What happened

On 24 January 2020, a Cessna 182Q was conducting a private flight operating under visual flight rules from Warwick, Queensland, to Dubbo, New South Wales. The pilot was the only occupant on board. Forecast weather in the area at the time was low cloud and thunderstorms.

During cruise at 4,500 ft AMSL, the aircraft encountered severe turbulence at a speed above the aircraft’s turbulence penetration speed. The pilot conducted a climb and levelled off at 6,500 ft in an attempt to avoid further turbulence.

The pilot reported that the aircraft then encountered a severe updraft, resulting in a climb and change of heading of approximately 180° with little to no control of the aircraft. He began a descent to remain out of cloud. The pilot then descended through cloud to 3,500 ft and tracked away from the area, clear of any further cloud and turbulence. While attempting to turn back onto heading, the aircraft was struck by a severe downdraft followed by an updraft, resulting in another heading reversal of approximately 180°.

During the post-flight inspection at Dubbo, it was identified that both wings near the wing strut were bent and warped with visible deformation.

Safety message

This occurrence provides a reminder that pilots need to be aware of their aircraft’s performance and turbulence penetration speed as turbulence can be unpredictable. Should an aircraft encounter severe turbulence, pilots are reminded to reduce the speed of the aircraft to safely navigate through the turbulence in order to avoid potential damage or loss of control.

Further information can be found in the ATSB research report, Staying safe against in-flight turbulence (AR-2008-034).

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

What happened

On 19 January 2020, a Boeing 737-800 departed Brisbane, Queensland for a commercial passenger flight to Melbourne, Victoria. There were 6 crew and 178 passengers on board.

Passing FL 250 on climb near Gold Coast Airport, Queensland, a cabin crew member advised the flight crew that a passenger alerted them to a panel hanging off the rear of the aircraft’s left wing. The flight crew requested that the cabin crew further investigate, and discontinued the climb and levelled off at FL 300.

The cabin crew subsequently showed pictures to the flight crew of the dislodged panel on the trailing edge flap area of the left wing. The crew then contacted air traffic control and requested a clearance to descend and return to Brisbane. The aircraft landed without incident and taxied to the gate.

Engineering inspection

Following the incident, the engineering inspection revealed that the inboard trailing edge flap on the left wing had delaminated (Figure 1). The engineers determined that the delamination was due to moisture ingress and excess heat from the engine exhaust.

Figure 1: Delaminated section on the aircraft’s left wing

Source: Operator’s engineering department

Figure 2: Diagram of trailing edge assembly

Source: Operator’s engineering department

Safety action

As a result of this incident, the manufacturer and operator have advised the ATSB that they are taking the following ongoing safety actions:

Manufacturer

• Boeing will be supplying a modified metallic assembly to be installed on aircraft.

Operator

• The operator conducted a fleet inspection of its aircraft aged 10 years old or older and found 7 other aircraft had delamination findings recorded. Due to delamination findings, the inspection program was expanded to flaps on aircraft 6 years old or older, to identify potential early defects on younger aircraft.
• A full damage analysis of the completed inspections and expanded program will support the determination of an effective threshold interval for introducing scheduled inspections via a new aircraft maintenance program task.
• Introduction of a modification program to replace the composite bonded assembly wedge with a new design metallic semi-monolithic assembly (Figure 3).

Figure 3: Diagram of new metallic semi-monolithic assembly for trailing edge flap

Source: Operator’s engineering department

Safety message

This incident provides a reminder that although flight crews conduct extensive pre-flight inspections, unexpected failures may still occur in flight. In this situation, the flight crew took all possible precautions by following the relevant procedures, conducting additional checks to assess the situation, providing clear communications to ATC and returning the aircraft to land.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

What happened

On 14 January 2020 at 1650 Eastern Daylight-saving Time, a Beech 58 Baron was conducting a community service flight from Inverell Airport, New South Wales to Maitland Airport, New South Wales, with a pilot and two passengers on board.

The aircraft overflew the airport and joined the circuit for runway 23. The pilot reported that there were no kangaroos observed during the overfly.

While flaring to land, a mob of kangaroos was sighted by the pilot to the left of the runway with one kangaroo subsequently entering the runway and contacting the aircraft’s nose landing gear. The nose gear collapsed, and the aircraft skidded along the runway for approximately 150 metres. While the aircraft continued down the runway, the pilot shut down the engines and selected fuel to off. The aircraft came to a stop and the pilot secured the aircraft before evacuating all occupants via the rear doors.

The pilot and passengers were uninjured, and the aircraft sustained damage to the nose landing gear, propellers and lower fuselage.

Figure 1: The aircraft post kangaroo strike

Source: NSW Police, digitally altered by the ATSB to remove the aircraft registration as occurrence briefs are de-identified.

Safety message

Airservices Australia’s En Route Supplement Australia (ERSA) entry for Maitland specifies that significant animal (kangaroo) hazard exists at this airport.

Kangaroos are among the ground-based animals that are most frequently struck by aircraft, as found in the ATSB report, Australian aviation wildlife strike statistics (AR-2018-035). Due to their size and unpredictable behaviour, they pose a serious safety risk for aircraft. Pilots should mitigate this risk as best they can by maintaining adequate situational awareness, particularly when operating at regional strips known for significant wildlife hazards.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

What happened

On 4 February 2020 at 0945 Eastern Daylight-saving Time, a Bombardier DHC-8 was conducting a precision runway monitor (PRM) approach^[1] to runway 16L at Sydney Airport, New South Wales. The scheduled passenger service comprised of a training captain as pilot monitoring, a first officer undergoing line training as the pilot flying, and a safety pilot. The aircraft was operating in visual meteorological conditions.

During the approach, with another aircraft also on approach to the parallel runway, the aircraft deviated from the runway centreline and the training captain instructed the first officer to re-establish the approach path. At this time, the safety pilot alerted the captain to select the additional PRM frequency to be monitored, as dual VHF is required during PRM operations.

ATC observed the DHC-8 to be within the no transgression zone (NTZ), which is a 610 m-wide safety buffer between the parallel approaches. The controller issued the aircraft with break-out instructions, in order to abort the approach. However, the aircraft continued the approach. It was later determined that the crew had inadvertently delayed selecting the additional PRM frequency and therefore did not hear the break-out instructions issued by ATC.

Safety message

This incident highlights the importance of effective crew resource management and adherence to standard operating procedures, particularly during phases of high workload when vulnerability to error is increased.

Further information on PRM operations can be found on the Airservices Australia website.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

__________

1. During periods of the day with peak arrival demand and inclement weather, capacity at Sydney Airport can be maintained with the use of PRM operations. A highly accurate surveillance system allows ATC to precisely monitor aircraft tracking on their approach paths and permit independent visual approaches.

What happened

On 3 January 2020, a Cessna 501 Citation was conducting a private flight with a single pilot and seven passengers from Merimbula, New South Wales to Moorabbin, Victoria. During the instrument approach to runway 35 at Moorabbin in low visibility conditions due to smoke, the pilot became visual with the runway environment at approximately 500 ft. The pilot reported that the aircraft was slightly high and fast compared to the normal landing profile but decided to continue with the landing.

The aircraft touched down past the normal landing point and at a higher than normal speed. Despite the application of maximum braking, the aircraft overran the end of the runway by approximately 20 metres. There were no injuries to the pilot or passengers. The aircraft sustained minor damage.

Pilot comments

In hindsight, my decision should have been to conduct a missed approach and proceed to my planned alternate where the weather was better.

Figure 1: Skid marks on the runway end leading to where the aircraft came to a stop.

Source: Supplied

Figure 2: Skid marks on the runway end into the grass.

Source: Supplied

Safety action

As a result of this occurrence, the pilot has advised the ATSB that they are taking the following safety actions:

• conducting a comprehensive debrief and review of the occurrence with their instructor
• undertaking further briefing and remedial training, concentrating on decision-making.

Safety message

This incident highlights the need for pilots to have a personal approach minimums checklist including clearly defined unstable approach criteria. If the approach does not meet these criteria or if there is any doubt, pilots should conduct a go-around.

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. One of the safety concerns is inflight decision making.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

What happened

On 16 December 2019, a Piper PA-32 departed from Groote Eylandt, Northern Territory for a chartered flight to Numbulwar, Northern Territory. There was one pilot and two passengers on board.

After landing in Numbulwar, the pilot conducted a post-flight inspection on the aircraft. During the inspection, he observed fuel leaking from the quick drain valve underneath the aircraft. He then conducted an inspection inside the aircraft to determine the reason for the fuel leak and found that the quick fuel drain lever had been moved into the open position.

The pilot moved the lever into the closed position and conducted a further inspection to ensure there was no more fuel leaking. It was determined that one of the passengers had inadvertently moved the quick fuel drain lever with their foot during the flight.

Safety message

This incident highlights the importance of comprehensive passenger safety briefings. A passenger briefing that includes an awareness of any controls within reach of passengers will help to ensure that these are not interfered with during the flight.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

What happened

On 13 November 2019, a Bell 214B helicopter was water bombing during fire control operations near Pechey, Queensland. At 1344 Eastern Standard Time, the helicopter approached the bushfire downwind and downhill from the north-west at about 60 knots, and made a descending right-hand turn back into wind over the fire.

The descent was continued towards the drop zone. The airspeed was further slowed and the height was reduced to about 150 feet above ground level (50 feet above treetop level). The pilot then released the load of water before departing the drop area into rising terrain. The pilot heard the low rotor RPM warning and had insufficient altitude and clearance from obstacles to recover the rotor RPM and continue flying. He was concerned that further actions required to recover the rotor RPM would result in the helicopter possibly striking trees or ending up in the actively burning fire.

In maintaining the climb to avoid rising ground, trees and fire, the rotor RPM appeared to decay further. As the helicopter cleared the trees, it began to descend, yawed to the right and the left-hand skid collided with the ground. The helicopter rolled onto its left side resulting in substantial damage. The pilot was able to turn off the fuel to stop the engine and exited the helicopter via the overhead window with minor injuries. Neither the g-force activated ELT beacon or flight tracking alarm were triggered.

The distance from the last water drop to the impact point was less than 100 metres and the recovered aircraft showed little evidence of damage from forward moment.

Figure 1: Aircraft prior to recovery – looking at reciprocal direction of approach. The final water drop occurred beyond the fuselage where the smoke is rising.

Source: Operator

Figure 2: Aircraft wreckage

Source: Operator

Operator’s investigation and comments

Based on the pilot’s account of the accident and assessment of the recovered aircraft, mechanical malfunctions were ruled out as a contributing factor. The operator determined that the accident was most likely the result of a loss of rotor RPM that the pilot was unable to recover, due to a downwind descending turn, low altitude for the water drop, and a departure into rising terrain. The pilot had to make a decision between putting the helicopter into tall trees and active bushfire or climbing over the trees to clear ground. In choosing the latter, the rotor RPM decayed further, and the helicopter contacted the ground.

The operator stated that the helicopter type is renowned for its ‘hot and high’ performance making it a very effective firefighting platform. Firefighting combines a number of factors which result in flying that is close to the performance limits of the aircraft – high gross weights, low airspeeds, low altitude, close quarters manoeuvring, high work rate environment and adverse weather conditions. In this case the combination of factors immediately leading up to the accident resulted in the helicopter operating outside its performance envelope without having enough space and height to recover.

Safety action

As a result of this occurrence, the aircraft operator has advised the ATSB that they are taking the following safety actions:

The operator has provided a briefing to all of their pilots on the circumstances and the outcome of this accident. The pilot involved in this accident will be involved in future training and checking to enable the recognition and avoidance of the circumstances that saw the limitations and flight envelope exceeded. This training will become part of the operator’s annual training for all pilots conducting fire control operations.

Safety message

Fire control flying operations can involve challenges and complexities that require crews to maintain a heightened awareness of their aircraft’s operating limits and the environmental conditions. Flying within operating limits can ensure pilots have a performance margin to react to unforeseen circumstances.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

What happened

On the morning of 16 November 2019, a BRM Aero Bristell departed Essendon Airport, Victoria to conduct an instructor-rating proficiency check flight. There was an authorised testing officer (ATO) and instructor on board.

During approach into Drouin, Victoria, the ATO directed the instructor to perform a practice forced landing onto the grass airstrip. The instructor reduced power to idle, adopted best glide speed for the aircraft and began the approach. During the approach, the instructor acknowledged that he would not make the selected touch down point. He applied power of about 100 RPM to assist in the approach. Upon the application of power, the ATO noticed that the aircraft contacted treetops and foliage. Further power was then applied to correct the flight path and to clear the obstacles.

The aircraft landed without further incident and was taxied to the parking area for inspection by the crew. There was no visible damage identified. The crew notified the training organisation’s on-duty instructor and subsequently conducted a return flight to Essendon.

Safety action

As a result of this occurrence, the aircraft training organisation has advised the ATSB that they are taking the following safety action:

A meeting was held with the organisation’s instructional staff to brief them of this occurrence and to advise them that if an incident of this nature should occur, an engineer must confirm the aircraft is safe for further flight.

Safety message

During training flights, testing officers and instructors need to be vigilant and prepared to discontinue a glide approach if it is established that a successful landing cannot be achieved. It is important to be aware of any obstacles or obstructions in the flight path and to ensure clearance is maintained at all times. In the event of contact between an aircraft and treetops or obstacles, such as in this occurrence, it is imperative that an engineer confirms the aircraft is safe for flight.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

What happened

On 8 November 2019, a Robinson R44 helicopter was conducting sling load operations about 10 NM north-east of Jabiru, Northern Territory. On the first lift of the day at approximately 1430 Central Standard Time, the pilot attached a load estimated to be about 120 kilograms to the helicopter by a 30-foot sling. In the prevailing windless conditions, the pilot lifted into a high hover, began to lift the load off the ground, and continued to climb until the load was clear of the surrounding trees. Once established in the hover, at approximately 80-100 feet AGL, the pilot observed all the engine gauges to be in the normal range and the helicopter appeared to be operating normally.

As the pilot commenced the translation into forward flight over a treed area, the rotor RPM began to decay and the low rotor RPM warning horn sounded. The pilot unsuccessfully attempted to regain rotor RPM by lowering the collective^[1] and increasing the throttle. In an attempt to alleviate the situation by reducing the weight on the helicopter, the pilot released the slung load. This action did not assist with the recovery of rotor RPM and the aircraft continued to descend into the trees before colliding with the ground.

Figure 1: Area of operations and wreckage

Source: Operator

Operator’s investigation

The operator has conducted an investigation into the circumstances surrounding this accident.

The investigation revealed that in the hot and humid operating conditions, a contributing factor to the accident was the pilot over-pitching during the sling load operation. The over-pitching was to such a degree that it made successful recovery in the circumstances unlikely. The operator’s investigation also stated the pilot’s decision to depart the pick-up location over a treed area when clearer areas were available also restricted the options available once the helicopter started to descend.

Over-pitching

The International Civil Aviation Organization (ICAO) manual of aircraft accident and incident investigation, chapter 15: Helicopter investigation, described over-pitching as a phenomena that happens when collective pitch is increased to a point where the main rotor blade angle of attack creates so much drag that all available engine power cannot maintain or restore normal operation rotor speed. At low rotor speed, the rotor blades bend upwards and drag increases. The high inflow angles and rotor drag quickly decay main rotor speed, which may decrease to the point where the main rotor blades stall.

Hover performance

Hover performance is essentially a product of engine power available and engine power required. The main factors affecting engine power required in a hover are helicopter weight, density of air and proximity to the ground (ground effect).

To maintain a steady high hover, lift a sling load or climb, the helicopter requires more main rotor thrust to act as lift, which in turn requires more engine power.

As air density decreases with an increase in altitude, temperature, and to a lesser degree humidity a normally aspirated engine produces less power. Additionally, if the same amount of rotor thrust is needed, the rotor blades need a higher angle of attack, which creates more drag and generates a requirement for more engine power.

When a helicopter is hovering within about one rotor diameter^[2] of the ground, the performance of the main rotor is affected by ground effect. A helicopter hovering in-ground-effect requires less engine power to hover than a helicopter hovering out-of-ground-effect.

Safety action

As a result of this occurrence, the operator has advised the ATSB that they are taking the following safety actions:

The operator will produce a report for all company pilots to fully explain the circumstances surrounding this accident to further educate and train pilots of the considerations when undertaking similar operations. To increase the safety of company operations, this further training will concentrate on decision-making, helicopter performance and weather effects, over pitching and using available terrain features when approaching and departing from unprepared landing sites.

Safety message

This accident serves as a reminder that when operating helicopters from unprepared landing sites, pilots should consider the approach and departure routes available in conjunction with operational constraints, weather (particularly wind), performance available and possible emergency recovery. Time spent considering and confirming the fundamental factors of decision-making, helicopter performance and limitations and the consideration of actions in an emergency may help prevent injury to crew and damage to, or loss of, an aircraft.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

__________

1. Collective: 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.
2. The Robinson R44 main rotor diameter is 33 feet.

What happened

On 15 October 2019 at 2100 Eastern Daylight-saving Time, an anchor handling tug supply vessel was engaged in anchor handling operations with an offshore drilling rig. The operation involved deploying one of the rig’s anchor cables onto the vessel’s deck and disconnecting it from the rig. The vessel utilised a ‘J-lock’^[1] to acquire and recover the chain. While in position approximately 45 m from the rig, the anchor handler believed they had J-locked onto the links of the anchor chain, close to where the cable transitions from chain to steel wire.

Once the anchor handler had locked onto the anchor chain,^[2] the rig paid out approximately 200 m of wire to allow the anchor handler to move to a safer spot to bring the chain onto the vessel’s deck. As the anchor handler began recovering the chain onto the deck (through a winching system), it became evident that the J-lock was not securely locked onto the anchor chain.

As the J-lock was deploying over the stern roller, the hook jumped from the anchor chain to the anchor wire. The abrupt change in weight and tension on the anchor handler’s winch wire resulted in the vessel being rapidly set stern-first towards the rig. Two of the vessel’s engines were set at maximum power ahead and the work wire was paid out, however neither of these actions could arrest the vessel’s sternway. At about 2118, the anchor handler made contact with the drilling rig. The anchor handler sustained structural damage to the rig leg.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

__________

1. A J-lock is a large hook in the shape of the letter ‘J’. The hook is used to snag and lock onto the chain links of an anchor cable.
2. To retrieve the anchor, the anchor handler deploys a j-lock on a wire that sweeps the ocean floor and acquires the anchor chain. Once securely j-locked, the anchor handler is able to begin reeling in the wire and anchor chain.