurrence

On the afternoon of 10 October 2014, the pilot of an amateur-built One Design DR-107 (DR-107) aircraft, registered VH-EGT (EGT), was performing low-level aerobatic manoeuvres to the east of Goolwa Airport, South Australia. The aerobatics were observed by a number of witnesses and described as consisting of a series of repeated manoeuvres. Specifically, the aircraft was seen to conduct a number of vertical climbs and tumbling manoeuvres, followed by a vertical dive and a low altitude recovery.

Witnesses observed that as the aircraft started to recover from a vertical dive it collided with terrain. The two witnesses furthest from the aircraft reported that the aircraft was rolling or spiralling while in the final vertical dive. By contrast, the two closest witnesses reported the aircraft was not rolling or spiralling during the final vertical dive.

The collision occurred at about 1430 Central Daylight-saving Time^[1] in a paddock to the east of Goolwa Airport (Figure 1). Emergency services received a telephone call from a witness to the accident at 1431. Police, fire and ambulance personnel arrived at the accident site by 1443. The aircraft was destroyed by the impact and the pilot was fatally injured.

Figure 1: Goolwa Airport showing the location of the aircraft wreckage and witness locations. The runway is oriented basically north/south

Source: Google earth, modified by the ATSB

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1. Central Daylight-saving Time (CDT) was Coordinated Universal Time (UTC) + 10.5 hours.

Context

Pilot information

The pilot held a Private Pilot (Aeroplane) Licence, issued in March 1983, with the appropriate aircraft endorsements to operate a DR-107-type aircraft. The pilot also held a valid and unrestricted Class 2 Aviation Medical Certificate, issued by the Civil Aviation Safety Authority (CASA).

The pilot’s last recorded biennial aeroplane flight review was on 4 September 2013. Entries in the pilot’s logbook recorded a total flying experience of 993 hours to 20 September 2013. There were no further entries in the pilot’s logbook after this date. The pilot had logged a total of 201.8 hours in EGT to 20 September 2013. From that date, entries in EGT’s maintenance release indicated the pilot flew the aircraft for a further 16.8 hours. It could not be determined if the pilot flew any aircraft other than EGT after 20 September 2013.

In November 1990 the pilot was assessed as competent, by a CASA Approved Testing Officer, to recover from spins in a Cessna 152-type aircraft and to perform basic aerobatic manoeuvres. The manoeuvres included loops, aileron rolls, slow rolls, barrel rolls and stall turns.

In order for CASA to grant a low-level aerobatics approval, pilots were required to demonstrate proficiency at progressively lower levels. The pilot was granted progressively lower low-level aerobatics approvals as follows:

• in August 2009, the pilot was found competent to recover from inverted spins and to perform low-level aerobatics down to 500 ft above ground level^[2]
• in August 2011, the pilot was found competent to perform low-level aerobatics down to 330 ft and to perform non-aerobatic manoeuvres down to 100 ft.

In August 2013 CASA renewed the pilot’s low-level aerobatics approval for a further 2 years. The pilot’s continued competence to perform low-level aerobatics was not re-assessed prior to this renewal.

The pilot exceeded the recommended minimum recent experience for low-level aerobatics contained in Civil Aviation Advisory Publication (CAAP) 155-1(0) Aerobatics.

Aircraft information

General

The aircraft was a single seat, low wing, fixed gear, amateur-built^[3] aircraft designed for competition aerobatics (Figure 2). Entries in the aircraft’s logbook indicated that the pilot commenced construction of the aircraft as an amateur builder in October 2003. The aircraft was completed in March 2008. A CASA authorised person issued a special certificate of airworthiness in the experimental category on 13 March 2008.

Figure 2: Amateur-built One Design DR-107 aircraft, registered VH-EGT

Source: FlightAware

The last entry in the aircraft’s maintenance records was the removal, by the pilot,^[4] of the propeller and engine in September 2013. The pilot removed the engine and propeller from the aircraft for overhaul following a propeller overspeed. There was no record of the engine and propeller overhaul or subsequent installation in the aircraft. There was also no record of the last annual inspection performed on the aircraft.

On 14 January 2014, the pilot issued a maintenance release that was valid for 12 months. This allowed the aircraft to be operated privately under the day visual flight rules.^[5] The aircraft flew for 16.8 hours between 14 January 2014 and the accident. No defects or unserviceable equipment endorsements were recorded on the maintenance release.

Aircraft weight and balance

The pilot, as builder of the aircraft, determined the aircraft’s empty weight and balance limits and produced a weighing summary document in March 2008. The empty weight was recorded to be 475 kg. The ATSB found no record of a maximum take-off weight (MTOW) in the aircraft’s records or the CASA aircraft file. No flight manual or placards relating to the aircraft’s weight and balance were found.

The kit supplier of the plans and building materials for the aircraft specified an empty weight of 322 kg and a MTOW of 517 kg. The aircraft’s weighing summary contained an aerobatic weight of 610 kg, which is 93 kg above the kit supplier’s listed MTOW. CASA allowed builders of amateur-built experimental aircraft to nominate their own MTOW. However, builders are required to demonstrate that their aircraft are safe to fly at their nominated MTOW during flight testing. Logbook entries indicated that the aircraft was test flown at approximately 610 kg on 1 and 2 June 2008.

The aircraft designer determined that the aircraft was capable of withstanding a flight load factor of plus or minus 10 g^[6] at a weight of 454 kg. Operations at weights above this required a corresponding decrease in the maximum flight load factor. This included a corresponding reduction in the aircraft’s maximum manoeuvring speed (VA).^[7] The ATSB determined that the manoeuvring speed on the aircraft’s airspeed indicator was marked appropriately for a 610 kg aerobatic weight. The VA marking on the airspeed indicator, in the absence of a flight manual, indicated the application of a reduced flight load factor limit.

The ATSB surveyed DR-107 owners on the Australian civil aircraft register to place the aircraft’s MTOW in context with other aircraft of the same type. Reported empty weights varied from 408 kg to 493 kg. MTOWs varied from 550 kg to 669 kg. One responder stated that their aircraft did not have a MTOW.

Flight manuals

The ATSB found no evidence that a flight manual or equivalent placarding was produced for the aircraft. A flight manual documents emergency procedures, systems information, operational and performance data necessary to safely operate an aircraft. For certified aircraft,^[8] a flight manual is produced by the aircraft manufacturer for use by any pilot who flies the aircraft. For an amateur-built experimental aircraft, the builder of the aircraft is considered the manufacturer.

As each amateur-built aircraft is unique, CASA requires the builder to test their aircraft following construction. The purpose of flight testing is to determine that the aircraft is safe to fly and to determine the aircraft’s flight limits and performance characteristics. CASA recommends, but does not require, builders of amateur-built experimental aircraft to produce a flight manual for their aircraft following flight testing.

The ATSB’s survey of DR-107 owners indicated that half of the responders did not have a flight manual. The owners without a flight manual were not the builders of their aircraft, having purchased their aircraft from the builder or a subsequent owner.

Meteorological information

The Bureau of Meteorology did not provide observations or forecasts for Goolwa Airport. The area forecast^[9] covering Goolwa Airport indicated that a trough would pass over the airport from the south-west at around the time of the accident. Low altitude winds were forecast to change from the north-west to the south-west as the trough passed.

Weather observations from nearby Victor Harbour and Hindmarsh Island indicated that the trough passed Goolwa at least 2 hours before the accident.

Witnesses at Goolwa Airport reported that the weather was fine and sunny with good visibility at the time of the accident. Witnesses also reported a ‘strong wind’ coming from the south-west. Due to low terrain to the south-west of Goolwa Airport, the presence of mechanical turbulence was considered unlikely.

Wreckage and impact information

On-site examination

The accident site was in a flat, recently harvested paddock adjacent to Goolwa Airport. The aircraft collided with terrain approximately 400 m east of the northern end of runway 01/19.^[10] The wreckage trail was approximately 45 m long on a bearing of 115°. The length of the wreckage trail, combined with the initial ground impact mark and damage to the aircraft, indicated an impact at relatively high vertical and horizontal speed. Ground impact marks and aircraft damage further indicated that the aircraft collided with terrain in a wings level, slightly nose down pitch attitude (Figure 3).

Figure 3: Initial ground scar

Fuel soaked soil was identified under the wreckage, indicating that the aircraft’s fuel tank contained fuel prior to its disruption during the impact sequence. No evidence was found of any fault with the aircraft that could have contributed to the accident.

Propeller ground impact marks, blade dispersion and damage was consistent with the engine operating under power at the time of the accident. Witness reports of engine noise were consistent with the engine operating normally up to the collision with terrain. There was no evidence of an in-flight fire or break-up.

The aircraft was not fitted with a fixed emergency locator transmitter, nor was it required to be by regulation.

Medical and pathological information

The forensic pathologist who conducted the post-mortem examination concluded that the pilot succumbed to injuries sustained during the impact sequence. No abnormalities were identified that could have led to pilot incapacitation.

Toxicology results did not identify any substances that could have impaired the pilot’s performance.

Operational information

Aerobatic manoeuvres

Witnesses reported that the pilot was performing low-level aerobatic manoeuvres on the day of the accident, including vertical dives. Vertical dives meet the definition of an aerobatic manoeuvre contained in CAAP 155-1(0). There was insufficient evidence to determine the height at which the pilot was recovering from the vertical dives.

The ATSB was unable to determine the reason why the pilot was performing low-level aerobatics. However, the pilot had previously performed air show aerobatic routines and may have been practicing for an upcoming performance.

An experienced aerobatic pilot pointed to the possibility that the aircraft was in a spin,^[11] which may have become an inverted spin during the final descent. While there was insufficient evidence to confirm that proposition, such a development would have required additional time, and therefore height, to recover the aircraft to level flight.

The ATSB obtained video evidence of the pilot performing aerobatic manoeuvres at Goolwa Airport significantly below 330 ft 1 week prior to the accident. This was below the height that the pilot was permitted to engage in aerobatic flight.

Peer reviews

Due to the ‘high level of skill and fine safety margins’ in low-level aerobatics, CAAP 155-1(0) part 7.28.1 strongly suggested pilots undertake regular peer reviews of their aerobatic performance. In this respect, Part 7.28.2 of the CAAP stated:

The peer review process is intended to provide an independent assessment by a similarly qualified person or persons on the way the pilot conducts the activity and to identify any incorrect techniques or practices that the pilot may have developed over time. It is not intended to be a flight test for the renewal of the permission, but an opportunity for constructive discussion with other practitioners with a view to enhancing the safety of a pilot’s performance.

CAAP 155-1(0) recommended a maximum of 15 months between reviews. The ATSB was unable to find any evidence of the pilot undertaking a peer review of their aerobatic performance in the 15 months before the accident.

Tests and research

Research by the ATSB identified that the accident rate of experimental amateur-built aircraft was significantly higher than for similar factory-built aircraft. Specifically, ATSB research investigation AR-2007-043(2) Amateur-built aircraft Part 2: Analysis of accidents involving VH-registered non-factory-built-aeroplanes 1988-2010 available at ATSB wesite identified that:

The fatal/serious injury accident rate across the period of the study was significantly higher for amateur-built aircraft (average 1.27 per 10,000 hours) than it was for similar factory-built aircraft (average 0.22). The fatal and serious injury accident rate was more than 5.5 times higher for amateur-built aircraft compared to factory-built during private operations.

Similar to the total accident rate, the fatal/serious injury accident has reduced from 1988-1999 to 1999-2010, but the reduction has been significantly greater for amateur-built aircraft. In the second half of the period of study from 1999-2010, the fatal/serious injury accident rate was more than 3.5 times higher for amateur-built aircraft.

Those results were consistent with the findings of the United States National Transportation Safety Board (NTSB) safety study NTSB/SS-12/01 The Safety of Experimental Amateur-Built Aircraft available at NTSB website. The abstract of that study noted that:

Experimental amateur-built (E-AB) aircraft represent nearly 10 percent of the U.S. general aviation fleet, but these aircraft accounted for approximately 15 percent of the total—and 21 percent of the fatal—U.S. general aviation accidents in 2011…

The NTSB study also stated that:

Areas identified for safety improvement include expanding the documentation requirements for initial aircraft airworthiness certification, verifying the completion of Phase I flight testing, improving pilots’ access to transition training and supporting efforts to facilitate that training, encouraging the use of recorded data during flight testing, ensuring that buyers of used E-AB aircraft receive necessary performance documentation, and improving aircraft identification in registry records.

As a result of their safety study, the NTSB made a number of recommendations to the United States Federal Aviation Administration (FAA) that were aimed at improving the safety of amateur-built aircraft. These included recommendations that the FAA:

Revise 14 Code of Federal Regulations 21.193, Federal Aviation Administration Order 8130.2G, and related guidance or regulations, as necessary, to require applicants for an airworthiness certificate for experimental, operating amateur-built aircraft to submit for Federal Aviation Administration acceptance a flight test plan that will (1) ensure the aircraft has been adequately tested and has been determined to be safe to fly within the aircraft’s flight envelope and (2) produce flight test data to develop an accurate and complete aircraft flight manual and to establish emergency procedures and make a copy of this flight test plan part of the aircraft’s certification file. (A-12-29)

…

Revise Federal Aviation Administration Order 8130.2G, and related guidance or regulations, as necessary, to require the review and acceptance of the completed test plan documents and aircraft flight manual (or its equivalent) that documents the aircraft’s performance data and operating envelope, and that establishes emergency procedures, prior to the issuance of Phase II operating limitations. (A-12-32)

The FAA responded to these NTSB recommendations on 24 September 2012 and advised that they were ‘creating a cross organizational Amateur-Built Safety Team to review the current guidance and policy for amateur-built certification and operation.’ At the time of writing, no further safety action had been reported to the NTSB.

Related occurrences

A review of the ATSB occurrence database identified three potentially similar accidents that occurred during aerobatic manoeuvres. Of these, two involved amateur-built aircraft. One of the occurrences was preceded by a loss of engine power during take-off. There was insufficient information available on the circumstances of the other two occurrences to determine if they were substantially similar to this accident.

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2. Unless indicated otherwise, aerobatic heights are above ground level.
3. An amateur-built aircraft is an aircraft, the major portion of which has been fabricated and assembled by a person or persons who undertook the construction project solely for their own education or recreation.
4. Amateur builders are permitted to maintain their aircraft and to issue maintenance releases subject to the conditions in CASA Instrument number CASA 33/13.
5. Visual flight rules (VFR) are a set of regulations that allow a pilot to only operate an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going.
6. G Load is the nominal value for acceleration. In flight, g load values represent the combined effects of flight manoeuvring loads and turbulence. This can be a positive or negative value.
7. Manoeuvring speed (VA) is the speed above which full deflection of the flight control(s) will exceed aircraft structural limitations.
8. A certified aircraft has a Certificate of Airworthiness issued by CASA stating that the aircraft type meets all requirements on grounds of safety.
9. Australia is subdivided into a number of aviation forecast areas.
10. Runways are named by a number representing the magnetic heading of the runway.
11. A spin is a sustained spiral descent with the wings stalled; in most cases a stable autorotation.

Safety analysis

Introduction

While performing aerobatic manoeuvres the pilot did not fully recover the aircraft from a vertical dive before colliding with terrain. The ATSB did not find any evidence of pilot incapacitation or a fault with the aircraft that could have contributed to the accident. The weather conditions were also considered unlikely to have influenced the development of the accident. Additionally, the pilot was qualified to perform low-level aerobatics down to 330 ft and the aircraft type was appropriate for the aerobatic manoeuvres being performed that day.

This analysis will consider the possible reasons why aerobatic flight was continued below 330 ft. In addition, the safety benefit of aerobatic peer reviews and provision of aircraft flight manuals for amateur built experimental aircraft will be discussed.

The occurrence

The accident site ground impact marks and aircraft damage indicated that the aircraft was in a slightly nose low, wings level attitude at impact. Additionally, the ATSB determined that the aircraft collided with terrain with a high vertical and horizontal speed. This evidence is consistent with witness reports indicating that the aircraft appeared to be pulling out of a dive when it collided with terrain.

There was insufficient evidence to determine why the recovery was not accomplished above the pilot’s minimum aerobatics height of 330 ft. It is possible that the pilot either intentionally or inadvertently delayed the recovery of the aircraft during the vertical dive.

Misjudgement of the height that recovery was initiated

The ATSB was unable to determine the intended lowest height of the aerobatics on the day of the accident. However, evidence was provided to the ATSB that the pilot performed aerobatic manoeuvres significantly below 330 ft 1 week prior to the accident.

It is possible that the pilot was completing the aerobatic manoeuvres below 330 ft on the day of the accident. If this occurred, a misjudgement of the recovery initiation height may have resulted in insufficient remaining height above terrain for the pilot to recover the aircraft from the vertical dive before impacting terrain.

Inadvertent late initiation of the recovery

Raising the aircraft’s pitch attitude from vertical nose-down to close to horizontal while maintaining the wings level required active inputs by the pilot and flight control authority. Consequently, pilot incapacitation or a fault with the aircraft’s flight controls were considered unlikely. Momentary incapacitation of the pilot or an intermittent aircraft fault that distracted the pilot and delayed initiation of the recovery; however, could not be ruled out.

Witness descriptions of the aircraft rolling or spiralling were consistent with the aircraft being in a spin during the final descent. However, the two closest witnesses described the aircraft descending vertically without spinning. Additionally, observations of the attempted recovery and accident site ground impact marks indicated that the aircraft was not in a spin when it collided with terrain. If the aircraft had inadvertently entered an inverted spin at some stage during the vertical dive, additional height would have been required to recover the aircraft to level flight. In that case, the possibility that there was insufficient height available to fully recover the aircraft could not be ruled out.

Aerobatics peer review

The ATSB found no evidence of the pilot undertaking a peer review of their aerobatic performance in the 15 months prior to the accident. A peer review, as suggested by Civil Aviation Advisory Publication 155-1(0) Aerobatics has the potential to help a pilot maintain safety margins in low-level aerobatic routines, and may have assisted the pilot avoid inadvertently breaching their minimum approved aerobatics height. However, there was insufficient evidence to determine if the non-completion of the peer review influenced the development of the accident.

Aircraft flight manual

The Civil Aviation Safety Authority did not require amateur-built experimental aircraft to have a flight manual or equivalent placards. The ATSB found no evidence that a flight manual or equivalent placarding was produced for the aircraft following flight testing. The lack of a flight manual was unlikely to have influenced this accident due to the pilot's familiarity with the aircraft. This familiarity was a result of their experience building, test flying and operating the aircraft.

However, as evidenced by the recommendations made to the United States Federal Aviation Administration by the National Transportation Safety Board, not having a flight manual increases the risk associated with amateur-built experimental aircraft operations. Without a flight manual the builder, other pilots and especially subsequent owners do not have reference to operational and performance data necessary to safely operate the aircraft. Given that accidents involving amateur-built aircraft occur at a significantly higher rate than comparable factory-built aircraft, a requirement to document important operational information would be a valuable safety enhancement.

Findings

From the evidence available, the following findings are made with respect to the collision with terrain involving One Design DR-107 aircraft, registered VH-EGT, which occurred near Goolwa Airport, South Australia on 10 October 2014. These findings should not be read as apportioning blame or liability to any particular organisation or individual.

Safety issues, or system problems, are highlighted in bold to emphasise their importance. A safety issue is an event or condition that increases safety risk and (a) can reasonably be regarded as having the potential to adversely affect the safety of future operations, and (b) is a characteristic of an organisation or a system, rather than a characteristic of a specific individual, or characteristic of an operating environment at a specific point in time.

Contributing factors

• The aircraft collided with terrain while the pilot was attempting to recover from an aerobatic manoeuvre at low level.

Other factors that increased risk

• Although suggested by Civil Aviation Advisory Publication 155-1(0) Aerobatics, the pilot probably did not undertake a peer review of their aerobatic performance in the preceding 15 months to the accident.
• The Civil Aviation Safety Authority did not require builders of amateur-built experimental aircraft to produce a flight manual, or equivalent, for their aircraft following flight testing. Without a flight manual the builder, other pilots and subsequent owners do not have reference to operational and performance data necessary to safely operate the aircraft. [Safety issue]

Sources and submissions

Sources of information

The sources of information during the investigation included:

• an experienced aerobatic pilot
• the Bureau of Meteorology
• the Civil Aviation Safety Authority (CASA)
• the South Australian Police and Forensic Science SA
• the One Design DR-107 designer
• a number of other One Design DR-107 aircraft owners.

Submissions

Under Part 4, Division 2 (Investigation Reports), Section 26 of the Transport Safety Investigation Act 2003 (the Act), the ATSB may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. Section 26 (1) (a) of the Act allows a person receiving a draft report to make submissions to the ATSB about the draft report.

A draft of this report was provided to the experienced aerobatic pilot, the Sport Aircraft Association of Australia and CASA.

Submissions were received from the experienced aerobatic pilot, the Sport Aircraft Association Australia and CASA. The submissions were reviewed and where considered appropriate, the text of the report was amended accordingly.

Purpose of safety investigations & publishing information

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

What happened

On 28 March 2016, at about 1306 Eastern Daylight-saving Time (EDT), a Schemp-Hirth Janus glider, registered VH-GWQ (GWQ) launched from Porepunkah Airfield, Victoria, for a pleasure flight. On board were two pilots. The pilot seated in the rear seat was the pilot in command for the flight. The glider tracked over Simmons Gap, to a ridge about 3 km north-west of Mount Beauty Airport (Figure 1). The pilots could hear and see other gliders being towed onto the ridge. They joined a thermal^[1] and climbed in tight orbits (‘thermalling’) in a clockwise direction.

Figure 1: Relative tracks of gliders VH-GWQ and VH-CQP and positions at 1355:02

Source: Gliding Federation of Australia

At about 1335, the pilot of a Rolladen-Schneider LS3-A glider, registered VH-CQP (CQP), launched from Mount Beauty Airport, Victoria, for a pleasure flight. At about 1355, the glider was 3 to 4 km north-west of the airfield and descending through about 4,000 ft, when the pilot heard an alarm sounding, but did not identify it as issuing from the FLARM collision avoidance system (see FLARM below) fitted to the glider. The glider was tracking to the north, and the pilot reported that they had been keeping a lookout for other gliders but were not aware of any in the vicinity at the time.

The pilot tried to identify the source of the alarm inside the cockpit, which diverted their attention from looking outside. As the pilot became stressed by the noise, particularly as it became ‘quite shrill’, the cockpit fogged up, further reducing the pilot’s ability to see outside.

At that time, GWQ was thermalling and in a right bank at about 40–45°, and had completed four orbits. The front seat pilot sighted a glider approaching from the opposite direction at about the same altitude. They assumed that the glider would join the thermal behind them, in the same direction, and on the opposite side of the orbit, in accordance with normal procedures. The front seat pilot asked the rear seat pilot whether they could see the glider, who responded ‘no’. The FLARM fitted to their glider indicated that there was another glider in close proximity and the rear seat pilot looked outside to see where it was.

The front seat pilot assessed that the approaching glider was not going to manoeuvre to join the thermal or to avoid a collision, so took control of the glider and pushed the stick forwards to descend rapidly. The other glider (CQP) passed overhead.

The pilot of CQP sighted a glider pass below, and estimated there was less than 100 ft vertical separation. Both gliders continued their flight for about another hour after which GWQ landed at Porepunkah and CPQ landed at Mount Beauty without further incident.

Flight data

According to the flight data recorded by the gliders’ flight logger, at 1354:58, CQP was at 3,606 ft and GWQ at 3,523 ft. Four seconds later as the gliders’ paths crossed, CQP was at 3,605 ft and GWQ had descended to 3,458 ft.

FLARM

FLARM is a collision avoidance system that shows other similarly equipped aircraft in the vicinity. The display shows the approximate direction of detected traffic and whether it is above, below or at about the same level (Figure 2).

Figure 2: OZflarm display

Source: OZflarm

According to the FLARM website,

Each FLARM device determines its position and altitude with a highly sensitive state of the art GPS receiver. Based on speed, acceleration, heading, track, turn radius, wind, altitude, vertical speed, configured aircraft type, and other parameters, a very precise projected flight path can be calculated. The flight path is encoded and sent over an encrypted radio channel to all nearby aircraft at least once per second.

At the same time, the FLARM device receives the same encoded flight path from all surrounding aircraft. Using a combination of own and received flight paths, an intelligent motion prediction algorithm calculates a collision risk for each received aircraft based on an integrated risk model. The FLARM device communicates this, together with the direction and altitude difference to the intruding aircraft, to the connected FLARM display. The pilots are then given visual and aural warnings and can take resolutive action.

Pilot comments

Pilot of VH-CQP

The pilot of CQP reported that they had flown gliders fitted with FLARM for 7–8 years and had never heard it make a noise before. This may have been because they had never been close enough to another glider to trigger the alarm before. They were briefed and had a briefing note circulated by the gliding club when they were first installed. The pilot did not think there were any other gliders in the vicinity, and did not associate the alarm with FLARM.

The pilot had a VHF radio with the local area frequency selected, but did not make or hear any broadcasts regarding GWQ.

Pilots of VH-GWQ

The pilot in the front seat of GWQ reported that there were some radio broadcasts at the time, mainly from the glider tug pilots in the circuit at Mount Beauty and Porepunkah. They had not made any broadcasts, and had not heard any from CQP.

The pilot in the rear seat commented that the head and shoulders of the pilot in the front seat obscured their vision immediately ahead at the same level. When the FLARM sounded, rather than looking at the display, they looked outside for the other glider.

The pilot in the rear seat further reported that the FLARM unit in CQP had recently been upgraded to a PowerFlarm. This may have included a new display, and also may have been indicating ADS-B transmissions. Changes to display and aural warnings of the FLARM fitted to CQP may have been confusing for the pilot of CQP.

Safety message

The glider pilots reported that see and avoid was the usual means of maintaining separation from other gliders. It was not uncommon to be in close proximity to other gliders, particularly when thermalling. They did not normally broadcast their position or intentions when thermalling, and expected other glider pilots to adhere to standard procedures.

Avoidance systems such as FLARM can enhace safety in non-controlled airspace by detecting conflicting aircraft also fitted with a compatible system. These assist in alerting pilots to the presence of other aircraft and directing them where to look. The ATSB report Limitations of the See-and-Avoid Principle outlines the major factors that limit the effectiveness of un-alerted see-and-avoid. Insufficient communication between pilots operating in the same area is the most common cause of safety incidents near non-controlled aerodromes.

It is essential that when equipment is installed in an aircraft, pilots have an understanding of its operation and are familiar with its characteristics.

The following publications provide valuable and relevant references for glider pilots:

• Operational Safety Bulletin (OSB) 02/12 - Lookout for Glider Pilots
• Operational Safety Bulletin (OSB) 02 14 - See and Avoid for Glider Pilots

Aviation Short Investigations Bulletin - Issue 51

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

__________

1. An ascending current of air caused by local heating, used by glider pilots to attain height.

What happened

On 3 April 2016, the pilot of a de Havilland DH-82 aeroplane, registered VH-BJE, conducted a 30‑minute scenic flight from Redcliffe Airport, Queensland, with one passenger on board. The weather was fine, with wind was from the east-northeast at less than 8 kt, no precipitation, and the runway was dry.

On returning to Redcliffe, the pilot elected to join the circuit on a mid-field crosswind leg for runway 07. The pilot reported that the approach was normal.

As the aircraft landed, the pilot reported the tail was slightly higher than normal, but the aircraft’s speed was normal. The aircraft wheels touched down at the pilot’s aiming point, about half way along the grass strip to the right of the sealed runway. The pilot reported that the wheels seemed to dig in. The aircraft nose pitched down, the propeller struck the grass runway, and the aircraft rolled over forwards, coming to rest inverted (Figure 1).

The pilot and passenger were uninjured. The aircraft sustained substantial damage.

Figure 1: Accident site showing damage to VH-BJE

Source: Ron Ennis – modified by the ATSB

Pilot comments and experience

At the time of the accident, the pilot had a total of 259.3 hours of aeronautical experience, including 7.9 hours on the aircraft type. The pilot held tailwheel and aerobatic endorsements, obtained in an American Champion/Bellanca Citabria aircraft.

The pilot commented that the ground was a bit soft where the wheels had touched down, but that they had landed there twice previously that day without incident. In future, the pilot would land with a slightly higher nose attitude.

Aviation Short Investigations Bulletin - Issue 50

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

Safety summary

What happened

On 7 April 2016, the pilots of two Robinson R22 helicopters flew from Mossman, Queensland to various fishing locations to the north with a passenger in each helicopter. Late in the afternoon, the pilots commenced the direct return flight to Mossman. However, the pilots encountered weather and winds that slowed their progress and required them to refuel at Cooktown.

The pilots departed Cooktown at last light intending to track via the coast to Mossman. As the flights progressed, the light available from the sun continued to decrease and there was no moon. There were also patches of cloud and rain in the general area.

Shortly after passing Cape Tribulation, in dark night conditions, one of the helicopters, registered VH-YLY (YLY), collided with the sea. The passenger was injured in the accident but was able to reach the shore and notify emergency services. Unaware of the accident, the occupants of the other helicopter continued to Mossman.

A search was initiated and the missing helicopter was located on 9 April 2016 in about 400 m offshore in about 10 m of water. The pilot was not located.

What the ATSB found

The ATSB found that the pilot of YLY, who was only qualified to operate in day-VFR conditions, departed on a night flight and continued towards the destination in deteriorating visibility until inadvertently allowing the helicopter to descend into water.

The ATSB also identified the following other factors that collectively increased risk:

• an unapproved modification attached to the skids of YLY
• exceedance of weight and balance limitations
• non-carriage of life jackets
• incomplete operational information
• overdue calibration checks of the helicopter pitot-static system and altimeter.

Safety message

To avoid the usually fatal consequences of losing visual reference, day-VFR pilots need to plan to arrive at their destination at least 10 minutes before last light and to have a realistic ‘plan B’ to use when it becomes apparent that the intended flight cannot be completed in daylight. A further consideration for pilot decision-making about flying conditions is the degree to which passengers are also exposed to risk.

Key messages from the ATSB Avoidable Accidents series report No.7 highlight that some nights and some terrain are darker than others, and inadvertently flying into instrument meteorological conditions is also harder to avoid at night. Pilots need to be mindful of similar messages provided in pilot operating handbooks that refer to risks associated with loss of visibility and night flight in bad weather.

The occurrence

On the morning of 7 April 2016, the pilot of a Robinson Helicopter Company R22 helicopter, registered VH-YLY (YLY) flew from Mareeba to Mossman, Queensland, to join the pilot of another R22 for a fishing trip (Figure 1). Both pilots were qualified to operate the helicopters on private‑category operations by day under the visual flight rules^[1].

The two pilots departed Mossman at about 0800 EST^[2] with a passenger in each of the two‑seat helicopters. The pilots tracked north to Cooktown to refuel then continued northward to Pipon Island, landing at various coastal locations so they and the passengers could do some fishing. At one of the landing sites the pilots were able to fill the helicopter fuel tanks from a drum of fuel.

By the time the helicopters arrived at Pipon Island, the occupants had caught between 20 and 30 kg of fish, which were carried in a non-standard container attached to the left skid of YLY. After spending some time at Pipon Island, the pilots departed separately somewhere between 1600 and 1700 to return to Mossman. The pilots had used GPS route information and local weather conditions, rather than the required aviation Area Forecast,^[3] to decide that they had sufficient fuel and daylight to make it to Mossman, a direct-track distance of 148 NM (274 km).

Figure 1: Location of Pipon Island with Cooktown and Mossman destinations showing position of VH-YLY accident site south of Cape Tribulation. The inset shows Cape Tribulation relative to far north Queensland

Source: Google Earth and modified by ATSB

During the return flight, squalls and headwinds of about 20 kt were encountered that slowed progress and necessitated a landing at Cooktown to refuel. Relative to the other helicopter, YLY was slower likely due to the aerodynamic drag of the skid‑mounted container, the additional weight of the fish, and doors-off operation.

Recorded fuel transaction information showed the time of fuel uplift at Cooktown occurred at 1836. Given last light for Cooktown was calculated to be 1838 (based on ideal conditions), night conditions existed by the time the pilots were ready to depart. Neither pilot was qualified to fly at night or in low visibility conditions that would require instrument flying. Additionally, the helicopters were not equipped with an artificial horizon instrument and lacked other equipment required for flight at night under Australian regulations.

The passenger in YLY reported he was concerned about the available light and weather conditions and queried the pilot’s intention to continue the flight after Cooktown. Without elaborating, the pilot indicated he intended to continue and the flight (direct-track distance of 60 NM) would only take 45 minutes. None of the pilots or the passengers reported any specific reason to arrive at Mossman that evening. The pilots did not discuss staying in Cooktown.

Both helicopters departed Cooktown at about 1840. A witness who observed the departure reported it was getting dark, which was consistent with it being after last light and no moonlight (local moon-set was 1811). Due to the slower speed of YLY, the other helicopter drew ahead. Every 10 minutes or so, the pilot of the lead helicopter, who was the more experienced pilot, checked in with the pilot of YLY by radio.

According to the pilot in the lead helicopter, and as had been discussed, they flew close to the coast intending to keep an outline of the mountains as a visual reference. In ‘bad conditions’, the proposed method was to ensure the altimeter was accurate relative to sea level and use it to fly not below 250 ft above the water. If the conditions got ‘really bad’, in that it got too dark and the outline of the mountains or sight of the water was being affected, the plan discussed between the pilots was to land on a beach. The pilot of the lead helicopter advised they had done this on previous occasions due to bad weather, though only in daylight.

The coastal route between Cooktown and Mossman has few settlements and from halfway, most of the coastline is part of the Cape Tribulation section of the Daintree National Park. It is a remote area and, as such, there is little or no ground lighting.

Initially, the weather conditions were reported to be clear but about 15-20 minutes into the flight, the pilot of the lead helicopter encountered small squalls with a bit of cloud. After passing Cape Tribulation, the pilot of the lead helicopter radioed the pilot of YLY who advised he had just passed the cape and did not report any difficulties.

The passenger in YLY recalled that at one stage the helicopter descended close to the water before the pilot corrected and climbed. He further stated that visibility decreased until it was dark and the pilot dimmed the cockpit lights to reduce glare off the windscreen. The passenger recalled passing the Cape Tribulation campgrounds and was aware that there were people on the beach as indicated by campfires and a spotlight being waved at the passing helicopters.

To the passenger, it got ‘really dark’ and concerning so he suggested landing on the beach. The pilot did not respond verbally but it appeared to the passenger that they might be descending to land. Suddenly the passenger saw the ocean more clearly followed almost immediately by a ‘massive bang’ as the helicopter impacted the water.

When the passenger regained consciousness, he was strapped into the helicopter on the ocean floor. He was able to release himself, reach the surface, and tread water in a heavy swell. Injuries to a leg and arm restricted swimming but the tide carried him to the beach where he was able to make contact with campers and notify the authorities. Campers had heard an impact and already reported it to police.

About 10 minutes after the radio call near Cape Tribulation, the pilot in the lead helicopter tried unsuccessfully to contact the pilot of YLY. He recalled that, at the time, there was light cloud, mist, showers, and strong winds. The lead pilot said he was concerned about YLY and wanted to turn back but was prevented by limited time, strong winds, and marginal visibility. So the pilot continued to Mossman.

A search was mounted but the missing pilot was not found.

Queensland Police with the assistance of specialist divers located the empty wreckage about 400 m seaward of Noah Beach. The wreckage was not recovered but divers examined the wreckage and recorded underwater video imagery, which was provided to the ATSB (Figure 2).

Figure 2: Underwater image of VH-YLY showing significant damage to the nose and belly panel of the helicopter particularly to the right forward section and loss of the cockpit upper portion

Extensive damage to the right side of the helicopter, including the pilot’s seat belt fitting found torn from its mount, indicated a significant right‑side impact with the water. The main rotor blades and transmission were present and similarly damaged. The tailboom was not identified in the footage and it likely became detached during the accident sequence. The damage to the helicopter and rotor system was consistent with powered flight into the water.

A maintenance release had been issued for YLY authorising VFR Day operation only. A check calibration of the aircraft pitot-static system and altimeter was due in October 2015 and had yet to be certified as complete. As such, the accuracy of the airspeed indicator, vertical speed indicator and altimeter was not assured. A review of the helicopter logbooks did not find any reference to installation of the container to the left skid.

Based on the reported loading of YLY, on departure from Cooktown for Mossman the helicopter was estimated to be at least 35 kg over the maximum gross weight limitation. Although there was no weight and balance data for the skid-mounted container, the longitudinal and lateral centre of gravity were estimated to be outside limits on departure or as fuel was consumed.

Although some of the flying that day included flight over water, the pilots and passengers did not wear life jackets. This was contrary to the regulatory requirement for the occupants of single‑engine aircraft being operated beyond gliding/autorotation distance of land and while below 2,000 ft.

According to the applicable area forecast required for flight planning, in the area of operation east of the ranges and coast, there would be isolated showers with associated low cloud and reduced visibility. The wind was expected to be from the east to south-east at 15 to 20 kt. From 2300, isolated areas of low cloud were expected east of the ranges and coast. This was broadly consistent with the aerodrome forecasts for Cooktown and Cairns, except that the showers and low cloud were due at Cairns from 1700.

The closest official weather observation site to the accident location was at Low Isles, 15 NM (28 km) to the south. At the approximate time of the accident, the wind was from the south-east at 20 kt. No precipitation was recorded during the hour before and after the accident. The extent of cloud coverage was not measured at the site.

The recorded imagery from the Cairns weather radar showed a small area of light rain inland near Cape Tribulation and patches of light to moderate rain off the coast no closer than 15 NM (28 km).

For aviation purposes, night is defined as the period of darkness from last light (end of evening civil twilight) to first light (beginning of morning civil twilight). At last light, in ideal conditions, there will be enough light from the sun for large objects to be seen but no detail. As time passes, light from the sun further diminishes to reach a point where it is insufficient to allow a horizon to be seen at sea level. This point (end of evening nautical twilight) at Cape Tribulation was calculated to be 1919 but high terrain to the west would tend to make it effectively earlier.

The time of the accident was estimated to be 1930, which was about 10 minutes after end of evening nautical twilight.

Safety analysis

The pilots of the two helicopters conducted a series of flights to various fishing locations without incident. However, on the return trip from Pipon Island to Mossman late in the afternoon, the progress was slower than the pilots expected in part due to the prevailing weather conditions. The pilots diverted to Cooktown to refuel and landed about 10 minutes before last light.

As the pilots were only qualified to fly during daylight hours in VFR conditions, there was insufficient time for the pilots to conduct the flight to Mossman within the regulatory  requirements and with an appropriate level of risk. Despite that, the pilots departed Cooktown just after last light for the nominally 45-minute flight to Mossman.

Influences on pilot decision-making are complex and the decisions by both pilots to depart Cooktown after last light are not analysed in depth. In simple terms, the pilots were motivated to reach the intended destination and either did not perceive the high level of risk, or had a high tolerance of that risk.

It is noted that both pilots had reportedly completed other flights in low visibility conditions, including landing on a beach when the conditions required. This may have provided a level of confidence in their ability to conduct the flights at night, which would be misplaced if it was based on their experience in daylight. In response to a draft of this report, the surviving pilot advised that he did not believe the flight was high-risk or that their ‘plan B’ was unrealistic.

As the flights progressed down the coast, the natural light was reducing. By 1919 (local end of nautical twilight), at low level over water and without moonlight or significant artificial lighting, the horizon would technically not be visible. Other factors adversely affecting visibility in the southward direction of flight were the high terrain to the west and potentially cloud and/or rain. In response to a draft of this report, the surviving pilot reiterated that he was able to see the horizon at all times and had sufficient light.

By the time YLY passed Cape Tribulation, the pilot was operating in dark night conditions with little to no terrestrial lighting. When the passenger expressed concerns to the pilot about variations in the helicopter’s height relative to the water, there was no apparent consideration of landing. It is likely that the prospect of landing in an unfamiliar area in darkness and windy conditions was not a favourable option for a pilot operating with minimal visual references. At this point, YLY was over halfway to the destination and turning back to Cooktown in the prevailing conditions was unlikely to be viewed as a realistic option. The pilot may also have been influenced to continue by the progress made by the more experienced pilot ahead of him.

It is not clear how the pilot of YLY was maintaining control of the helicopter. Without an artificial horizon instrument and the training to use it, the pilot was reliant on external reference to a natural horizon or surface features. As the horizon became less distinct during the flight, the pilot presumably maintained visual reference to the coastline and surface of the water. When the pilot dimmed the instrument panel lights to reduce internal glare and reflections, this was apparently necessary to assist with external reference.

Although the method proposed by the pilot of the lead helicopter to maintain height at low level was to use the altimeter, it would have been difficult for the pilot of YLY to monitor the instruments (including the vertical speed indicator) with dimmed cockpit lighting as well as scanning the surrounding surface features. This would be made more difficult by the windy conditions and inherent instability of helicopters.

Shortly after passing Cape Tribulation, the helicopter collided with water in a right skid-low attitude. Given the passenger account that the helicopter was operating normally and the accident occurred without warning, the pilot was probably unaware of the proximity of the water and/or was in the process of losing control of the helicopter. In the dark night conditions, the pilot could have also encountered an area of cloud and/or rain that wasn’t evident in the weather radar image.

The ATSB found that the pilot of YLY, who was only qualified to operate in day-VFR conditions, departed on a night flight and continued towards the destination in deteriorating visibility until inadvertently allowing the helicopter to descend into water.

It is concerning that some day-VFR helicopter pilots continue to operate illegally and unsafely by flying at night. Although pilots have done this with mixed outcomes, as the two pilots involved in this occurrence experienced, the risks of such operation are extremely high.

This was demonstrated on 24 April 2011, when an R44 registered VH-RUR, collided with the sea while on approach at a reduced airspeed to a helicopter landing site. The helicopter was being flown after last light by a pilot who was not approved, nor was the helicopter equipped to fly at night. The ATSB found that the flight was commenced with insufficient daylight to complete the planned flight under the day visual flight rules. Although the pilot survived, they had no visual reference with the sea surface immediately before the helicopter inadvertently descended into the water (ATSB Transport Safety Report AO-2011-051).

In similar circumstances to this occurrence, on 25 August 2014, the pilots of two R22 helicopters were delayed and were operating in dark night conditions to reach the planned destination. One of the pilots inadvertently allowed the helicopter to descend into terrain and was fatally injured (ATSB Transport Safety Report AO-2014-144).

The ATSB Avoidable Accidents series report No. 7 refers to accidents and the risks associated with visual flight at night. One of that report’s key messages was that some nights and some terrain are darker than others, and inadvertently flying into instrument meteorological conditions is also harder to avoid at night.

The helicopter manufacturer, Robinson Helicopter Company (RHC), included safety notices in the R22 Pilot’s Operating Handbook that target specific risks relating to loss of visibility (RHC Safety Notice SN-18) and night flight in marginal weather conditions (RHC Safety Notice SN-26). Copies of the safety notices referenced in this section are available on the RHC website.

To avoid the often fatal consequences of losing visual reference, day-VFR pilots need to plan to arrive at their destination at least 10 minutes before last light and to have a realistic ‘plan B’ to use when it becomes apparent that the intended flight cannot be completed in daylight. A further consideration for pilot decision-making about flying conditions is the degree to which passengers are exposed to risk. 

In addition to the night flying risks, the ATSB identified the following other aspects of the operation that were not considered to be contributing safety factors but collectively increased risk:

• The unapproved skid-mounted container increased the aerodynamic drag of the helicopter, increased capacity for overloading, affected lateral balance, and had implications for skid down-load and vibration-related loading (RHC Safety Notice SN-13 discusses the risk of attaching items to the helicopter skids).
• The weight and balance of the helicopter during parts of the flight exceeded the limitations with associated adverse effects on handling, performance and component fatigue (RHC Safety Notice SN-37).
• For over-water operations, non-carriage of life jackets compromised survivability following an accident involving a collision with water (such as this occurrence) or a ditching.
• The pilots made operational decisions without taking aviation forecasts and reports or the availability of celestial or terrestrial lighting into account.
• Operation of YLY with overdue calibration checks of the pitot-static system and altimeter increased the risk of unreliable instrument indications that could be problematic in low visibility conditions.

Findings

From the evidence available, the following finding is made with respect to the collision with water of a Robinson Helicopter Company R22 helicopter, registered VH-YLY that occurred near Cape Tribulation, Queensland, on 7 April 2016. These findings should not be read as apportioning blame or liability to any particular organisation or individual.

Contributing factor

• The pilot of YLY, who was only qualified to operate in day-VFR conditions, departed on a night flight and continued towards the destination in deteriorating visibility until inadvertently allowing the helicopter to descend into water.

__________

1. Visual Flight Rules (VFR) are a set of regulations which allow a pilot to only operate an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going.
2. Eastern Standard Time (EST): Coordinated Universal Time (UTC) + 10 hours.
3. Area forecast (ARFOR): routine forecasts for designated areas and amendments when prescribed criteria are satisfied. Australia is subdivided into a number of forecast areas.

Sources and submissions

Sources of information

The sources of information during the investigation included the:

• surviving occupants of the two helicopters
• Cairns Forensic Crash Unit, Queensland Police
• the Bureau of Meteorology
• the Civil Aviation Safety Authority (CASA)
• Airservices Australia
• Geoscience Australia

References

ATSB (2013), Avoidable Accidents No. 7. Visual flight at night accidents: What you can’t see can still hurt you, ATSB, Canberra, Australia.

Robinson Helicopter Company (Rev. 1994), Safety Notice SN-13 Do not attach items to the skids.

Robinson Helicopter Company (Rev. 1994), Safety Notice SN-18 Loss of visibility can be fatal.

Robinson Helicopter Company (Rev. 1994), Safety Notice SN-26 Night flight plus bad weather can be deadly.

Robinson Helicopter Company (2001), Safety Notice SN-37 Exceeding approved limitations can be fatal.

Submissions

Under Part 4, Division 2 (Investigation Reports), Section 26 of the Transport Safety Investigation Act 2003 (the Act), the Australian Transport Safety Bureau (ATSB) may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. Section 26 (1) (a) of the Act allows a person receiving a draft report to make submissions to the ATSB about the draft report.

A draft of this report was provided to the other R22 pilot and CASA.

Submissions were received from the other R22 pilot and CASA. The submissions were reviewed and where considered appropriate, the text of the report was amended accordingly.

Purpose of safety investigations & publishing information

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through:  identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2017 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

What happened

On 29 March 2016, the pilot of a Piper PA-28-181 aeroplane, registered VH-BDB, conducted a private flight from Aldinga, South Australia, to Hay, New South Wales (NSW), under the visual flight rules (VFR).^[1] After refuelling in Hay, the pilot planned the next VFR flight to Bankstown, NSW.

The pilot obtained the latest weather forecast for the area, and for Bankstown and Bathurst airports. As the weather forecast for Bankstown indicated conditions would be marginal for VFR flight, the pilot planned for an alternate landing at Bathurst.

The aircraft departed Hay and tracked towards Katoomba, NSW. When about 30 minutes from Katoomba, the pilot, who was the only person on board, contacted a flight instructor who was on the ground at Bankstown Airport for an appraisal of the current weather conditions. Based on the forecast and the instructor’s comments, the pilot continued an indirect track towards Glenbrook via Katoomba and then planned to track to Bankstown (Figure 1).

Figure 1: Radar image annotated with approximate track of VH-BDB and relevant locations

Source: Airservices Australia – annotated by the ATSB

At about 1511, the pilot saw the cloud appear to be closing in on the planned track ahead. The pilot scanned from the left to the right and assessed that it would not be possible to continue on their current track and remain clear of cloud, so commenced a right turn. The aircraft then entered cloud.

At about 1512, the pilot contacted Bankstown Tower air traffic control and declared a mayday.^[2] By the time the pilot had completed the transmission, the aircraft had flown clear of the cloud. About 90 seconds later, the pilot advised the tower controller that they had stabilised flight and that the aircraft was then at 3,000 ft tracking into the Richmond restricted airspace without a clearance, to remain clear of cloud. According to the radar data, the aircraft entered Richmond airspace at about 1515, on climb passing 3,800 ft. The tower controller coordinated with Sydney Approach to provide the pilot with a clearance, then advised the pilot to contact Sydney Approach for assistance.

At about 1516, the approach controller assigned the aircraft a discrete transponder code, and asked the pilot to advise their current situation regarding visibility, and their intentions. The pilot responded that they were then on top of cloud and unable to find a way down. The pilot elected to continue tracking to the north where the weather was clearer and away from the rising ground to the west. The aircraft tracked north and then north-east (Figure 1).

The pilot then advised that the aircraft’s current altitude was 5,000 ft and climbing. The controller responded with a clearance to continue on their current heading at 5,000 ft, which was well above the radar lowest safe altitude^[3] on that track, and to advise if a change in level or heading was required. The controller subsequently advised the pilot to remain in visual meteorological conditions^[4] (VMC) and to deviate around cloud if necessary.

At about 1519, the controller contacted Richmond and Williamtown air traffic control to obtain updated weather information to assist the pilot. The controller at Williamtown responded that it was hard to tell what the cloud was like due to the rain, but that there was a lower cloud band to the west than to the north-east.

About 2 minutes later, the pilot advised the controller that they could see the ground and were assessing their options to get down under the cloud. The controller asked the pilot to confirm that they could maintain separation from the cloud and terrain while descending through the gap.

The pilot then advised that they required a left turn to remain clear of cloud, and the controller asked the pilot to confirm they were maintaining 5,000 ft as the transponder was not displaying altitude. The pilot realised that they had inadvertently selected the altitude mode on the transponder off and switched it on, then advised the controller they were now maintaining 5,500 ft and required further left turn.

The aircraft was then heading west, and the pilot stated to the controller that their best option would be to get over the escarpment and divert to Bathurst. The controller asked the pilot what the aircraft’s remaining fuel endurance was, but the pilot was unable to calculate the endurance due to the high workload to remain clear of cloud.

At about 1525, the aircraft was 10 NM north of Richmond aerodrome. The pilot advised that there was a large opening to their right and advised that they were turning onto a heading of 050° and shortly after, advised they were commencing a descent. The controller responded that the radar lowest safe altitude in the area was 3,500 ft and asked the pilot to confirm they were able to maintain visual contact with terrain on descent. The pilot confirmed they could maintain VMC through the gap in the cloud and was then cleared to descend visual with terrain.

At about 1527, the controller advised that they had confirmation of visual conditions towards Bathurst. The pilot stated that they would assess over the next 5 miles. In response to a request for their endurance, the pilot stated that they were busy keeping clear of cloud, and would get back with the endurance shortly. The aircraft was then tracking north-east at 5,000 ft, and descended to 4,200 ft by about 1529. The controller then advised that the radar lowest safe altitude on the aircraft’s track was now 2,500 ft and confirmed the pilot was still visual with terrain. A minute later, the aircraft had descended to about 3,500 ft, and the controller advised that the radar lowest safe altitude was 2,700 ft on the aircraft’s current heading, and again asked the pilot to confirm they were still visual with terrain and that at their current rate of descent, they had plenty of space to remain in VMC. The pilot responded that they were still visual with terrain but needed a left turn to remain clear of cloud. The controller responded that the pilot could turn as required, and advised the pilot that the main thing was to maintain in VMC. The aircraft descended to 3,000 ft during the left turn.

At about 1532, the pilot stated that Bathurst was ‘starting to look good’. The controller again reminded the pilot to maintain VMC at all times. The pilot responded that the gaps were closing up every time they approached one. The aircraft climbed and tracked west-south-west. The controller asked whether the pilot was using carburettor heat. Then the controller advised that the weather was CAVOK^[5] at Bathurst and probably just climbing above the cloud, maintaining VMC and tracking to Bathurst would be the best plan from the information available at that stage. Again, the controller stated that the main thing was to stay in VMC.

The pilot then turned the aircraft onto a heading direct to Bathurst. The controller advised that they were now well above the lowest safe altitude in the area, and requested the fuel endurance. The pilot advised that they had sufficient fuel endurance to Bathurst with 45 minutes reserve and at present, were focused on flying the aircraft but could work out the actual endurance once clear of the cloud.

At about 1538, the controller advised that the aircraft had about 56 miles to run to Bathurst and was heading in a good general direction. The pilot reported that they had 5 km terrain visibility and were going to be doing a bit of cloud dodging to maintain the altitude (the aircraft was still at 6,700 ft).

At 1542, the controller asked whether they were visual with terrain in any direction and the pilot responded that they were visual with terrain directly below and behind, and bits ahead through quite a large gap in the cloud. The controller advised that there was report of overcast at Bathurst at 9,500 ft. Three minutes later, the controller asked how the weather directly in front looked, and whether the pilot had seen anywhere they might be able to descend to Bathurst. The pilot responded that everything was opening up ahead.

The aircraft exited controlled airspace at about 1546 tracking direct to Bathurst at 6,700 ft. At about 1550, the pilot reported they were commencing descent into Bathurst. The controller confirmed that the pilot would be able to maintain visual with terrain and advised the pilot to contact air traffic control on the area frequency.

The aircraft landed on runway 17 at Bathurst without further incident.

Weather information

Aerodrome terminal information service

The aerodrome terminal information service (ATIS)^[6] current at Bankstown around the time of the incident included that pilots were to expect an instrument approach, the runways were wet, visibility was 5,000 m in rain, and there were layers of cloud with bases at 1,500 and 2,000 ft.

Forecast

The relevant area forecasts valid for the flight included Area 20 and Area 21. The forecast weather was for multiple layers of cloud, including low cloud with a base of 1,000 ft AMSL. The visibility included reducing to 4,000 m in showers of rain. At Mt Victoria, about 9 NM north-northwest of Katoomba, there was a forecast of cloud on the ground and showers of rain.

The forecast for Bankstown Airport included showers of rain with cloud bases at about 2,000 ft, with the chance of lower cloud at 1,000 ft. Bathurst Airport forecast included precipitation and the chance of low cloud 800 ft above the aerodrome.

Pilot comments

The pilot provided the following comments:

• The aircraft was only in cloud for about 3 to 5 seconds, and the pilot felt confident in using the instruments to maintain control of the aircraft.
• When the aircraft entered cloud, instead of turning right, in hindsight the pilot thought they should have moved the aircraft to the right of the corridor between clouds and then turned left to remain clear of cloud.
• Air traffic control was ‘brilliant’ – the pilot did not feel alone, and was looked after. The controller provided the radar lowest safe altitude in the location, and the pilot found it reassuring. The visibility was about 5–6 km, and it was helpful to know that the weather was more open ahead.
• The weather conditions were in accordance with the forecast to Katoomba, but around Glenbrook, the pilot was expecting a cloud base of about 1,500 to 2,000 ft above ground level (AGL), but it was more like 500 ft AGL.
• Based on the forecast, the pilot assessed that the weather conditions were marginal, but it may be possible to land at Bankstown. The pilot had planned to divert to Bathurst if it did not look possible to get to Bankstown in VMC.

Safety message

This incident highlights the benefits of seeking assistance from ATC when a pilot is in difficulty. It enabled ATC to provide appropriate assistance including clearance into controlled airspace, and to prioritise their resources. Airservices Australia commented that under the circumstances, it would have been more effective for the pilot to broadcast a MAYDAY on the area frequency than on Bankstown Tower frequency. On the area frequency, ATC would have been able to provide more immediate and direct assistance.

The ATSB SafetyWatch highlights the broad safety concerns that come out of our investigation findings and from the occurrence data reported to us by industry. Flying with reduced visual cues such as in this occurrence remains one of the ATSB’s major safety concerns.

The ATSB publication Accidents involving Visual Flight Rules pilots in Instrument Meteorological Conditions, lists three key messages for pilots:

• Avoiding deteriorating weather or instrument meteorological conditions (IMC)^[7] requires thorough pre-flight planning, having alternate plans in case of an unexpected deterioration in the weather, and making timely and decisions to turn back or divert.
• Pressing on into IMC with no instrument rating carries a significant risk of severe spatial disorientation due to powerful and misleading orientation sensations in the absence of visual cues. Disorientation can affect any pilot, no matter what their level of experience.

VFR pilots are encouraged to use a personal minimums checklist to help identify and manage risk factors that include marginal weather conditions.

Also available from CASA’s online store are:

Weather to Fly DVD – highlights the dangers of flying in cloud and ways to avoid VFR into IMC.

Flight Planning – always thinking ahead. A flight-planning guide designed to help you in planning and conducting your flight. This guide includes a personal minimums checklist.

A similar incident occurred on 21 April 2016, and the pilot advised ATC they had entered cloud and requested assistance. The controller identified the aircraft using ADS-B and provided heading and turn guidance to the pilot. The aircraft landed safely.

Aviation Short Investigations Bulletin - Issue 49

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

__________

1. Visual flight rules (VFR) are a set of regulations which allow a pilot to only operate an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going.
2. Mayday is an internationally recognised radio call for urgent assistance.
3. Lowest safe altitude (LSALT) is the lowest altitude which will provide safe terrain clearance at a given place.
4. VMC is determined by the minimum flight visibility and minimum horizontal and vertical distances from cloud that the pilot in command (PIC) must maintain within certain classes of airspace..
5. Ceiling and visibility OK, meaning that the visibility, cloud and present weather are better than prescribed conditions. For an aerodrome weather report, those conditions are visibility 10 km or more, no significant cloud below 5,000 ft or cumulonimbus cloud and no other significant weather within 9 km of the aerodrome.
6. An automated pre-recorded transmission indicating the prevailing weather conditions at the aerodrome and other relevant operational information for arriving and departing aircraft.
7. Instrument meteorological conditions (IMC) describes weather conditions that require pilots to fly primarily by reference to instruments, and therefore under Instrument Flight Rules (IFR), rather than by outside visual references. Typically, this means flying in cloud or limited visibility.

What happened

On 31 March 2016, an Airbus A330-323, registered 9M-MTB and operated by Malaysia Airlines Berhad (Malaysia Airlines), was being prepared and boarded for a flight from Melbourne Airport, Victoria, to Kuala Lumpur, Malaysia. The captain engaged the aircraft’s park brake before carrying out an external inspection of the aircraft. The resulting lit park brake indicator light on the nose landing gear led the aircraft maintenance engineer to assume that the park brake would remain on. Thinking that the aircraft would remain secure, the maintenance engineer removed the main landing gear chocks out of sequence with the relevant procedure and without informing the others in the ground crew. The ground crews did not check the main gear chocks before removing the nose gear chocks to attach the tow tractor to the nose gear. Unaware that no chocks were in place, and out of sequence with the relevant procedure, the captain released the park brake on return to the flight deck. The aircraft rolled back about 3 m and struck the aerobridge. The aircraft’s forward-left door and hinges, and the aerobridge were damaged. There were no injuries.

What the ATSB found

The ATSB found that the ground and flight crew procedures were not well harmonised, leading to reduced cohesion between the crews, and that the tractor operator’s procedures did not match the way tasks were carried out locally. These problems reduced the likelihood that the respective procedures would be followed correctly. In addition, the flight crew and engineers did not explicitly convey their actions and intentions to the others, resulting in a number of missed opportunities to discover the resulting procedural errors.

What's been done as a result

The engineering company, tractor operator and Malaysia Airlines each planned or initiated safety action in response to this occurrence. The engineering company introduced standard procedures and initiated periodic operational safety inspections at all ports. The tractor operator developed a written procedure to incorporate local differences in work practices and improve coordination. Malaysia Airlines reported that it was planning to amend its procedures so that flight crews advise ground crews whenever the park brake is about to be released. As an interim measure, Malaysia Airlines sent A330 flight crews a reminder to communicate with ground crews before releasing the park brake to verify that chocks are in place.

Safety message

The ATSB stresses the importance of organisations ensuring that ground and flight crew procedures are harmonised to increase the likelihood that potential problems or mistakes are detected before causing harm. It is also important that local variations to procedures are formalised to reduce the risk of the inconsistent completion of tasks, and to improve the organisation’s ability to identify and address potential safety concerns. In addition, the ATSB encourages crews to highlight any procedural problems to their operator in order for them to be reviewed and enhanced as appropriate.

Importantly, when about to perform a key action like removing chocks or releasing the park brake, crews should consider checking with others to identify potential conflicts between tasks. This can reduce the risk of unintentional aircraft movement.

The occurrence

Sequence of events

On 31 March 2016, an Airbus A330-323, registered 9M-MTB and operated by Malaysia Airlines Berhad (Malaysia Airlines), was being prepared and boarded for a flight from Melbourne Airport, Victoria, to Kuala Lumpur, Malaysia. The aircraft had been parked in the bay for several hours following its previous flight, and was secured using wheel chocks under the left main and nose landing gears.

An engineering company provided an aircraft maintenance engineer (AME) and a licenced aircraft maintenance engineer (LAME) to prepare the aircraft for departure. A third company provided a towbarless tractor^[1] and driver for pushback.^[2] A technician was also refuelling the aircraft using a fuel truck parked under the aircraft’s wing. Ground crews could communicate with the flight crew via a headset.

At 0037 Eastern Daylight-saving Time^[3], the aircraft captain engaged the park brake before disembarking to perform a pre-flight external inspection of the aircraft. The park brake had to be set to check the brake wear indicators and could only be controlled from the flight deck. A closed-circuit television recording showed the captain performing the inspection from 0043 to 0048.

Shortly after the captain checked the main landing gear chocks, the AME removed them from the left main landing gear in preparation for pushback. The AME was aware that this step was not in accordance with the normal sequence for pushback with a towbarless tractor, but thought that the aircraft would be secure because the:

• nose landing gear chocks were installed
• park brake indicator light on the nose landing gear had been on when it was recently checked by the AME, consistent with the brake being engaged (Figure 1).

Figure 1: Nose landing gear showing the aircraft’s park brake indicator light (note the wheel chocks in place)

Source: ATSB

Shortly after, the tractor driver arrived at the bay and boarded the tractor. The driver prepared the vehicle for docking to the aircraft’s nose landing gear. The tractor driver reported being unable to see whether the main landing gear chocks were in place due to the shadowing under the aircraft.

At 0051:03, the LAME started to remove the nose chocks so that the towbarless tractor could be docked. The AME assisted the LAME and together they finished removing the chocks at 0051:14. Both then moved off under the aerobridge, which was still in use by boarding crews and passengers. The closed-circuit television recording showed the refueller disconnecting the refuelling equipment from the aircraft’s under-wing filler point at about the same time as the nose chocks were removed.

The driver began to move the towbarless tractor into position to engage the nose landing gear at 0051:18. The closed-circuit television recording showed that the park brake indicator light turned off at 0051:21. This aligned with the flight crew’s recollection that the captain released the park brake on return to the flight deck. The captain later reported always doing this, expecting that the ground crews would inform him when it was necessary to apply the brake.

At 0051:27, as the towbarless tractor moved towards the nose landing gear, the aircraft began to move very slowly backwards. The refueller lowered the fuel truck’s lift a few seconds after the aircraft started moving. The towbarless tractor driver did not notice the aircraft’s movement at first. He continued forward and stopped when the tractor made contact with the aircraft’s nose gear tyres, then drove forward for another 3 seconds. This second movement was probably because the driver noticed the increasing distance between the tractor and the aircraft and automatically tried to bring them closer. The driver did not initially recognise that the situation was abnormal.

The aircraft’s slow movement was not immediately obvious to the flight or ground crews. The aircraft stopped after coming into contact with the aerobridge, having rolled backwards about 3 m in 22 seconds. Hearing the noise and realising that the aircraft had moved, the LAME radioed the flight crew to set the park brake. The captain completed this action at 0052:09.

The aircraft’s forward-left door was dislocated by the contact with the aerobridge (Figure 2). The door, hinges, and aerobridge were damaged and there was slight indentation of the fuselage skin forward of the door. There was no major structural damage. There were no injuries.

Figure 2: The aircraft’s forward fuselage showing the dislocated forward-left door. The slight indentation in the fuselage skin forward of the door is not visible. The aerobridge is shown retracted from its position when struck by the aircraft

Source: Melbourne Airport, modified by the ATSB

Pushback procedures

Engineer procedures

The engineering company used Malaysia Airlines procedures for ground handling. The procedure for the departure stage of a transit check included a step to remove all of the chocks after the aerobridge is detached from the aircraft. The procedure for pushback stated that ‘Chocks should not be removed from the main-gear until the tractor is fully secured to the nose‑gear’. It did not contain guidance for coordinating with a tractor driver.

Tractor operator procedures

The tractor operator used a set of written procedures as the basis for activities that varied across the organisation depending on local arrangements. Workers were trained according to these local requirements.

The written procedure for pushback with a towbarless tractor showed photographs of the pushback activity that included steps for a ‘walk-around check’. It also included confirming that the:

• ‘main gear [was] chocked’ prior to docking the tractor with the aircraft’s nose wheels
• ‘Chocks should not be removed from the main-gear until the tractor is fully secured to the nose-gear and brakes on [the] tractor set.’

At Melbourne Airport, these steps were omitted in practice, because the tractor operator’s work arrangements there did not include management of the wheel chocks. The procedure did not describe how a driver should coordinate with other ground crews when docking the tractor to the aircraft.

Flight crew procedures

The flight crew procedures included steps to:

• set the park brake before carrying out an external inspection of the aircraft
• check the park brake is set and release it only if the brakes are hot (that is, soon after landing) and chocks are in place
• release the park brake after all aircraft doors are closed, pushback clearance is received from air traffic control and ground crew readiness is confirmed.

The procedures did not provide guidance or instruction on how to coordinate park brake release with ground crews.

__________

1. A towbarless tractor has a mechanism that grips and lifts the aircraft’s nose wheels. It cannot be docked with nose landing gear chocks in place. A conventional tractor uses a towbar to attach to the nose landing gear and chocks can be in place at that time.
2. Moving an aircraft from its parking position to a taxi position using specialised ground support equipment.
3. Eastern Daylight-saving Time (EDT) was Coordinated Universal Time (UTC) + 10 hours.

Safety analysis

Explanation of the occurrence

The aircraft’s park brake was set for the captain’s external inspection of the aircraft. The resulting illumination of the park brake indicator light on the nose landing gear led the aircraft maintenance engineer to assume that it would remain set, though this was not confirmed with the flight crew. Thinking that the aircraft would remain secure, the aircraft maintenance engineer removed the main landing gear chocks.

Subsequently, the ground crews did not check the main landing gear chocks before the engineers removed the nose landing gear chocks to dock the towbarless tractor. The tractor operator’s written procedure included a step to check the main landing gear chocks, but in practice, the step was omitted at Melbourne Airport because of a local variation in the way the work was conducted. In addition, there was no corresponding step in the engineers’ procedures. As a result, the absence of main gear chocks remained undetected.

Separately, the aircraft captain was unaware that the docking process was underway and that no chocks were in place. Although the flight crew procedures stated that the park brake should only be released when the wheel brakes were hot (generally only shortly after landing), or after the aircraft doors were closed and with ground crew clearance, the captain released the park brake on return to the flight deck. In the absence of any braking mechanism, the aircraft commenced moving until it struck the aerobridge.

Lessons for effective teamwork

This occurrence highlights the importance of organisations ensuring that ground and flight crew procedures are harmonised to increase the likelihood that potential problems or mistakes are detected before causing harm, and of affected crews applying those procedures consistently. In addition, it is important that local variations to procedures are formalised to reduce the risk of the inconsistent completion of tasks, and improve the organisation’s ability to identify and address potential safety concerns.

Also highlighted is the importance of crews, when about to perform a key action, considering a check with others to identify potential conflicts between tasks. In this instance, such a check before removing chocks or releasing the park brake would likely have reduced the risk of unintentional aircraft movement.

Findings

From the evidence available, the following findings are made with respect to the ground handling occurrence involving Airbus A330, registered 9M-MTB and operated by Malaysia Airlines Berhad, which occurred at Melbourne Airport, Victoria on 31 March 2016. These findings should not be read as apportioning blame or liability to any particular organisation or individual.

Contributing factors

• The aircraft maintenance engineer removed the main landing gear chocks before the towbarless tractor was secured to the aircraft and out of sequence with the normal operating procedures.
• Consistent with local practices, neither the engineers nor the tractor driver checked that the main landing gear chocks were in place before attempting to dock the towbarless tractor to the aircraft.
• The aircraft captain released the park brake out of sequence with the normal operating procedures.

Other factors that increased risk

• The procedures provided to ground and flight crews by Malaysia Airlines Berhad and the towbarless tractor operator did not provide clear guidance or instruction on coordinating activities related to pushback and, in the case of the tractor operator, were informally replaced by local procedures. [Safety Issue]

Safety issues and actions

The safety issue identified during this investigation are listed in the Findings and Safety issues and actions sections of this report. The ATSB expects that all safety issues identified by the investigation should be addressed by the relevant organisation(s). In addressing those issues, the ATSB prefers to encourage relevant organisation(s) to proactively initiate safety action, rather than to issue formal safety recommendations or safety advisory notices.

All of the directly involved parties were provided with a draft report and invited to provide submissions. As part of that process, each organisation was asked to communicate what safety actions, if any, they had carried out or were planning to carry out in relation to each safety issue relevant to their organisation.

Descriptions of each safety issue, and any associated safety recommendations, are detailed below. Click the link to read the full safety issue description, including the issue status and any safety action/s taken. Safety issues and actions are updated on this website when safety issue owners provide further information concerning the implementation of safety action.

Coordination of activities related to pushback

Safety Issue number: AO-2016-028-SI-01

The procedures provided to ground and flight crews by Malaysia Airlines Berhad and the towbarless tractor operator did not provide clear guidance or instruction on coordinating activities related to pushback and, in the case of the tractor operator, were informally replaced by local procedures.

ATSB Safety Advisory Notice: AO-2016-028-SAN-006

Additional safety action

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk.

Action number: AO-2016-028-NSA-001

On 10 June 2016, the ATSB was advised by Aircraft Maintenance Services Australia (AMSA), the engineering organisation, of the following proactive safety action in response to this occurrence:

• The engineering team that day received retraining in pre-departure and pushback operations. This included refamiliarisation with documented procedures, practical assessment and a requirement to perform a team safety brief on lessons learned.
• AMSA began introducing standard aircraft arrival, turnaround and departure procedures to all ports. This will ensure that practices are standardised and that they are over and above client’s
  requirements.
• AMSA commenced periodic operational safety inspections at all ports. These inspections include assessments of the standard procedures to identify opportunities for improvement.

Purpose of safety investigations & publishing information

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

What happened

On 21 March 2016, at about 1200 Eastern Standard Time (EST), the pilot of a Robinson R22 helicopter, registered VH-RGY, prepared to conduct a private ferry flight from Richmond Airport to Bow Park Station, Queensland. The pilot was the only person on board. The helicopter had been parked at the airport for 12 days, with the doors on.

As the pilot rolled the throttle on to start the helicopter’s engine, the pilot discovered the adhesive holding the foam cover of the throttle twist grip had deteriorated and become like grease (Figure 1). The pilot then slid the cover forwards on the collective^[1] control to grip the steel column.

Figure 1: Cockpit of VH-RGY

Source: Pilot

After starting the engine, the driver of the vehicle that had taken the pilot to the airport radioed to tell the pilot that the pilot’s drink bottle was still in the vehicle, and that they would meet the pilot with the drink bottle at the airport exclusion fence.

The pilot reported that they looped the bungee cord fitted to the helicopter over the collective control. The pilot then exited the helicopter, leaving the engine running and the rotor blades turning, and walked about 4 m to the fence. Within about 30 seconds, the pilot heard the helicopter engine RPM increase, and turned and ran back towards the helicopter. The pilot and driver then observed the helicopter rotate away from the direction of the pilot, lift up, into and over the fence and land on its side on the other side of the fence, damaging the fence.

The helicopter sustained substantial damage (Figure 2). The pilot, who was outside of the helicopter was uninjured.

Figure 2: Damage to VH-RGY (after removal from accident site)

Source: Queensland Police Service

Pilot comments

The pilot reported that they had not had any issues with the adhesive before, despite operating in temperatures over 40 °C, but they did not usually have the doors on. However, even though the temperature was about 35 ⁰C on the day of the accident, the helicopter had been parked for 12 days with the doors on, and the temperature inside the cabin was much hotter. Additionally, there had been rain during the period the helicopter was parked at the airport, increasing the humidity inside the cabin. The pilot believed that the temperature (and possibly combined with high humidity) inside the helicopter must have exceeded the adhesive’s limit. The pilot was unsure whether the adhesive, which had been applied during a rebuild of the helicopter about two years earlier, was the approved adhesive for the grip.

The pilot assessed that because the grip had slid forwards on the collective control, the bungee cord may not have been far enough over the steel column, and it then slid further forwards, allowing the collective to rise, and the helicopter then lifted off.

Adhesive for grip

The R22 Illustrated Parts Catalogue specified Part Number B270-15 Adhesive to be used to install the grip. The specified adhesive was clear, and was manufactured by 3M, with part number 2262. According to the Technical Data for 3M Plastic Adhesive 2262, when the adhesive was tested for ‘plus 7 days’ at 140 °F (60 °C), it failed ‘in adhesion to the indicated substrate (steel)’.

Given the helicopter was parked for over 7 days, with doors on and in hot and humid conditions, this testing suggests that if the approved adhesive was used on the collective grip, it was likely to fail.

Helicopter manufacturer comments

A representative from Robinson Helicopter Company (RHC) advised that the bungee cord was not an RHC installation, nor part of the type design. The post-accident photo (Figure 1) shows that the collective friction knob was in the OFF position, which indicates that the pilot had not applied it. (When tightened to the ‘locked’ position, the collective friction knob is designed to prevent the collective from moving from the position it was locked in.) However, they emphasised that the safest way to prevent similar incidents is to never leave the flight controls unattended while the engine is running.

They had received no other reports of similar events with the grip adhesive. They also commented that a thorough pre-flight check would likely alert the pilot to any issue with the collective grip.

Safety message

Pre-flight checks are designed to ensure the helicopter is capable of operating correctly. To ensure safety of flight, any discovery of an unservicability should be dealt with before flight.

Leaving any vehicle unattended with the engine running carries considerable risk. The Normal Procedures in the R22 Pilot’s Operating Handbook (POH) includes the caution: ‘Never leave helicopter flight controls unattended while engine is running.’ The POH also includes a number of important safety tips and notices. One safety notice with relevance to this accident is Safety Notice 17, which includes the following text:

NEVER EXIT HELICOPTER WITH ENGINE RUNNING

Several accidents have occurred when pilots momentarily left their helicopters unattended with the engine running and rotors turning. The collective can creep up, increasing both pitch and throttle, allowing the helicopter to lift off or roll out of control.

Aviation Short Investigations Bulletin - Issue 49

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

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1. A primary helicopter flight control that simultaneously affects the pitch of all blades of a lifting rotor. Collective input is the main control for vertical velocity. The collective control of the Robinson R22 incorporates a throttle mechanism designed to increase engine revolutions per minute (RPM) automatically as collective is applied.

What happened

On 25 March 2016, Bell 206B JetRanger helicopter, registered VH-WHU, struck a powerline while spraying cane fields about 5 km south-west of Carmila, Queensland. During the accident sequence, the helicopter’s tail rotor and vertical stabiliser assembly separated from the helicopter. The helicopter collided with terrain and was destroyed by impact forces and a post‑impact fire. The pilot was fatally injured.

What the ATSB found

The ATSB found that the helicopter was equipped with upper and lower wirestrike protection system equipment and four-point safety harnesses. The pilot was wearing an aviation flying helmet. While not preventing fatal injuries on this occasion, these safety enhancements generally reduce risk and increase the possibility of surviving a collision.

The ATSB also found that the inherent difficulty in visually detecting powerlines was exacerbated in this case by the outer two supporting power poles being masked by trees. There was also a low-contrast background that included cane fields, rising terrain and a tree-lined creek. In combination, these features negated a number of visual cues normally associated by pilots with the location of powerlines. This increased the difficulty of the pilot seeing the wires, and reduced the time available to take action once the powerline was located.

Safety message

Aerial application is conducted at low level, where there is an elevated risk of collision with terrain, man-made structures and wildlife. Pilot training, experience, pre-flight preparation and planning and fatigue management are important means to reduce risk.

The Australian aviation industry has invested heavily in an effort to minimise the risk associated with low-level aerial application. This includes the:

• the Aerial Application Association of Australia Ltd. (previously Aerial Agricultural Association of Australia Ltd.), which has written a number of manuals (available at www.aerialag.com.au), conducted training in aerial application, facilitated access to available wire databases and taken safety action to increase the high visibility marking of wires
• operators, who develop and include risk mitigation strategies in their operations manuals
• Civil Aviation Safety Authority, which issues associated regulations, publications (available at www.casa.gov.au), conducts workshops and carries out operator surveillance aimed at addressing the risks associated with low-level aerial application operations
• ATSB, which has investigated numerous aerial application accidents and issued public reports in an effort to enhance safety in those operations.

Despite those efforts and requirements, wirestrikes continue to occur in low-level aerial application operations. It is therefore prudent, when planning and/or conducting aerial application operations, for pilots and operators to learn from other occurrences and accidents, and continue to apply that knowledge to reduce risks to their operations.

Photograph VH-WHU

Sources and submissions

Sources of information

The sources of information during the investigation included the:

• operator of VH-WHU
• property owner
• Civil Aviation Safety Authority
• Queensland Police.

References

The Aerial Application Association of Australia Ltd., Application Pilots Manual 3rd edition

Australian Government. Australian Transport Safety Bureau, March 2013, Avoidable Accidents No.6, Experience won’t always save you, Pilot experience is not always a protection against an accident. Research AR-2012-035

Australian Government. Australian Transport Safety Bureau, 2014, Avoidable Accidents No. 2, Wirestrike involving known wires: A manageable aerial agriculture hazard. Research AR‑2011‑028

Australian Government, Australian Transport Safety Bureau, 2006, Wire-strike accidents in general aviation: Data analysis 1994 to 2004 (Re-released September). Research and Analysis Report – B2005/0055

Gibb, R., Scharff, L. and Gray, R., 2010. Aviation Visual Perception: Research, Misperception and Mishaps (Ashgate studies in human factors for flight operations). Ashgate Publishing Group.

Szczecinski, Dr G. Cable, (date unknown), Aviation Medicine for Aircrew. Royal Australian Air Force Institute of Aviation Medicine.

Veillette, P., 2015. Wire wary: what you don't see can kill, and does. Business and commercial aviation.

Submissions

Under Part 4, Division 2 (Investigation Reports), Section 26 of the Transport Safety Investigation Act 2003 (the Act), the ATSB may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. Section 26 (1) (a) of the Act allows a person receiving a draft report to make submissions to the ATSB about the draft report.

A draft of this report was provided to the owner of the helicopter, the property owner, the helicopter loader and the Civil Aviation Safety Authority. Submissions from those parties were reviewed and, where considered appropriate, the text of the report was amended accordingly.

The occurrence

History of the flight

At about 1600 Eastern Standard Time^[1] on 24 March 2016, the pilot of Bell Helicopter Company 206B JetRanger, registered VH-WHU (WHU), landed at a property 5 km south‑west of Carmila, Queensland in preparation for aerial application agricultural spraying operations. The pilot met the property owner and together they reviewed the proposed operation. This included identifying significant features such as powerlines and property boundaries. A diagram was provided to assist the review.

The pilot and property owner then conducted a 15-minute aerial survey of the area in WHU to locate the features that were previously identified on the diagram. On completion of that flight, the pilot landed, secured the helicopter and retired for the night.

The pilot, property owner and loader^[2] for the operation met at the property at about 0545 the next morning. However, local fog delayed the commencement of the application until about 0700. During the intervening period, the helicopter’s hopper was filled with chemicals, the helicopter refuelled and its windows cleaned.

The spraying operations commenced at about 0700 and continued for a total of about 3.5 hours. During this time, the pilot landed and replenished the helicopter with fuel and chemicals 10 times, and was twice observed to leave the helicopter and ‘stretch their legs’. On one occasion, at about 0800, the property owner accompanied the pilot to clarify a section of the property to be sprayed.

At about 1000, the pilot landed and discussed the changing wind conditions with the property owner and loader. It was reportedly agreed during this discussion that the increasing wind would ultimately affect the chemical distribution. The chemicals were again replenished and the pilot decided to suspend operations for the day once the payload on board the helicopter was depleted.

The pilot took off and was observed flying at various locations around the property. The property owner and loader presumed the pilot was conducting ‘clean-up runs’. Shortly prior to the wirestrike, the helicopter was observed flying in a north-north-easterly direction, to the east of and adjacent to the north-south powerline (Figure 1). This line was strung low between three wooden power poles that were located between two sugar cane fields, about 8 m above the ground.

Concerned about the proximity of the helicopter to the powerlines, the loader radioed the pilot and reminded him of their location. The pilot replied ‘powerlines sighted and marked’. The loader continued with the job at hand and the property owner observed the helicopter complete two clockwise circles before tracking to the west, over the north-south powerline. The pilot continued the application to the north and west of the powerlines before turning back towards the east.

At about 1028, the helicopter collided with the north-south powerline (Figure 1).

Initially, the property owner alerted the loader that he thought the pilot was ‘in trouble’. The owner later described the helicopter at that time as being in a nose-up position, ‘hanging’ and making a loud noise. The property owner reported being unsure if the noise was engine or rotor system‑derived. The helicopter then lurched forward and spun clockwise before the property owner lost sight of the helicopter amongst the sugar cane.

The subsequent impact with terrain was not observed by the property owner or loader. There was a post-impact, fuel-fed fire that, despite the efforts of the property owner and loader, could not be readily extinguished. Impact forces and the post-impact fire destroyed the helicopter. The pilot was fatally injured.

Figure 1: WHU’s flight path, as reported by witnesses

Source: State of Queensland (Department of Natural Resources and Mines), modified by the ATSB

Pilot information

It is likely the pilot’s flight logbook was on board the helicopter at the time of the accident and destroyed in the post-impact fire. The operator understood that the pilot had flown 2,870 hours on a number of different helicopter types. An extract of the pilot’s logbook supplied by the operator showed that as of 14 February 2016, the pilot recorded 2,807 flight hours. The extract also showed that the pilot:

• undertook ‘Agriculture Rating training’ on the second and third of August 2014 that included 3.7 flight hours of flight time
• underwent a 1-hour ‘Agriculture II flight test’ on 4 August 2014
• completed a 1-hour ‘Aerial Application rating proficiency check’ on 22 September 2015
• performed 3.7 flight hours Aerial Seeding application on 24 September 2015.

The ATSB understood from the operator that the pilot also flew WHU for 4 days preceding the accident including ferry flights and 2 days aerial application of about 110 hectares under the direct supervision of the operator.

It is possible that the pilot flew additional aerial application hours prior to the accident as there was a period of 42 days between the last log book entry and the accident. Given the available evidence, this could not be confirmed.

The pilot held a current Class 1 Civil Aviation Medical Certificate with the following restrictions when exercising the privileges of the pilot’s licence:

• distance vision correction was to be worn
• reading correction was to be available.

Three pairs of heat-damaged sight correction glasses were identified in the helicopter wreckage. The ATSB could not determine if these included the pilot’s distance correction glasses or whether the pilot was wearing distance correction glasses leading up to the wirestrike.

The ATSB considered the potential for pilot fatigue to have influenced the development of the accident. This included a review of the pilot’s 72-hour history prior to the flight that day. Based on the available information obtained from witnesses and the operator, there was insufficient evidence to assess whether fatigue was a factor.

Weather, terrain and sun position

There was no Bureau of Meteorology weather station in the vicinity of Carmila. The closest aviation weather information was available from Mackay Airport, Queensland, about 85 km to the north of Carmila. Daily automatic weather observations were available from St Lawrence, approximately 50 km to the south of Carmila.

The 0900 observation at St Lawrence on the day of the accident recorded the following data:

• temperature – 27.1˚C
• relative Humidity – 64 per cent
• cloud – Nil
• wind Direction and Speed – east-south-easterly at 9 km/hr^[3]
• mean Sea Level Air Pressure – 1017.9 hPa.

At 1030 that day, the azimuth^[4] of the sun was 48°32’20’’ and its altitude^[5] 56°05’30”. During the flight, the pilot was wearing an aviation helmet that was fitted with a retractable sun shield. If lowered over the eyes, the sun shield was designed to reduce glare. Although the position of the pilot’s sun shield preceding the wirestrike was unable to be determined, the position of the sun was such that the potential for it to have been a factor in the wirestrike was minimal.

Powerline and poles

The area being sprayed was divided by powerlines that consisted of three cables, each made from three steel wires twisted together (Figure 2). The powerline that was struck by WHU was strung north‑to‑south, rusted and supported by three power poles over a distance of about 386 m (Figure 1). The poles to the north and south were located between tall trees (Figure 3). The centre of these poles was estimated to be about 3–4 m higher than the surrounding cane fields and was situated in a north–south clear area that was used as an access road.

Given the approximate 8 m height of the centre pole, and the normal spraying height of the helicopter, there was the potential for the pole to have been masked by the trees and rising terrain to the east of the powerline. The powerlines were not marked with visibility devices, nor were they required to be by regulation.

Figure 2: Power cable consisting of three steel wires twisted together (note the rust-like discolouration)

Figure 3: Terrain in the vicinity of the powerline, showing the helicopter’s direction of travel and the powerline and associated poles. Note the power pole that has been pulled down as a result of the wirestrike (centre of the picture) and the tree-lined creek that tracks right to left (located towards the top of the figure)

Guidance to aerial application pilots

The difficulty associated with identifying electrical and other wires and cables during aerial application operations is an acknowledged occupational hazard in the aviation industry. The Aerial Application Association of Australia Ltd.^[6] stated in their 3rd edition of the Aerial Application Pilots Manual that:

The pilot usually locates the wires by observing the run of the poles, thus establishing a mental picture of the treatment area in plain view i.e. by looking down on it. However, the actual treatment is undertaken close to ground level, where horizontal views are used to establish relationships between obstacles – an entirely different situation. There is plenty of scope for misjudgment. There is also a limit to the amount of attention a pilot can divert from maintaining a precise flight path to any obstacles, they must also consider. Therefore, great care must be exercised in transferring from ‘plan view’ to ‘elevation view’. In addition, the background to the wires - trees, hills etc. - may be concealed by intervening obstacles or by being so far towards the periphery of the pilot’s visual field that they are not noticed. Thus, to state the obvious, wires are very hard to see and their height and distance is not easily determined.

Human performance at low-level

Visual cues during low-level visual flying

Flight at low-level is widely acknowledged to be a demanding task, particularly in terms of processing the associated visual information. A key influence on the risk of a wirestrike in that environment is the pilot’s visual acuity given the environmental conditions.

A number of variables affect a pilot’s ability at any one moment to see and avoid powerlines. In this regard, Gibb and others (2010) describe the difficulty in seeing objects with varying contrast backgrounds where:

…an object’s visibility is affected by differences in its luminance contrast and differences in texture between the object and its surroundings. In general, more luminous and/or texturally-different objects are easier to discern from their background.

Veillette (2015) examined powerline visibility, highlighting that:

The near invisibility of wires results from a number of factors in addition to their size. These include atmospheric conditions, cockpit ergonomics, viewing angle, sun position, visual illusions, pilot scanning abilities and visual acuity, flight deck workload, and the camouflaging effect of nearby vegetation, among others. Even the condition of the aircraft’s transparencies, whether pitted, deteriorated with age, or dirty from dust or bug strikes, will significantly affect the pilot’s ability to see wires [and] depending on the lighting situation and background, lines can be obvious or invisible, and change from moment to moment.

and that:

Older wires may be difficult to see because their colour often changes with age….A wire that is perfectly visible from one direction may be completely invisible from the opposite. The exact location of specific wires may change throughout the day because of fluctuating ambient temperatures, which may cause wires to sag or tighten. Sagging wires may also be blown by the wind.

Perception and reaction time

Szczecinski (date unknown) listed the following times taken to recognise and react to a hazard:

It takes a finite amount of time for an object to be detected, recognised, a decision made on an action, and then for that reaction to be initiated. Table 1 lists the expected times for these events to happen. It can take up to 5.5 seconds for the process to be completed.

Table 1. Perception and reaction time

Aircraft information

The Bell 206B is a single main and tail rotor-equipped helicopter that is powered by a gas turbine engine and has skid-type landing gear. WHU was fitted with chemical spray equipment and a wirestrike protection system.^[7]

Wreckage and impact information

The accident occurred in an area where the sugar cane was about 3 m high. The terrain was flat, but rising towards the east, which was the direction of flight leading up to the wirestrike. Trees lined a creek that spanned from the east to the west of the property.

The vertical stabiliser and tail rotor assembly fractured from the boom during the accident sequence and were found about 30 m from the main helicopter wreckage. Scrape marks and gouging identified along and around the tail rotor section was consistent with colliding with a wire.

The lower portion of the vertical stabiliser displayed uneven, high-energy impact damage. The composite structure was abraded, roughened and had separated from the vertical stabiliser assembly. This was consistent with one of the powerline cables ‘pulling through’ the stabiliser during the impact sequence. The outer portions of both tail rotor blades were fractured and gouged, also consistent with colliding with one of the power line cables before separating from the tail rotor assembly (Figure 4). The liberated outer portions of the tail rotor blades were not recovered.

The helicopter’s structure, including the fuselage and cabin, was significantly compromised from the collision with terrain and post-impact fire. However, despite that damage, continuity of the flight control system was established.

An internal examination of the engine and gearbox confirmed continuity of the power and compressor sections of the engine and the drive to the gearbox. Each was likely capable of normal operation prior to the collision.

Evidence of the transmission of engine power from the gearbox to the main and tail rotors was identified. Fracture of the main rotor pitch links and torque twisting and fracture of the tail rotor drive shaft were consistent with the engine driving the rotor system during the impact sequence.

In summary, the damage to the helicopter was consistent with a wirestrike, followed by a collision with terrain and post-impact fire. No pre-existing defects, including cracks or fractures that may have contributed to the accident, were identified.

Figure 4: Separated tail rotor assembly, showing the liberation of the outer portion of both tail rotor blades, electrical arcing to the leading edge of one tail rotor blade (at inset) and the separated lower portion of the vertical stabilizer

Source: Queensland Police, modified by the ATSB

Research

The ATSB Avoidable accidents No.6 Experience won’t always save you, Pilot experience is not always a protection against an accident highlighted that:

• Experience alone can never compensate for high-risk activity.
• Sound decision-making and experience are not necessarily synonymous.
• Using pilot experience as mitigation for potential operational risks is inadvisable. If the risks are unacceptable for a qualified and competent pilot, there should be no reason for an experienced pilot to find it otherwise.
• In aviation, pilot’s need to attend to the three Cs- compliance, communication and complacency, and all the other human performance considerations. Experience cannot overcome the mental and physical limitations of humans.
• Experienced pilots who accept higher risks may not be as safe as a pilot with much less experience flying comfortably within the limits of his or her competency

In some accidents, the pilot’s vast experience was found to have perhaps even led to decisions that, in hindsight, were riskier than necessary.

__________

1. Eastern Standard Time (EST): Coordinated Universal Time (UTC) + 10 hours.
2. Loader: the term used to denote ground support personnel whose functions include assisting with mixing chemicals, and loading and dispatching the aircraft.
3. The wind direction and speed averaged over the 10 minutes prior to 0900.
4. Azimuth: the clockwise horizontal angle (in degrees, minutes and seconds) from true north to the sun.
5. Altitude: the vertical angle (in degrees, minutes and seconds) from an ideal horizon to the sun.
6. Prior to 2015 this organisation was known as Aerial Agricultural Association of Australia Ltd.
7. Equipment installed on aircraft to reduce the lethality of an impact with power or other cables.

Safety analysis

Background

On the day prior to the accident, the pilot flew to, and landed VH-WHU (WHU) at the property in preparation for the next day’s aerial application activity. The pilot and property owner used a map to review the area of operations, prominent landmarks and the electrical power distribution network in the area to be sprayed. The pilot and property owner then boarded WHU and surveyed the area from the air.

The pilot was appropriately qualified to command WHU and was endorsed to perform aerial application in the helicopter. However, in respect of the pilot’s aerial application qualification, the ATSB could not establish the pilot’s flight hours and current experience prior to the accident.

The operation that day

After an initial delay due to fog, the pilot flew about 3 hours aerial application in weather conditions that were described as ‘suitable’. This included the relatively light winds that were ideal for distributing the aerial chemicals. The pilot landed WHU about 10 times to replenish the chemicals and fuel. During two of these replenishments, the pilot left the helicopter to stretch their legs. The operator, loader and property owner reported that, before and during the operation, the pilot appeared to be in good health. No issues with the pilot or operation were reported.

About 30 minutes prior to the accident, the pilot landed and discussed the changing wind. It was decided that the next flight load would be the last for the day, as the wind was increasing.

The pilot was aware of the powerlines, having flown along and over them directly before the wirestrike. In addition, the loader alerted the pilot as to the proximity of the powerlines by radio. The pilot acknowledged this call, responding that the ‘powerlines [were] sighted and marked’.

The wirestrike

Despite the pilot’s awareness of the powerlines, as outlined by Veillette (2015), ‘being aware of a wire is still no guarantee of avoiding it’. That is, the pilot’s prior knowledge of the location of the powerlines did not assure their detection, and therefore avoidance, on each approach. Factors likely making visual detection of the wires difficult included that the:

• outer supporting power poles were obscured by trees as the pilot approached them, negating one of the visual cues often used by pilots to locate powerlines
• luminance of the power cables was reduced by their rust-like discolouration, reducing the likelihood of their detection by the pilot
• powerlines were not marked, and were not required to be marked, with visibility devices
• contrast in texture between the background and the powerline was decreased, including by a sugarcane field, rising terrain and a tree-lined creek. In combination, these features resulted in a camouflaging effect.

Those factors decreased the likelihood that the pilot would detect the north-south powerline in sufficient time to avoid the wirestrike. The ATSB could not quantify the extent to which the presence of visibility devices might have influenced the earlier detection of the powerline.

Evidence of scraping along the tail boom, the damage to the lower vertical stabiliser and the separation of the outer portion of the tail rotor blades indicated that WHU struck the powerline in a nose-up attitude. This would be consistent with the pilot taking action to avoid a wirestrike, but likely contributed to the wire passing underneath the lower component of the helicopter’s wirestrike protection system and striking the tail rotor and stabiliser assembly. The tail rotor and stabiliser assembly separated from the helicopter’s tail boom, resulting in a loss of directional control and a change in the helicopter’s centre of gravity. This would explain the property owner’s description of the helicopter lurching forward and spinning clockwise, contributing to the loss of control by the pilot.

Findings

From the evidence available, the following findings are made with respect to the wirestrike and collision with terrain that occurred about 5 km south-west of Carmila, Queensland on 25 March 2016 and involved Bell 206B helicopter, registered VH-WHU. They should not be read as apportioning blame or liability to any particular organisation or individual.

Contributing factors

During aerial application at low altitude, the helicopter collided with powerlines while in a nose up attitude, consistent with the pilot attempting to avoid the powerlines. The tail rotor and vertical stabiliser assembly separated leading to a loss of control and collision with terrain.

The masking of the outer two power poles by trees and the ‘camouflaging’ effect of the low contrast background cane fields, rising terrain and tree-lined creek reduced the available visual cues on the location of the powerline. This increased the pilot’s difficulty in maintaining visibility of the powerline.

Purpose of safety investigations & publishing information

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through:  identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2017 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.