The investigation into the in-flight break-up of a Cessna 210 near Albany, Western Australia highlights the need for operators and industry associations to make information available to pilots and employees about support services for problematic substance use.

On the morning of 24 October 2017, the owner-pilot of VH-DBU was observed at Albany Airport preparing the aircraft for the flight. A witness reported seeing the aircraft with its wheels chocked and engine operating, and the pilot outside of the cockpit. No one else was observed at the controls.   

After refuelling, the aircraft took off on a private flight to Bunbury with the pilot as the sole occupant on board.

It appeared that the pilot undertook some local flying before departing the Albany area. When about 30 km to the north-west of Albany a number of witnesses reported hearing, and in some cases seeing, the aircraft fly overhead. Witnesses recalled hearing a distinctive noise described as a sharp bang, crack of a whip, gunshot, or thunder and lightning. The aircraft was then seen in a steep descent until it disappeared out of sight, with smoke appearing shortly after indicating a post-impact fire.

The wreckage of the Cessna was located later that day dispersed over a wide area in the Mount Lindesay National Park, with the pilot found to be deceased.

The investigation found, for reasons that could not be established, abnormal operation of the aircraft produced high levels of unusual aerodynamic loading that exceeded the strength of the right wing and initiated an in-flight break-up and impact with terrain.

…the risks associated with continuing to operate with problematic substance use and the benefits of accessing help and support far outweigh the risks of a self-referral…

No pre-existing aircraft structural deficiency or damage, which could have contributed to the in-flight break-up, was found during the investigation. Local weather at the time was generally calm and clear.  

A postmortem of the pilot carried out at the direction of the coroner found no evidence of significant underlying medical issues. However, an accredited forensic science laboratory toxicological examination found the presence of methylamphetamine in the pilot’s system. The ATSB found that it increased the risk of operational misjudgements or mishandling due to impairment and involuntary action or inaction due to incapacitation, but this did not necessarily contribute to the accident.          

The ATSB’s safety message from this investigation is for operators and industry associations to consider how they can make information available to pilots and employees about support services for problematic substance use.

A self-referral for problematic substance use may be perceived as a threat to a pilot’s ongoing employment in aviation. However, the risks of continuing to operate with problematic substance use and the benefits of accessing help and support far outweigh any perceived risk of a self-referral.

Information for pilots should highlight that the Civil Aviation Safety Authority’s aviation medical framework allows pilots in stable remission to return to work. Information should include the increasing availability of employer and independent peer support organisations.

Further, the ATSB encourages pilots concerned about alcohol and drug use to visit the Human Intervention Motivation Study(Opens in a new tab/window) (HIMS) website. A cornerstone of HIMS is the understanding that substance dependence is a treatable medical condition, and is modelled on well-established overseas programs that have assisted thousands of pilots return to work.

Read the final report: In-flight break-up involving Cessna 210B, VH-DBU, 30 km north-west of Albany, Western Australia, on 24 October 2017

A runway excursion involving a Boeing 737 at Darwin Airport on 6 December 2016 draws attention to the effectiveness of centreline lighting on wider than usual runways.

Landing on a wet runway at night, with visibility reduced by heavy rain, the Virgin Australia 737-800 touched down more than 20 m to the right of the runway centreline. The aircraft continued to the side of the runway, and its right landing gear ran just off the edge, destroying six runway lights along a 400 m path before returning to the runway.

There were no injuries and only minor damage to the aircraft.

The ATSB found that a relatively small increase in crosswind had occurred at a critical time a few seconds before touchdown, and the crew were not aware how far the aircraft had deviated.

The two rows of lights alongside runway 29 at Darwin are further apart than what a flight crew would normally encounter, due to the relatively wide runway. The ATSB found that, in the absence of centreline lighting, this characteristic affected the crew’s ability to detect and correct the aircraft’s deviation.

“A wide runway without centreline lighting, such as at Darwin, poses a particular challenge for aircraft making approaches in darkness and heavy rain,” said ATSB Executive Director Transport Safety Mr Nat Nagy.

“In these circumstances centreline lighting greatly helps flight crews align the aircraft with the runway.”

While studying past reports of runway side excursions in reduced visibility, ATSB investigators discovered that a disproportionate number of them occurred on wider runways.

In response to the ATSB investigation, both the aircraft operator and airport initiated a number of safety actions, including providing flight crews with information about the specific risks of approaches to Darwin Airport at night in conditions with reduced visibility.

“It is important for pilots and operators to be aware of any circumstances that are different to what they usually encounter and account for it in their planning so that they are more likely to avoid being ‘caught out’ at a critical time,” Mr Nagy said.

The International Civil Aviation Organization (ICAO) recommends, but does not mandate, the installation of centreline lighting on wider runways. Of the two runways wider than 50 m in Australia, Darwin’s runway is the only one without centerline lighting.

The ATSB previously recommended the installation of centreline lighting at Darwin Airport after a 2003 runway side excursion. Its concerns were renewed following a 2008 hard landing though no recommendation was issued.

Darwin Airport is a joint military and civilian facility – the Department of Defence owns much of the airport infrastructure, including the runways, while Darwin International Airport operates the civilian aspects of it. Both have advised the ATSB that the installation of centreline lighting will be considered during any future runway works.

While studying past reports of runway side excursions in reduced visibility, ATSB investigators discovered that a disproportionate number of them occurred on wider runways. None of the studied excursions occurred on runways that had centreline lighting.

As a result, the ATSB issued a safety recommendation to ICAO to review the runway lighting standards in light of the new evidence available. 

Read the final report: Runway excursion involving Boeing 737, VH-VUI, at Darwin Airport, Northern Territory, on 6 December 2016

An ATSB investigation into the collision with terrain involving a Bell 206 helicopter shows how rapidly emergency situations can develop.

The accident occurred 75 km north-east of Emerald Airport, Queensland, when the helicopter was conducting power line inspections. The pilot had positioned the helicopter in a hover 30 feet above the ground and 40 metres from a transmission tower so that it could be photographed by a crew member.

After a short period of hovering, the pilot heard a ‘very loud bang’ through the airframe, which was also felt through the controls. The helicopter began to shake violently and bounce vertically. The pilot also reported seeing tiny pieces of debris falling in front of the helicopter.

In response, the pilot immediately lowered the collective intending to land in a clear area below, however the helicopter did not respond to collective or cyclic control inputs. Instead, the helicopter began to pitch upward and drift backwards before yawing to the right. The yaw could not be controlled with the tail rotor pedals, so the pilot moved the throttle to the idle position.

Despite attempts to remain level during the landing, the left skid contacted the ground and the helicopter rolled over. The pilot and crewmember were uninjured.

While recognising that on this occasion the pilot had limited control authority, the safety message from this investigation is regular practice and briefings of emergency actions will increase the likelihood of a correct response during an emergency situation.

An examination of the helicopter identified that the mast, both pitch links, and the swashplate were fractured. The fractured components and trunnion bearings (connecting the pitch links to the rotor blades) were sent to Bell Helicopter’s Engineering Laboratories for detailed examination. Bell Helicopter concluded that all of the fractures, including that resulting in the mast collar separation, were a result of overstress.

There were no findings made during the inspection that identified the probable factors contributing to this occurrence.

This investigation highlights how rapidly an emergency situation can develop. While recognising that on this occasion the pilot had limited control authority, the safety message from this investigation is regular practice and briefings of emergency actions will increase the likelihood of a correct response during an emergency situation.

Read the final report: Collision with terrain involving Bell 206, VH-SDZ, 75 km north-east of Emerald Airport, Queensland, on 18 November 2017

An Australian Transport Safety Bureau (ATSB) investigation into a dual hydraulic failure involving a Boeing 757 aircraft highlights that non-mandatory service bulletins can still have an impact on an aircraft’s reliability.

Soon after departing Auckland International Airport on 5 February 2018, while passing through 6,000 ft, the aircraft’s left hydraulic system quantity warning message displayed. The crew actioned the Quick Reference Handbook (QRH) checklist and obtained clearance from air traffic control (ATC) to level out in a holding pattern north-west of the airport

Shortly after commencing the holding pattern, the crew received further warning messages regarding both the left and right hydraulic systems. Following the QRH checklists, the crew shut down both system, declared a PAN call to ATC requesting an immediate return to Auckland. The aircraft landed without incident.

The ATSB investigation identified that the dual hydraulic failure was the result of sequential failures in the hydraulic system. The initial failure was a ruptured left main landing gear flex hose, which resulted in the loss of the left hydraulic system pressure. Subsequently, the power transfer unit (PTU) pressure switch did not operate as intended, following depletion of the hydraulic fluid from the left system. This resulted in overheating and failure of the right hydraulic system.

Although some service bulletins are not deemed to be safety-critical, they can still have an impact on aircraft reliability.

The pressure switch was the subject of a 2010 non-mandatory service bulletin that, if implemented, would likely have prevented the failure of the right system.

The safety message from this investigation is that although some service bulletins are not deemed to be safety-critical, they can still have an impact on aircraft reliability. While operators are required to implement all airworthiness directives, the ATSB recommends that operators familiarise themselves with non-mandatory service bulletins and consider the potential impacts of implementation.

Following the occurrence, the operator conducted preventative maintenance on the aircraft, replacing all of the main landing gear flex hoses as well as updating the PTU pressure switch to confirm to the published service bulletin. In addition, the operator revised the aircraft maintenance plan to introduce improved inspections and a time-limited life on the flex hoses.

Boeing recommends that operators perform periodic inspection of hose assemblies, paying particular attention to the high-risk areas of the landing gear area, the engine/pylon area and the tail/empennage area.

Read the final report: Hydraulic system failure involving Boeing 757, VH-TCA, Auckland International Airport, New Zealand, on 5 February 2018

PTU pressure switch installed on VH-TCA

Recent practice of emergency procedures helped a pilot to conduct a successful forced landing of a scenic flight in remote and difficult terrain.

On 14 May 2018, a Gippsland Aeronautics GA-8 Airvan departed Bellburn Airstrip, Western Australia on a scenic charter flight with the pilot and seven passengers on board. About 12 minutes after departure, as the pilot commenced a planned climb, he felt the aircraft’s performance become a bit ‘sluggish’, with lower climb and fuel flow rates than expected.

Various checks and troubleshooting did not yield any improvement in performance, and engine power slowly started to decrease. The pilot determined that a forced landing was required, and advised the passengers, briefing them on the process for evacuating the aircraft after landing.

During the descent, at approximately 150 ft above ground level, the pilot secured the engine and turned off the aircraft’s electrical system. During the landing roll, the Airvan’s wings hit some small trees and the aircraft came to rest in a ditch, tearing off the nose landing gear. The pilot and three passengers sustained only minor injuries.

The pilot’s handling of the forced landing contributed positively to the survivability of this accident in difficult terrain.

The ATSB investigation found that the air intake pipe to engine cylinder number six had probably detached in flight, leading to the loss of engine performance. There was insufficient evidence to determine why the intake pipe detached from the engine.

The pilot advised the investigation that recent practice forced landings in the Airvan had helped him to feel more comfortable with the emergency. In particular, the recent practice gave him a good appreciation for the aircraft’s glide ratio, which helped when selecting a suitable landing site.

The ATSB’s safety message from this investigation is the value of frequent emergency procedures training. The pilot’s handling of the forced landing contributed positively to the survivability of this accident.

Although flight reviews are required every two years as a minimum, the ATSB reminds pilots and operators of the benefits of more frequent practice of emergency procedures.

Read the final report: Engine failure and forced landing involving Gippsland Aeronautics GA-8 Airvan, VH-BFL, 8.5 km north-north-west of Bellburn Airstrip, Western Australia, on 14 May 2018

On 23 October 2017, a Cessna 210 light aircraft with two pilots on board, one operating as pilot-in-command and the other as pilot-in-command-under-supervision, departed Darwin Airport for Elcho Island, 530 km to the east of Darwin.

Despite making track diversions to avoid severe thunderstorms, the aircraft entered an area of strong convective activity with rapidly developing rain cells. This resulted in the aircraft experiencing severe turbulence and possibly reduced visibility.

The aircraft entered an uncontrolled descent, with witnesses reporting seeing the aircraft descending rapidly in a relatively flat attitude with a section of each wing missing. A combination of airspeed, turbulence and control inputs probably led to excessive loading on the aircraft’s wings, which separated from the fuselage in-flight.

The aircraft subsequently collided with terrain, fatally injuring both pilots.

In many cases, deviations of 10 nautical miles may not be enough for an aircraft to remain safely clear of the turbulent and powerful forces associated with storms.

“There are several safety messages from this investigation including the recognition and avoidance of tropical weather conditions that present significant hazards to flight,” ATSB Executive Director Transport Safety Nat Nagy said.

“Particularly challenging is identifying an appropriate distance to keep from thunderstorms, which comes through experience in operating in the tropics. In many cases, deviations of 10 nautical miles may not be enough for an aircraft to remain safely clear of the turbulent and powerful forces associated with storms.”

The ATSB’s investigation found that the operator’s risk mitigation of pairing a supervisory pilot with a trainee did not adequately address the weather-related risks because neither pilot had experience flying in the build-up to the wet season.

“Smaller operators employing pilots with limited exposure to local conditions can better manage related risks by pairing new pilots with ones who are experienced in flying in the Top End,” Mr Nagy said.

“The ATSB also encourages pilots to use all available resources to avoid adverse weather, including forecasts and requesting air traffic control assistance. Awareness of the weather avoidance actions of other pilots in the area can also be useful.”

Further, there is considerable value in ongoing education and guidance for all pilots in recognising and responding to deteriorating weather conditions during flight.

Read the final report: In-flight breakup involving Cessna 210, VH-HWY, 22 km east of Darwin Airport, Northern Territory, on 23 October 2017

Airbus is proactively updating software on its A320 aircraft to ensure pilots receive alerts at an appropriate level of priority during periods of multiple alerts and high workload.

The update follows an ATSB investigation into an unreliable airspeed indication and stall warning involving a Virgin Australia Regional Airlines Airbus A320 near Perth Airport on 12 September 2015.

While passing through 8,500 ft, the aircraft’s autothrust and autopilot disconnected and multiple system alerts were generated. The captain took manual control of the aircraft and continued the climb to 20,000 ft, and levelled off to troubleshoot the issues and plan a return to Perth.

On approach to Perth Airport while aligning with the instrument landing system, the stall warning activated. The warning stopped after six seconds and the approach was continued for a successful landing.

The ATSB found the autothrust and autopilot disconnect was the result of erroneous airspeed indications during the take-off and climb due to blocked pitot tubes. The erroneous airspeeds were not detected by the pilots but had been detected by the aircraft’s systems, which had triggered the disconnect and generated multiple alerts including a ‘NAV ADR DISAGREE’ alert.

… it is important that alerts and procedures be designed to ensure that the pilots can correctly diagnose the source of the erroneous information…

This alert requires the pilots to crosscheck the three airspeed indications and assists them in determining if the source of the alert is an airspeed or angle of attack disagreement. However, limited space in the alert message area meant it was initially pushed off the screen for engine-related alerts programmed with a higher priority but in this case not requiring immediate action by the crew.  

The crew’s high workload meant the procedures for these alerts initially were not actioned and they were unable to address the ‘NAV ADR DISAGREE’ alert for about eight minutes, by which time the airspeed discrepancies had corrected themselves.  

The ATSB found this sequencing of alert priorities and the alert’s associated procedure may have led the pilots to incorrectly identify the source of the alert as an angle of attack discrepancy, which the NAV ADR DISAGREE procedure advised had a risk of triggering an undue stall warning.

Combined with the multiple system alerts, which to the flight crew appeared to be unrelated, the flight crew thought the stall warning that activated during the approach was spurious and as such did not apply the stall recovery procedure. Stall warnings are triggered by angle of attack, not airspeed, and there were no indications that the angle of attack system was not functioning correctly.

ATSB Executive Director, Transport Safety, Mr Nat Nagy, said modern aircraft with multiple interacting systems can have many layers between the source information and the pilots. 

“The ATSB’s safety message from this investigation is where there is erroneous information from an information source, it is important that alerts and procedures be designed to ensure that the pilots can correctly diagnose the source of the erroneous information,” Mr Nagy said.

“Further, unless it is absolutely clear that it is erroneous, pilots should appropriately respond to stall warning alerts.”  

Airbus is currently in the process of updating the A320’s software so that the NAV ADR DISAGREE alert has a higher priority than the associated engine alerts. In the case of multiple alerts generated by unreliable airspeed, it will take precedence over the other associated alerts and be immediately visible to the pilots.

In addition, the ‘risk of undue stall warning’ message will be removed from the aircraft status related to the NAV ADR DISAGREE alert.

Read the final report: Unreliable airspeed indication and stall warning involving Airbus A320, VH‑FNP, near Perth, Western Australia, on 12 September 2015

Qantas has incorporated more complex stall warning recovery events in recurrent lesson plans for its Boeing 747 flight crews.

The improvements follow an ATSB investigation into an in-flight upset involving a Boeing 747-438 110 km south-east of Hong Kong International Airport on 7 April 2017.

While descending toward Hong Kong, air traffic control instructed the flight crew to hold at a waypoint. When entering the holding pattern, the aircraft’s aerodynamic stall warning stick shaker activated a number of times and the aircraft experienced multiple oscillations of pitch angle and vertical acceleration.

During the upset, some passengers and cabin crewmembers struck the cabin ceiling and furnishings, sustaining minor injuries.

The ATSB found that while planning for the descent, the flight crew overwrote the flight management computer-provided hold speed. After receiving a higher than expected hold level, the flight crew did not identify the need to re-evaluate the hold speed. This was likely because they were not aware of a need to do so, nor were they aware that there was a higher hold speed requirement above flight level 200.

Prior to entering the hold, the speed reduced below both the selected and minimum manoeuvring speeds. The crew did not identify the low speed as their focus was on other operational matters. The ATSB also found that due to a desire to remain within the holding pattern, and a concern regarding the pitch-up moment of a large engine power increase, the pilot flying attempted to arrest the rate of descent prior to completing the approach to stall actions.

In addition, the pilot monitoring did not identify and call out the incomplete actions. This led to further stall warning stick shaker activations and pilot induced oscillations, which resulted in minor injuries to four cabin crewmembers and two passengers.

The ATSB found the flight crew had limited training and guidance for stall warning recovery techniques at high altitude or with engine power above idle. Inconsistencies were also found in flight crew training of the awareness of the need to re-evaluate holding speed when there are changes in altitude, especially above flight level 200.

“Balancing competing attention or decision demands can interrupt trained flight crew responses leading to procedures not being completed in full, particularly so if flight crews are not receiving comprehensive and regular training in the application of these skills,” ATSB Executive Director Transport Safety Mr Nat Nagy said.

“Comprehensive theory and practical training can ensure that flight crews have a complete understanding of aircraft systems and maintain effective manual handling skills. This training should provide the knowledge to correctly configure the aircraft’s automatic flight systems and manual handling skills to respond adequately to in-flight upsets.”

Subsequent to the incident, Qantas provided retraining for all Boeing 747 flight crews in stall warning recovery scenarios and amended ground school lesson plans to ensure flight crews were adequately prepared to recover from stall warning activations at high altitudes or with engine power above idle.

Qantas also amended flight crew training manuals relating to hold speed selection and updated ground school lesson plans and information to ensure standardised training and holding pattern training.

In addition, Qantas proactively applied these measures across its Boeing 737 and 787 fleets.

Read the final report: In-flight upset involving Boeing 747-438, VH-OJU, 110 km south-east of Hong Kong Airport, on 7 April 2017

The derailment of an empty coal train despite temporary speed restrictions being in place highlights how track defects can deteriorate faster than expected, a new ATSB investigation notes.

The incident occurred at Denman, NSW, as an empty Pacific National coal train was travelling from Kooragang Coal Terminal at Newcastle to Wilpinjong Colliery, near Mudgee. The train consisted of three 90-class locomotives and 92 coal wagons, with a total mass of 2,099 tonnes (not including the locomotives), and a total length of 1,510 m. It had slowed to comply with a 20km/h temporary speed restriction (TSR) put in place a week earlier after a routine track inspection had identified track geometry defects, including a long twist defect

Despite the application of the 20km/h temporary speed restriction, the long twist defect deteriorated faster than anticipated to a point where the left-hand wheels of the lead bogie of the 64^th wagon behind the locomotives mounted the rail. The left hand wheels then tracked across the railhead for 10 m before dropping off the rail. The right hand wheels of the lead bogie also dropped off the rail into the four-foot (area between the rails). As the wheels ran in a derailed state, they impacted the track fastenings and the foot of the rail. A number of rail-welded joints, sleepers and fasteners were damaged by the derailed wheels, while the Up rail suffered a full cross-section break at a weld joint.

Track defects may deteriorate faster than expected.

The rail break also broke the track circuit, which triggered a signal failure.

All the wheels of the lead bogie ran in a derailed state for approximately 690 m before striking the steel road plate of a level crossing and re-railing.

The train crew were unaware of the incident until they were notified by a network controller after a signal electrician, sent to investigate the signal failure, advised of track damage at that location. The train stopped approximately 71 km away from the derailment site.

After the earlier routine hi-rail inspection had identified the track issues, repairs to the defects had been scheduled for the day after the incident occurred. While the temporary speed restrictions had been put in place, issues with drainage and existing formation defects may have caused the long twist defect to deteriorate more quickly than anticipated.

The ATSB’s safety message from this investigation is that track defects may deteriorate faster than expected. Factors that can contribute to rapid deterioration should be considered when developing maintenance responses.

Read the final report: Derailment of freight train WG713, Denman, New South Wales, on 19 January 2016