Key points: 

• A380 flight crew misheard ATC instruction, aircraft turned left instead of right
• Flight crew likely experiencing a high workload due conducting a missed approach after experiencing windshear
• In instructing a second aircraft on approach to land on a parallel runway to turn right, the second aircraft experienced a loss of separation with a third aircraft

The pilots of an Airbus A380 which turned left instead of right while conducting a missed approach to land at Sydney Airport, contrary to an air traffic control (ATC) instruction, were likely experiencing a high workload, an ATSB investigation found.

The Singapore Airlines A380 was operating a scheduled passenger service from Singapore to Sydney on 9 February 2020, with the flight crew—comprising the captain as pilot flying and the first officer as pilot not flying—having briefed before and during the flight on the forecast deteriorating weather at Sydney. Cleared for an ILS (instrument landing system) approach to Sydney Airport’s runway 16 right, the A380 encountered windershear while descending through about 1,000 feet. In response, the flight crew initiated a missed approach and advised air traffic control that they were ‘going around due to windshear’.

Air traffic control instructed the flight crew to turn right onto a heading of 270°. The first officer read back the heading, however, did not include the direction of the turn, and ATC did not correct the incomplete readback. The flight crew then commenced turning the aircraft left instead of right.

Air traffic control subsequently issued a safety alert to the A380 flight crew, advised them of a Bombardier Dash 8 (DHC-8) aircraft about 6 NM (11 km) on final for runway 16 left, and instructed them to turn right and climb immediately. Air traffic control then instructed the flight crew of the Dash 8 to make a right turn in order to maintain separation with the A380. This in turn resulted in a loss of separation between the Dash 8 and a Boeing 737, which was on approach to runway 16 right.

The minimum distance between the Dash 8 and 737 aircraft reduced to 2.6 NM (4.8 km) laterally and 1,300 feet (397 m) vertically.

“The ATSB found that the A380 flight crew were likely experiencing a high workload managing a high-energy aircraft state as a result of conducting the windshear recovery and missed approach,” said ATSB acting Director Transport Safety Kerri Hughes.

“This, in combination with an expectation that they would be turning left, contributed to the flight crew mishearing the ATC instruction to turn right.”

Ms Hughes said the incident highlights the importance of readbacks to provide assurance that air traffic control instructions are correctly understood.  

“The flight crew omitted the direction of the turn from their readback, which was not corrected by ATC. This was a missed opportunity to correct the misheard instruction,” she said.

“This incident highlights the importance of flight crew completing full readbacks, as well as controllers correcting any readback discrepancies immediately.”

In response to the incident, Singapore Airlines issued a notice to flight crew, highlighting strategies to manage high workload situations, as well as reiterating the importance of correct readbacks and acknowledgement from ATC.

Read the final report: Operational non-compliance involving Airbus A380, 9V-SKQ, near Sydney Airport, New South Wales, on 9 February 2020

Key points: 

• All crew members began feeling unwell on second flight of the day
• Pilot observed indications of elevated levels of CO on chemical spot detector
• Crew immediately opened windows and confirmed cabin heating was off, but their condition deteriorated
• The pilot alerted air traffic control and landed safely as soon as possible

The crew of a Cessna 172 conducting an aerial shark patrol experienced symptoms associated with carbon monoxide exposure, highlighting the dangers of this colourless and odourless gas found in piston-engine aircraft exhausts, an ATSB investigation notes.

The aircraft with a crew of three, comprising a pilot, communications officer and observer, had departed Adelaide’s Parafield Airport for a second aerial shark patrol at 1.30 pm on 22 December 2019.

While overhead Sellicks Beach, about two hours into the flight, the communications officer and then the pilot became sick. They initially dismissed their symptoms as being due to turbulence, but the pilot subsequently observed a localised discolouration on the aircraft’s disposable carbon monoxide chemical spot detector. The communications officer, in the front right seat, confirmed the discolouration and the crew confirmed they were all feeling light-headed.

The crew immediately opened the aircraft’s windows and confirmed the heating was off, however the pilot’s condition worsened and they reported losing periods of time, loss of feeling in their legs, chest pains, and a tingling sensation in their hands.

With support from air traffic control, the pilot was able to return the aircraft to, and land safely at Parafield Airport, despite experiencing increased light-headedness and ongoing confusion.

On landing, the crew were then taken to hospital for medical examinations. Blood test confirmed they had mildly elevated carboxyhaemoglobin levels.

“Despite having only mildly elevated carboxyhaemoglobin levels, the crew’s physical symptoms and cognitive effects likely resulted from exposure to elevated CO levels in the aircraft cabin,” said ATSB acting Director Transport Safety Kerri Hughes.

“Owners and operators of piston-engine aircraft are strongly encouraged to install active warning CO detectors to alert pilots to the presence of CO before it adversely affects their ability to control the aircraft or become incapacitated,” said Ms Hughes.

“Further, once they experience any smell or sensation of illness pilots should check their CO detector, ensure cabin heat is off, open all fresh air vents and windows, and make a prompt decision to land using all available resources for assistance – such as contacting air traffic control – to do this safely.”

In this incident, the CO source within the aircraft could not be established, Ms Hughes noted. There were no indications of a potential exhaust leak prior to the flight and the post-flight testing found no fault with the aircraft. However, the most likely source of CO was from the aircraft.  

For more information on the use of active warning CO detectors read the ATSB’s recent safety advisory notice: Are you protected from carbon monoxide poisoning?

Read the final report: Partial crew incapacitation involving Cessna 172, VH-YXZ, 44 km south of Adelaide Airport, South Australia, on 22 December 2019

Key points: 

• Aircraft was conducting a post-maintenance check flight
• Wreckage examination found no evidence of pre-existing defects with the aircraft’s flight controls or structure
• Fuel system components including the fuel flow indicator were recovered from the site for further examination

The ATSB will continue its examination of recovered components and the analysis of downloaded recorded data as part of its on-going investigation into the fatal accident involving a Dynaero MCR-01 light aircraft near Serpentine Airfield, south of Perth, on 28 December 2020.

The aircraft, with the pilot the sole occupant on-board, had departed Serpentine’s runway 09 at about 1438 local time to conduct a second post-maintenance check flight. Shortly after take-off, at about 300 feet above ground level, witnesses heard an audible change in the aircraft’s engine noise.

The preliminary report notes that the aircraft was then observed to make a slow turn to the left. A further change in engine noise was then heard before the left wing dropped and the aircraft was seen to enter a steep, nose-down rotating descent. The pilot was unable to recover the aircraft before it impacted the ground in relatively flat, open farmland about 200 metres east of the threshold of Serpentine’s runway 23.

The pilot sustained fatal injuries, and the aircraft was destroyed.

“To date, ATSB transport safety investigators have examined the accident site and aircraft wreckage, interviewed witnesses, and retrieved aircraft components for further examination. The retrieved components include a damaged GPS unit, aircraft instrumentation, the engine, propeller and fuel system components including the fuel flow indicator,” said ATSB Director Transport Safety Dr Mike Walker.

“No pre-impact defects were identified with the aircraft’s flight controls or structure,” Dr Walker noted.

“In addition, the aircraft’s fuel tank had ruptured, and a quantity of fuel had leaked into the soil.”

Dr Walker noted the preliminary report does not include any safety findings or analysis, which will be detailed in the investigation’s final report.

“As well as the analysis of data from the aircraft’s fuel flow meter and other electronic devices, and considering witness information, the ATSB’s investigation will examine the recovered aircraft components and review the aircraft’s maintenance history and flight characteristics,” he said.

A final report will be released at the conclusion of the investigation.

“However, should a critical safety issue be identified during the investigation, the ATSB will immediately notify relevant parties so appropriate and timely safety action can be taken,” Dr Walker noted.

Read the preliminary report: Partial power loss and collision with terrain involving Dynaero MCR-01 VLA, VH-SIP, near Serpentine Airfield, Western Australia, on 28 December 2020

Key points:

• Dash 8 surveillance aircraft’s engine failed on take off
• Power turbine shaft of the aircraft's right engine fractured due to fatigue cracking
• Corrosion pitting that exceeds repair limits on safety‑critical components should be a warning sign to manufacturers, maintainers, and operators

Corrosion pitting from prolonged low-altitude operations in a marine environment probably contributed to a Dash 8 surveillance aircraft’s engine failure on take-off, an Australian Transport Safety Bureau (ATSB) investigation has found.

The Surveillance Australia operated Bombardier DHC-8-315 aircraft with four crew on board was about to start its take-off roll from Darwin Airport on 11 November 2019. With the brakes on, power was applied to both engines. On reaching take-off power, and prior to brakes release, the crew heard a loud bang. The crew aborted the take-off and shut down the engine, while air traffic control advised the crew of smoke from the right engine.

After the aircraft had returned to the maintenance hangar, a runway inspection identified metal fragments behind the aircraft’s take-off position. An external inspection of the right engine revealed significant damage to the power turbine assembly.

“The ATSB’s investigation found that the power turbine shaft of the aircraft's right engine fractured due to fatigue cracking, resulting in secondary damage and engine failure,” said ATSB Director Transport Safety Stuart Macleod.

“The fatigue cracking initiated at corrosion pitting, which was probably associated with prolonged low‑altitude operation in a marine environment.”

The power turbine shaft originally installed in the engine was replaced during its first overhaul in 2011 due to excessive corrosion pitting. However, the maintenance organisation did not escalate the finding of corrosion to the engine manufacturer, Pratt & Whitney Canada (P&WC), possibly due to the informal reporting process at the time (formal guidance and criteria for reporting such findings was established in 2018).

The ATSB also identified that the power turbine shaft in P&WC PW100 series engines operating in certain marine environments is susceptible to corrosion pitting, which can grow undetected between scheduled inspections, increasing the risk of shaft fracture and engine failure.

“The corrosion-related fracture of the power turbine shaft of the aircraft’s engine in this occurrence highlights that corrosion pitting that exceeds repair limits on safety‑critical components should be a warning sign to manufacturers, maintainers, and operators that the existing maintenance strategy may not be effective,” said Mr Macleod.

“Additionally, manufacturers should provide guidance and criteria to maintenance organisations for assessing and reporting corrosion on safety‑critical components. This enables identification of whether the maintenance strategy is effective or if changes are required to reduce the risk of in‑service failures.”

P&WC has advised the ATSB it has commenced a review of historical overhaul experience of the power turbine shaft in an effort to identify which engines and operators are potentially exposed to an increased risk of shaft corrosion.

Additionally, P&WC has also proposed a range of safety actions to address the identified safety issue concerning the corrosion-related fracture of power turbine shafts in PW100 series engines that should complement its formalised reporting process. This includes considering a borescope inspection of the power turbine shaft between overhauls during hot section inspections with defined corrosion inspection criteria and investigating a method to remove contaminants from inside the shaft during service. Additional mitigating action for engines within the PW100 engine fleet that have completed hot section inspections, but are potentially exposed to the risk of power turbine shaft corrosion, is also being assessed. 

“While the proposed actions should address the safety issue, no timeline for their implementation was provided. As such, the ATSB has issued a safety recommendation to P&WC to support its proposed actions to avoid a similar shaft fracture from occurring,” said Mr Macleod.

Read the final report: Engine failure during take-off involving Bombardier Dash 8, VH-ZZE, at Darwin Airport, Northern Territory, on 11 November 2019

Key points:

• The investigation identified a safety issue relating to lack of post-training supervision by the helicopter operator
• Shortly after being trained in powerline stringing operations, for unknown reasons, the pilot modified the stringing methodology
• Experience alone will not always prevent a pilot from having an accident

An Australian Transport Safety Bureau (ATSB) investigation into an accident where a Squirrel helicopter struck a powerline pole identified that the operator’s procedures had no requirements to provide any post-training supervision for powerline operations, and that what supervision was provided was ineffective in identifying that the pilot was using a modified stringing method.

The AS350B3e Squirrel helicopter, registered VH-SZS and operated by Aeropower, was stringing powerlines from the Mount Gunson South substation to the Carrapateena mine site, a total distance of 51 kilometres, approximately 60 kilometres east of Woomera Airfield, South Australia on 20 March 2019.

While pulling the draw wire with a nose-high and rearward attitude, the helicopter’s main rotor blades struck the pole about 17 metres above the ground. The helicopter subsequently impacted the ground near the base of the pole.

Several ground crew from the stringing team extinguished a small post-impact fire and removed the pilot from the aircraft to a safe distance. A short time later emergency services and paramedics from the mine site attended the scene and confirmed that the pilot, who was the sole occupant, had received fatal injuries. The helicopter was destroyed.

Shortly after being trained in powerline stringing operations, for unknown reasons, the pilot modified the stringing methodology. In addition to placing the helicopter at low level in the vicinity of the powerline poles, the modified methodology also exacerbated the uptake of dust. This, in combination with the position of the sun and the rearward attitude of the helicopter, likely reduced the pilots’ visibility of the pole and their situational awareness of it.

“There were no requirements in the operator's procedures to provide any post-training supervision for powerline operations,” Director Transport Safety Stuart Macleod said.

“What supervision was provided was ineffective in identifying that a modified stringing method was being used by the pilot.”

In November 2020, the ATSB were advised that Aeropower had taken a number of proactive safety actions specifically relating to the supervision and review of newly authorised pilots in specialist tasks.

“These actions taken by Aeropower address the key concern of the investigation's identified Safety Issue, being the supervision of pilots recently trained or authorised in a new specialist task,” Mr Macleod said.

“The mandated extension of command under supervision time, the introduction of periodic consolidation flight checks, and the mandated extension of mentoring time are all expected help better prepare newly trained pilots for solo operations and provide them with additional defences to the hazards associated with specialist flight tasks.”

The investigation also highlighted that experience alone will not always prevent a pilot from having an accident. In this case, the pilot was a very experienced deputy chief pilot with nearly 6,500 flight hours.

Research published by the ATSB in 2012 as part of its Avoidable Accidents series titled Experience won't always save you, showed experience does not always provide a safeguard.

“Using pilot experience as mitigation for potential operational risks is inadvisable," Mr Macleod said.

“The ATSB has found that in some occurrences very experienced pilots were undertaking flying that involved much higher risk. And as a consequence, we found that in those circumstances their flying experience alone was unable to help them avoid an accident.”

Read the final report: Collision with terrain involving AS350, VH-SZS, 60 km east of Woomera, South Australia, on 20 March 2019

Key points:

• Flight operated under visual flight rules and required a transit over the McPherson Range
• Aircraft encountered reduced visibility and the pilot likely became spatially disorientated, resulting in a loss of control
• Weather-related decision making can be highly complex

The pilot of a Wittman Tailwind light aircraft that impacted a ridgeline in the Tooloom National Park near the NSW-Queensland border on 12 January 2020 likely became spatially disorientated after encountering poor weather, an ATSB investigation has found.

The aircraft, with the owner-pilot and a passenger on-board, was returning from a fly-in at Evans Head in northern New South Wales that had been curtailed due to poor forecast weather conditions. Their flight to Boonah in Queensland required a transit over the McPherson Range, which varies in altitude with several areas above 3,000 feet above sea level and some peaks above 4,000 feet.

The ATSB investigation into the accident established that the aircraft departed Evans Head shortly after 130 pm and tracked north towards Boonah via the Richmond River valley. About 17 minutes into the flight the pilot commenced a 180° turn overhead the township of Kyogle and diverted south back down the valley to Casino, landing there shortly after 2 pm.

That initial flight from Evans Head indicated that the pilot was attempting to cross the ranges via a route known as the ‘border loop’, which is commonly used by VFR (visual flight rules) pilots to transit the range.

On the ground in Casino, the pilot left a voicemail message for a friend in which they stated they could not get past Kyogle due to the weather, so they had landed at Casino.

Shortly before 3 pm, the aircraft took off from Casino and flew in a west-north-westerly direction, which indicated the pilot was attempting to cross the range via another common VFR route, which involved tracking via the Toonumbar Dam, then Killarney to Warwick.

At 310 pm, recorded data showed that the aircraft commenced a series of rapid descents and climbs, between 3,100 and 4,000 feet, followed by a left descending turn, before shortly afterwards impacting terrain in dense rainforest. The pilot and passenger were fatally injured and the aircraft was destroyed.

“The ATSB found that the pilot, who was operating under visual flight rules, departed Casino with a high risk of encountering forecast cloud,” said ATSB Director Transport Safety Stuart Macleod.

Data from the last four minutes of the flight showed the aircraft’s groundspeed speed varied between 109 and 175 knots, while the aircraft’s rate of climb and descent varied between +2,400 feet/min and -2,400 feet/min.

“En route to Boonah, the aircraft encountered reduced visibility and the pilot likely became spatially disorientated, resulting in a loss of control.”

The abrupt speed and altitude reversals and the operation of the aircraft over and near its speed limitations were indicative of a loss of control, the investigation notes.

A final data point showed the aircraft descending at 1,800 feet/min while travelling at a groundspeed of 172 knots and tracking towards high ground.

Spatial disorientation occurs when the brain receives conflicting or ambiguous information from the sensory systems, Mr Macleod noted. It is likely to happen in conditions in which visual cues are poor or absent, such as in adverse weather or at night.

“Once airborne, the pilot would have been in a position to assess the in-flight visibility and cloud and rain in the intended direction of travel. However, it is possible that continuing to fly towards an area of low cloud was influenced by the inherent challenges of assessing low visibility conditions,” said Mr Macleod.

“Weather-related decision making can be highly complex and therefore more prone to errors,” he stressed.

“Unfortunately, weather-related general aviation accidents remain one of the ATSB’s most significant causes for concern.”

A recent ATSB safety education campaing titled ‘Don’t push it, DON'T GO - know your limits before flight’ was developed to remind VFR pilots of the dangers of flying into IMC and to highlight the actions they can take to avoid a weather-related accident, Mr Macleod noted.

That campaign highlights three key messages: the importance of thorough pre-flight planning and having alternate plans, that pressing on and entering instrument metereological conditions (IMC) carries a significant risk of spatial disorientation, and the value of using a ‘personal minimums’ checklist to help manage flight risks.

“Pilots without a current instrument rating should always be prepared to amend and delay plans to fly due to poor or deteriorating weather conditions, and not to push on,” Mr Macleod stressed.

“In this case the pilot initially did make a sound decision to divert to Casino and turn back from the first attempt to cross the ranges, demonstrating an awareness of the risk posed by the weather and the need to maintain visual reference.”

The pilot’s subsequent decision to depart Casino can be interpreted as likely taking advantage of acceptable conditions there with the notion that the weather further inland may have allowed for VFR flight over the ranges, the investigation notes.

“The ATSB encourages VFR pilots to build a robust understanding of the risks of flying into IMC and just how rapidly spatial disorientation accidents can happen,” said Mr Macleod.

Findings from other ATSB investigations into accidents where VFR pilots entered IMC were published in the ATSB’s recently updated Accidents involving Visual Flight Rules pilots in Instrument Meteorological Conditions publication.

Read the final report: VFR into IMC and loss of control involving Wittman Tailwind, VH‑TWQ, Tooloom National Park, New South Wales on 12 January 2020.

Key points:

• Helicopter experienced an immediate power loss while operating at low-level due to an air line leak created by a loose union
• A range of factors exacerbating the occupants’ injuries
• Contracting agency did not actively manage or effectively supervise the culling operation

The Australian Transport Safety Bureau’s (ATSB) investigation into the collision with terrain of a Bell JetRanger helicopter during feral animal culling highlights the importance of independent inspections following maintenance and the effective management of risks for low-level aerial shooting operations.

The accident occurred in the Kakadu National Park, Northern Territory on the morning of 21 May 2019 when JetRanger VH-FHW, with a pilot, shooter and spotter on board, was tasked to cull a mob of feral horses. The helicopter was operated by Jayrow Helicopters under contract to the Director of National Parks (DNP), while the shooter and spotter were experienced Kakadu National Park rangers.

The helicopter was at a height of about 50 feet above the ground and over a lightly wooded area when its engine decelerated to idle, the pilot later reported. The spotter later recalled hearing the engine surge.

Ensurring the throttle was fully open (which it was), the pilot quickly diagnosed the situation as a genuine emergency and flew the helicopter towards a small clearing slightly to the left of the nose in their direction of travel. While managing the forward speed and height to reach the clearing, during the forced landing the right side of the helicopter impacted a tree then landed heavily in a level attitude. All three occupants were seriously injured, and the helicopter was destroyed.

The ATSB’s investigation determined that the engine power loss was due to a leak created by a loose union on an engine reference air line. During maintenance four days prior to installing a power turbine governor, the union, which was downstream of the work completed, had not been checked for tightness. An independent inspection following the installation of the governor was probably not conducted, and document verification processes did not detect that the independent inspection had not been recorded.

“This accident highlights that maintenance activities carry risk of error and therefore independent inspections are a vital risk control,” ATSB Director Transport Safety Dr Mike Walker said.

“Inspections must be designed and conducted in a way that will capture critical issues, and visual inspections will not always be enough.”

The investigation also found that the helicopter’s cabin was not well prepared for the subsequent collision with terrain, with a range of factors exacerbating the occupants’ injuries or increasing risk. For example, the DNP required shooters and spotters to wear helmets, however helmets were not provided or used on a routine basis.

Safety issues were also identified with the ambiguous wording of a Civil Aviation Safety Authority (CASA) instrument permitting the use of harnesses, and CASA’s renewal of aerial platform shooting approvals without recurrent emergency training.

“The ATSB found that the Director of National Parks did not actively manage the risk of the aerial culling task, or effectively supervise the operation,” Dr Walker said.

“This allowed for an increase in the number of crew, a change in helicopter type and change of helicopter operator, which had all progressed without requisite risk management, exposing the crew to avoidable harm.”

Following the accident, the helicopter operator ordered an immediate fleet-wide check of the security of all flexible and rigid reference air lines in its engines and took action to ensure all crew members were aware of the risk associated with using only a harness instead of a seat belt. Additionally, the approved maintenance organisation improved the delivery of human factors training for its engineers, contracting an external provider to deliver the course.

“The Civil Aviation Safety Authority has planned action to resolve the ambiguity associated with the instrument permitting harness use, and to require operators to ensure task specialists are trained in normal and emergency procedures,” Dr Walker said.

Following the accident, the DNP suspended its aerial culling activities and in December 2019 commenced an internal review of standards of practice relating to aerial culling and personal protective equipment. The DNP has reaffirmed its requirement for the use of helmets during any future culling activities and has also undertaken a specialist aviation safety review into its aerial culling operation and is conducting an ongoing review of its risk management policy and practice.

“This investigation highlights that any organisation that requires staff to engage in high-risk aviation activities should obtain professional advice on task design, actively manage risk, and provide appropriate equipment,” Dr Walker said.

Read the final report: Engine power loss and collision with terrain, Bell 206B3 helicopter, VH-FHW, 107 km south-west of Jabiru, Northern Territory, on 21 May 2019

Key points:

• Insulation blanket ingested into one of two outflow valves, affecting aircraft pressurisation modulation
• Crew donned oxygen masks and conducted an emergency descent, landing uneventfully
• Maintenance instructions did not reference the insulation blanket installation procedure

An insulation blanket likely not correctly installed during maintenance was partially ingested by an outflow valve in a Fokker 100 airliner’s pressurisation system, resulting in the crew donning oxygen masks and conducting an emergency descent.

The Fokker 100 airliner, operated by Qantas subsidiary Network Aviation Services, was in the cruise at 26,000 feet on a scheduled passenger service for QantasLink from Perth to Geraldton on 10 August 2020 when the flight crew received an excessive cabin altitude warning. In response they donned their oxygen masks and commenced an emergency descent, and manually deployed oxygen masks for the passengers.

The aircraft levelled off at 9,000 feet, where the flight crew advised the cabin crew and passengers that oxygen masks were no longer required. They opted to continue the flight to Geraldton, rather than returning to Perth to avoid a flight at low level through showers and possible turbulence, where the aircraft landed uneventfully.

An engineering inspection determined that an insulation blanket had migrated from its location and became wedged in one of the pressurisation system’s two air outflow valves, affecting the aircraft’s ability to maintain cabin pressure. The subsequent investigation determined that the insulation blanket had likely not been properly secured to the aircraft’s structure during recent heavy maintenance which included zonal inspections, allowing it to move in flight and block the outflow valve.

On the Fokker 100 aircraft, insulation blankets located in the same area as the outflow valves are subject to the varying rates of airflow required to modulate cabin pressure and, if not correctly secured, are free to move and dislodge.

“The ATSB’s investigation found that while the aircraft manufacturer's instructions detailed that during maintenance installation blankets could be removed 'as necessary', those instructions did not reference the insulation blanket installation procedure,” said ATSB acting Director Transport Safety Vik Chaudhri.

“This resulted in insulation blankets not being secured to the structure.”

In response to the incident and the ATSB’s investigation, Fokker Services has advised the ATSB that it is in the process of taking a number of steps to prevent a re-occurrence, including adding the insulation blanket removal and installation maintenance manual references to the relevant job instruction cards.

In addition, the maintenance organisation, Fokker Services Asia, issued a ‘Maintenance Notice’ highlighting the importance of securing the insulation blankets in accordance with the manufacturer’s instructions. This notice was also included as part of its maintenance inspection finalisation paperwork.

Separately, Network Aviation conducted a fleet-wide inspection of its Fokker 100 fleet which identified a number of aircraft with incorrectly installed insulation blankets.

The ATSB also contacted Virgin Australia and Alliance Airlines, which also operate Fokker 100 aircraft maintained by Fokker Services Asia, to advise them of this occurrence. Both operators conducted their own inspections for incorrectly-installed insulation blankets.

“This investigation highlights the importance of clear and consistent procedures across all aircraft maintenance documentation to avoid misinterpretation and error,” said Mr Chaudhri.

“Further, when removing a part or component, it is best practice to not assume it had been correctly installed previously. In all cases, the relevant maintenance documentation should be referred to, ensuring the part or component is being installed to the current specifications.”

Read the final report: Depressurisation involving a Fokker 100, VH-NHC, 167 km south-south-east of Geraldton Airport, Western Australia, on 10 August 2020

Key points:

• Engine flamed out shortly after departure from Geraldton
• Fuel flow regulator had seized due to internal gearing wear, despite being maintained within the recommended service life limits
• Crew decided to continue flight to Perth resulting in a longer exposure to one engine inoperative flight risks compared to returning to the nearest suitable airport (Geraldton). 

A Fokker 100 airliner’s engine flame-out during climb from Geraldton during a 9 July 2019 flight to Perth highlights the range of considerations for flight crews when managing power loss in complex aircraft.

The Virgin Australia Regional Airlines-operated Fokker 100 with two flight crew, two cabin crew and 24 passengers on board was climbing through 13,000 feet when the aircraft’s left Rolls-Royce Tay engine flamed out, which an ATSB investigation subsequently determined was due to the failure of the engine’s fuel flow regulator due to component wear.

After the flame-out the flight crew elected to maintain their airspeed of 250 knots and to continue to Perth. In addition, due to a desire not to ‘strain’ the right engine, the pilot flying elected not to increase thrust from climb to maximum continuous, and/or reduce the aircraft’s speed towards the recommended single-engine climb speed of 155–170 knots. Consequently, the crew adopted a cruise level about 6,500 ft below the maximum engine-out altitude.

“Following the engine failure, the crew’s decision to continue to Perth, where the aircraft landed without further incident, resulted in a longer exposure to one engine inoperative flight risks, compared to a diversion to the nearest suitable airport, which in this case was Geraldton,” said ATSB acting Director Transport Safety Kerri Hughes.

At the time of the engine failure, the aircraft was about 41 km south‑east of Geraldton.

The investigation report notes that the crew probably assessed that the likelihood of a second engine failure was remote, but may not have fully contemplated the operational risks associated with continued single-engine flight at the lower altitude of 14,000 feet. Consequently, opportunities were missed to further mitigate operational risk via repositioning the aircraft into controlled airspace, more direct tracking to Perth and the optimisation of their glide range.

“By electing not to increase thrust on the right engine or adopt the aircraft’s recommended single-engine climb speed reduced the available climb performance of the aircraft resulting in a lower cruise altitude than the maximum available,” said Ms Hughes

“This, coupled with the decision to continue to Perth on the original indirect track, increased the duration of flight and the time that the aircraft was outside the glide range of emergency airports and controlled airspace, in the unlikely event that the second engine failed.”

The investigation found the fuel flow regulator seized due to internal gearing wear, despite being maintained within the recommended service life limits of the Rolls-Royce Tay 650-15 engine management programme.

The ATSB also identified that the failure of the fuel flow regulator resulted in engine 1 thrust variation for about 45 seconds prior to the engine flameout. That went undetected by the crew due to the effects of automation, focused attention on other cockpit tasks, and the absence of any alert prior to the engine failure.

Following this incident and a review of the global failure rate specific to the fuel flow regulator unit utilised by the Virgin Australia Fokker 100 fleet, Rolls-Royce amended the applicable component management plan revising the recommended full-life maximum overhaul interval for the fuel flow regulator down from 16,000 to 10,000 hours.

“This incident highlights that the initial indications of component failures and malfunctions may be subtle. Automation can obscure significant changes in aircraft system status, including engine health,” said Ms Hughes.

“The incident also illustrates the numerous factors to be considered when managing the initial and subsequent aspects of power loss in a complex aircraft.”

Read the final report: Engine failure involving Fokker 100, VH-FWI, 41 km south-east of Geraldton Airport, Western Australia, on 9 July 2019

Key points:

• Displaced threshold in-place for runway works
• Airport safety officer's car headlights were directed at reflective witches’ hats which to the pilots appeared as a row of lights across the runway
• Pilots misidentified the aerodrome works limit line as the displaced runway threshold lights

Ambiguous temporary airport works lighting contributed to an aeromedical King Air aircraft’s tyre striking an unseen temporary runway end light when landing at Cairns Airport at night, a new ATSB investigation details.   

The Royal Flying Doctor Service (RFDS) Beechcraft King Air 200 aircraft with a pilot in command under instruction, a supervisory pilot, a flight nurse and two patients on-board, landed on Cairns Airport’s runway 15 shortly after midnight on 9 July 2020. Due to on-going night runway works, runway 15’s threshold was displaced.

During the approach, the flight crew sighted an airport safety officer’s car with its headlights directed at what appeared to be a row of lights across the runway, illuminating the displaced threshold. The aircraft passed above the row of lights and touched down beyond it. However, the aircraft had landed short of the actual displaced threshold and a tyre struck an unseen temporary runway end light.

“The ATSB found that the airport safety officer's car headlights were directed at reflective witches’ hats that marked the works limit line, which was in front of the displaced threshold,” noted ATSB Acting Director Transport Safety Kerri Hughes.

“To the flight crew, this appeared as a row of lights across the runway. As a result, the flight crew misidentified the aerodrome works limit line as the displaced runway threshold lights. The actual displaced threshold lights were also indistinguishable from the taxiway lights that remained illuminated during the approach. This resulted in a runway undershoot as the aircraft landed short of the displaced threshold.”

While the runway was closed at night for normal operations during the works, a portion of the runway was available to the RFDS with prior notice, with the runway 15 threshold temporarily displaced by 1,856 metres.

The flight crew were unaware that their aircraft had struck anything on landing with the broken temporary runway end light – which had been taped to be unidirectional to aircraft using the reciprocal runway 33 and was therefore not visible to flight crew when they landed on runway 15 – discovered later that morning by an airport safety officer. An inspection of the aircraft identified a scuff mark on the right main landing gear tyre.

“Aerodrome works can pose a hazard to aircraft, particularly where there are unusable portions of a runway and a displaced runway threshold,” noted Ms Hughes.

“Aerodrome works markings and lighting must be unambiguous and laid out in accordance with relevant standards, to minimise the likelihood of confusion for flight crew and the potential for a runway undershoot or excursion.”

The ATSB’s investigation found that works and airport safety officers did not ensure the aerodrome works lighting was arranged such that the location of the displaced threshold was unambiguous to the flight crew. In addition, Cairns Airport procedures for temporary runway works lighting and markings were inconsistent and did not ensure lighting was not confusing to pilots.

Following the incident Cairns Airport implemented a number of safety actions for the remaining runway works, including ensuring that vehicle headlights were not directed towards the active runway, and illuminating taxiway lights only after an aircraft had landed.

Read the final report: Runway undershoot involving Beechcraft B200, VH-FDO, at Cairns Airport, Queensland, on 9 July 2020