Turbulence during shallow approach results in collision with terrain.

Key points:

• Approach profile was lower than intended.
• Aircraft pitched up on encountering turbulence.
• Accident highlights the importance of aircraft adopting an approach profile that mitigates the effects of gusty or turbulent conditions.

Turbulence during a shallower than intended landing approach resulted in the pilot of a Cessna 172 aircraft electing to reduce power and land in a tree canopy about 50 metres short of the runway threshold, an ATSB report says.

On 22 March 2020, a Cessna 172 aircraft, registered VH-CCB, took-off for a local private flight from a private airfield at Canyonleigh, near Mittagong, in New South Wales, with the pilot and passenger on board. Soon after take-off the aircraft experienced turbulence and the pilot and passenger decided to terminate the flight. The aircraft turned for its final approach about 1 NM from the runway threshold and 400 ft above aerodrome level.  As it approached the runway over steep forested terrain, the pilot reported the approach profile was lower than intended and increased power. The aircraft then pitched-up on encountering turbulence.

After correcting the pitch attitude, the pilot saw the aircraft remained lower than expected and was not aligned with the runway. Uncertain whether the aircraft would be able to climb over the canopy to the runway the pilot reduced power and landed in the tree canopy. The aircraft came to a rest 50 metres short of the threshold and to the left of the runway. The pilot and passenger sustained serious injuries and the aircraft was substantially damaged.

The ATSB’s safety message featured in the report highlights the importance of adopting an approach profile that mitigates the effects of gusty or turbulent conditions. Also, pilots need to be go-around prepared and minded and go around if the approach becomes unstable.

For more information on for go-around preparedness read the Flight Safety Foundation Approach-and-landing Accident Reduction briefing note 6.1(Opens in a new tab/window) from the Approach-and-landing Accident Reduction (ALAR) Tool Kit.

Read the final report: Collision with terrain involving Cessna 172, VH-CBB, 31 km west of Mittagong, New South Wales, on 22 March 2020

ATSB releases APL England loss of containers investigation preliminary report.

An ATSB preliminary investigation report details that a container ship was rolling and pitching heavily in rough seas and high winds when it lost 50 containers overboard about 46 nautical miles south-east of Sydney on 24 May 2020.

The on-going investigation’s preliminary report sets out the incident’s sequence of events and outlines that as the APL England travelled down the east coast of Australia, the Bureau of Meteorology issued regular forecasts regarding a complex low-pressure system developing off the south-east of the country, with gale force wind warnings.

“By 0600 on Sunday 24 May, while maintaining a southerly course and a speed of about 7 knots, the ship was pitching and periodically rolling in high seas and gale force winds,” said ATSB Chief Commissioner Greg Hood.

“Shortly after, at 0610, the ship experienced a series of very heavy rolls, to about 25° either side of upright. On the bridge, with many items moving and falling to the deck and the crew holding on to maintain their footing, steering system and engine room alarms sounded, and then the main engine shut down due to a loss of oil pressure.”

The report details that the crew restarted the engine, by which time the ship had turned to port, beam on to the seas, while continuing to roll heavily. The ship slowly gathered speed, and was turned easterly and then southerly, into the weather, before the crew then decided to head north, with the weather.

“It was not until skies had lightened - sunrise was at 0647 - that the chief officer first noticed the fallen stacks of containers,” Mr Hood noted.

“It was later established that 50 containers had been lost overboard from both forward and aft bays. One container lost overboard contained hazardous goods in the form of dry powder fire extinguishers, while 23 containers were empty.  A further 63 containers were damaged but remained on board.”

The ship would recover to the Port of Brisbane, where ATSB transport safety investigators were able to board the vessel to survey the damaged container stacks, inspect the container lashing equipment, download the vessel data recorder and video recording system, and interview the crew.

“Generally, the ship’s lashing equipment appeared in good condition. However, many of the ship fittings including lashing eyes, lashing bridges and deck structures were found to be heavily corroded and wasted,” Mr Hood said.

In addition, ATSB examination of the container stowage arrangement showed that the use of ‘high cube’ (2.9m/9ft 6in high) as opposed to standard height (2.6m/8ft 6in) containers in the ship’s aft-most container bay, bay 62, affected the security of the stow above the container cell guides.  However, the loading computer’s lashing and forces checks did not show any conflicts for this arrangement.

Mr Hood noted that the preliminary report does not include any safety findings or analysis, which will be detailed in the final report.

“The on-going investigation will review and analyse several areas of interest including the ship’s container stow and lashing arrangement; the maintenance regimes for the ship’s deck and engine room; the ship’s service and inspection history; the ship’s stability condition; weather conditions and information provided to crew; and the actions of the ship’s crew,” 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,” Mr Hood concluded.

Read the preliminary report: Loss of containers overboard from APL England, 46 NM south-east of Sydney, New South Wales, on 24 May 2020

Collision with terrain following in-flight simulated engine failure.

Key points:

• Aircraft rolled to the right and impacted the ground after a simulated engine failure after take-off
• Exercise was conducted in a configuration in which the aircraft was unable to maintain altitude with one engine inoperative
• Pilot likely had skill decay from lack of recent flying, instructor had minimal experience in aircraft type and limited experience in multi-engine aircraft with retractable landing gear

A twin piston-engined Angel 44 utility aircraft was conducting a simulated engine failure, when, about 20 seconds after take-off from Mareeba Airport in far north Queensland, it rolled rapidly to the right and impacted the ground, fatally injuring the pilot and instructor.

An ATSB investigation into the 14 December 2019 accident details that the aircraft was being used for a flight review of the aircraft’s owner-pilot, who was seated in the left seat, with an instructor in the right seat.

Witnesses at Mareeba Airport observed the aircraft touch down on the runway, accelerate and take off again. After take-off, the aircraft climbed to about 100–150 feet above ground level before entering the right descending turn.

“The ATSB found that shortly after take-off, the flight instructor very likely conducted a simulated failure of the right engine on a warm, humid day at a high aerodrome elevation in a configuration in which the aircraft was unable to maintain altitude with one engine inoperative,” said ATSB Director Transport Safety Dr Stuart Godley.

“Power was not immediately restored to the right engine to discontinue the exercise and the pilots were unable to maintain altitude or heading, particularly with the aircraft banked towards the inoperative engine,” Dr Godley said.

“The pilots did not reduce power and land ahead, as required by the aircraft’s flight manual, resulting in a loss of directional control and the aircraft rolling to the right. The loss of control occurred at a height too low to recover and the aircraft impacted terrain in a cornfield 475 metres north of the runway.”

Neither the pilot nor the instructor had any recent experience in the aircraft, which had not been flown regularly for more than two years, the investigation notes.

In addition, the pilot had not flown for three years before the accident, which likely resulted in a decay of skills at managing tasks such as an engine failure after take-off, while the instructor had limited experience in multi-engine aeroplanes with retractable landing gear, and had only once before flown the Angel 44 aircraft, several years earlier.

As a consequence, the investigation notes that the instructor was likely unfamiliar with the time necessary for the landing gear and flaps to retract – approximately 14 seconds, significantly longer than other aircraft the instructor had flown – and the associated detrimental effect that extended flaps and landing gear had on the aircraft’s single-engine climb performance.

“In light twin-engine aeroplanes, loss of power on one engine shortly after take-off poses a high risk due to low height above ground, low airspeed and generally limited single-engine climb performance,” Dr Godley said.

“When conducting simulated engine failures, it is essential that pilots understand the risks and ensure effective controls are in place to prevent the simulation turning into a loss of control at low level, where recovery will probably not be possible.

“Attempting to continue flight with one engine inoperative in a multi-engine aeroplane when directional control cannot be maintained, carries a high risk of an accident and fatal injuries.”

Dr Godley said the ATSB assessed whether the accident occurred following a simulated or real engine failure, as witnesses reported hearing an engine ‘splutter’ sound.

However, no evidence of a complete power loss was found, with both engines producing power at the time of impact, and with the ‘splutter’ consistent with simulation of an engine failure by rapidly retarding the throttle.

Nonetheless, investigators established that two of the fuel injectors in the right engine showed evidence of partial blockage by corrosion particles. That would have resulted in the over-fuelling of the other injectors and the engine running overly rich, backfiring, and reducing the maximum power available.

In the two years the aircraft had not been flown, its engines had not been preserved in accordance with the manufacturer’s procedures, the investigation notes.

“If an aircraft is not flown regularly, the airframe and engine/s need to be preserved in accordance with the manufacturer’s procedures,” Dr Godley noted.

Read the report: Loss of control and collision with terrain involving Angel Aircraft Corporation 44, VH-IAZ, near Mareeba Airport, Queensland, on 14 December 2019

Government agencies jointly support Airport Safety Week.

The Australian Transport Safety Bureau (ATSB), the Civil Aviation Safety Authority (CASA) and Airservices Australia are working together in support of Airport Safety Week 2020, which runs across 19–23 October.

A collaboration between the Australian Airports Association (AAA) and the NZ Airports Association (NZ Airports), Airport Safety Week allows the aviation safety regulator, the independent transport safety investigator, and the air navigation service provider to amplify several areas of safety to influence airport operators and users.

While supporting this year’s theme which centres on maintaining airport safety and wellness through the COVID-19 pandemic and human factors in airport safety, the three agencies will also be highlighting the use of stop bars, runway incursion incidents, the importance of carrying out effective FOD inspections, and developing an effective Safety Management System (SMS).

In August this year, CASA made changes to the aerodrome rules to align them with international standards and expanded on the requirements of safety management systems. These changes mean some aerodromes will need to develop their first SMS and many existing aerodromes will need to review their SMS. CASA is sure the information provided throughout the week provide aerodromes with more information on how to create a SMS that meets the requirements of the aerodrome operation and regulations.

Last year the ATSB produced a publication to provide airport and aerodrome operators with advice on what to do should an accident occur, while providing a thorough understanding of the investigation process to help minimise disruption to airport operations.

Airport Safety Week 2020 is another opportunity to remind airport operators of three key responsibilities in the event of an aviation accident: respond, report and preserve. That is to respond with their aerodrome emergency plan, report the accident to the ATSB, and along with emergency services preserve the accident site. The booklet, titled Information and guidelines for aerodrome operators, can be found on the ATSB’s website.

Airservices Australia is using Airport Safety Week 2020 to highlight the criticality of Aerodrome Emergency Plans and the collaborative role Airservices emergency management staff can perform in reviewing and supporting improvements in this important area.

Many aerodromes across Australia have already benefitted from Airservices input and airport operators are being reminded that regardless of the size of the facility, Airservices expert safety advice is applicable to minimise the risk of safety occurrences in the aviation sector.

More information about Airport Safety Week can be found on the AAA’s website.(Opens in a new tab/window) 

Stop bars are now in use at five capital city airports around Australia.

The Australian Transport Safety Bureau (ATSB) and Airservices Australia are reminding all pilots and operators this Airport Safety Week to be aware that stop bar lights at runway intersections are now in operation at five capital city airports around Australia, and not to cross a lit stop bar at any time.

Stop bar lights are red when illuminated and are embedded across the taxiway at all runway holding points and intersections. Stop bars are controlled by Airservices Australia air traffic controllers during operational tower hours as an added safety measure to prevent an aircraft or authorised vehicle unintentionally entering or crossing an active runway.

Following the recent publishing of the final report into a runway incursion and subsequent rejected take-off event at Perth Airport on 28 April 2018, the ATSB’s investigation highlights the need for all pilots, no matter their experience or what aircraft they fly, to always observe for, and comply with the stop bar directions.  

After landing, the pilot of a Boeing 737-800 crossed a lit stop bar and entered the active crossing runway where another 737 had commenced its take-off. Airservices Aerodrome Controller in Perth Tower alerted the departing aircraft to the runway incursion and instructed the 737 to stop. Both aircraft stopped safely and there was no collision.

ATSB Chief Commissioner Greg Hood said that in the past five years (1 September 2015 to 1 September 2020) 100 runway incursions involving stop bars at Melbourne, Sydney, Perth Brisbane and Canberra airports had been reported to the ATSB. Of these occurrences, 89 involved aircraft with the remaining 11 involved airside vehicles.

“Fortunately, none of these runway incursions have resulted in any accidents,” Chief Commissioner Hood said. “All of these occurrences have involved airliners, general aviation aircraft and authorised airport vehicles at different times of the day and night, and at different holding points, so there has been no identifiable commonality.”

Airservices Chief Air Traffic Controller Glen Lang reminds all pilots and authorised airside drivers that they must not cross a runway holding point until the stop bar has been extinguished and they have received verbal clearance from air traffic control.

“If you have a clearance to enter the runway but the stop bars are still lit, please query this with air traffic control before proceeding,” Mr Lang said. “I would encourage all operators and pilots to include checking the stop bar status as a requirement in their line up and crossing runway checks.”

Read the investigation report into the runway incursion involving Boeing 737, VH-XZM, resulting in a rejected take-off involving Boeing 737, VH-VZL, Perth Airport, Western Australia, on 28 April 2018

ATSB welcomes appointment of new Commissioner.

The Australian Transport Safety Bureau (ATSB) today welcomed the appointment of Ms Catherine Scott as a member of the ATSB Commission, effective from 8 September 2020.

Appointed by the Deputy Prime Minister and Minister for Infrastructure, Transport and Regional Development, the Hon Michael McCormack MP, Ms Scott brings to the ATSB Commission a wealth of experience in the rail industry, including expertise in governance, finance and risk management, and regulatory frameworks.

Ms Scott is a fellow of the Australian Institute of Company Directors and has held a range of board memberships including the Office of the National Rail Safety Regulator, National Heavy Vehicle Regulator and V/Line Passenger Pty Ltd.

The ATSB’s Chief Commissioner, Mr Greg Hood, welcomed the expertise and experience Ms Scott brings to the Commission.

“I have no doubt Ms Scott will make a significant contribution to the ATSB's work of improving transport safety in Australia,” Chief Commissioner Hood said.

“I look forward to working with Ms Scott as we position the ATSB to support and advance the national transport safety agenda.”

Chief Commissioner Hood also thanked the outgoing Commissioner, Ms Carolyn Walsh for her significant contribution to transport safety during her tenure as the ATSB’s longest-serving Commissioner commencing on 8 March 2010. The Executive and staff also expressed their thanks to Commissioner Walsh for her passion, determination and unwavering commitment towards serving the Bureau’s needs and best interests.

Weather, aircraft performance and operating procedures focus for on-going C-130 large air tanker investigation.

Weather and environmental influences, aircraft performance and handling, and operating policies and procedures are among the areas of ongoing focus as the Australian Transport Safety Bureau (ATSB) continues its investigation into the collision with terrain of a C-130 large air tanker.  

Three aircrew were fatally injured when the aircraft impacted rising terrain after conducting a fire retardant drop to protect property at Peak View, north of Cooma, NSW on 23 January 2020.

“The interim report does not contain findings nor identify safety issues, which will be contained in the final report. However, it does detail the extensive evidence gathered to date, which has helped ATSB investigators develop a detailed picture of this tragic accident’s sequence of events,” said ATSB Chief Commissioner Greg Hood.

“To-date, the ATSB has interviewed other pilots and key personnel from the aircraft operator, NSW Rural Fire Service personnel involved in aviation operations, witnesses, C-130 and other aerial firefighting pilots, and key personnel in overseas aerial firefighting operations.”

In addition, while the aircraft’s cockpit voice recorder was inoperative, the investigation team drew upon ADS-B transponder data (used for air traffic control and surveillance); data recorded by the aircraft’s SkyTrac tracking system (used for monitoring by the NSW Rural Fire Service); and video of the accident taken by firefighters on the ground, to develop an understanding of the aircraft’s flight path.

Analysis of the witness video confirmed that the aircraft initially established a positive rate of climb and was banking to the left following the retardant drop, the report details.

After climbing for about 10 seconds the aircraft was then observed to roll from a left bank to a slight right bank. A maximum height of about 330 feet above ground level was reached before the aircraft was observed descending. A further seven seconds later, the aircraft was observed at a very low height above the ground, in a left bank, before it collided with the ground. 

In the video the aircraft is intermittently obscured by smoke, however, it is unclear if the aircraft flew behind the smoke or entered smoke, Mr Hood noted.

The report also notes that at the time of the retardant drop, the aircraft’s recorded ground speed (determined from ADS-B and SkyTrac data) was 144 knots, while prior to the impact, the groundspeed had increased slightly to a maximum of 151 knots.

Mr Hood said the ATSB’s examination of the accident site and recovered wreckage established no evidence of structural failure or pre-existing damage to the aircraft.

“All major sections of the aircraft’s structure were identified. No pre-existing airframe issues were identified, and there was no evidence of an in‑flight break-up or pre-impact structural damage,” Mr Hood said.

“All four engines and 16 propeller blades were located on-site, and a subsequent teardown inspection of the engines indicated they were rotating at impact.”

Due to the extent of damage, the elevator, aileron and rudder trim settings could not be established. However, on-site measurements of the flap screw jacks indicated the flaps were set at 50 per cent at impact, consistent with the expected setting following a retardant drop.

The aircraft was originally tasked to conduct retardant drops at the Adaminaby fire ground. However, after conducting a number of circuits over the fire ground, the crew determined that conditions were too windy and smoky to conduct a drop. Instead, the Cooma Fire Control Centre re-tasked the C-130 to conduct a retardant drop to protect property at Peak View, about 58 km to the east of Adaminaby.

Following the accident, the ATSB received multiple witness reports of the weather conditions at Peak View.

“Witnesses all consistently reported very strong winds from the north-west,” Mr Hood said.

“One resident noted that, although the prevailing wind was from the north-west, the direction and strength at ground level were also being influenced by the local terrain.”

A private weather station, about 1.3 km from the accident site, had recorded winds from the west of 15-16 knots, with a peak gust from the north-west of 43 knots.

Mr Hood said a Bureau of Meteorology analysis of the weather conditions on the day of the accident indicated that a cold front was approaching the accident location, with hot and strong north to north-westerly winds ahead of the front.

“The Bureau of Meteorology considered the conditions on the day were favourable for mountain wave development, and satellite imagery of cloud formations confirmed their presence in the general area of the accident,” he said.

“However, from the data available they were unable to determine the severity of mountain wave activity.”

The interim report also notes that the flight crew were appropriately licenced and endorsed, held valid medical certificates, and that there no indications they were fatigued. However, there was insufficient information available to the ATSB about the crew members’ sleep and non-duty activities to estimate fatigue levels with confidence.

“The investigation is continuing. However, should a critical safety issue be identified during the course of the investigation, the ATSB will immediately notify relevant parties so appropriate and timely safety action can be taken,” Mr Hood said.

Read the interim report: Collision with terrain involving Lockheed EC130Q, N134CG, 50 km north-east of Cooma-Snowy Mountains Airport (near Peak View), New South Wales, on 23 January 2020

Applications now open for the November intake of the Graduate Certificate in Transport Safety Investigation course.

The Australian Transport Safety Bureau (ATSB) and RMIT University recently established a strategic partnership to teach how to manage and lead accident investigations of aviation, rail and marine vehicles. Applications for the November intake of the Graduate Certificate in Transport Safety Investigation are now open.  

The ATSB and RMIT collaboration ensures the course is industry-relevant and work-integrated, and is a great career development opportunity for professionals to gain skills in transport safety investigation. RMIT has extensive expertise in multi-modal transport safety systems and experience in industry-focused education. The ATSB provides advice on the development of the program structure and the course material, and a significant number of topics are delivered by ATSB subject matter experts with in-depth industry experience.

“The Graduate Certificate Transport Safety Investigation imparted expert knowledge from both the ATSB and RMIT that enabled me to adopt improved practices into my companies own investigation program,” a recent graduate of the course John Schembri said. “This in turn provided valuable tools to our investigation procedures, as well adding to the credibility of the investigation program.“

The Graduate Certificate in Transport Safety Investigation consists of four courses (or units of study) which run in intensive blocks, which means you can fit them around your professional obligations.

The courses covered are:

• Investigation Readiness: intensive offered 23 – 27 November 2020
• Human Factors for Investigators: intensive offered 30 November – 4 December 2020
• Accident Investigation Fundamentals: intensive offered 15 – 19 February 2021
• Analysis and Analytical Writing Techniques: intensive offered 22 – 26 February 2021

Due to the ongoing travel restrictions in Victoria, the first two courses in this program (i.e., OENG1200 and OENG1201) will be delivered online in a virtual classroom. The corresponding delivery dates for these courses will remain unchanged, with further updates to be posted on the program’s webpage, and timely communicated to students, conditioned to the evolution of the current COVID-19 situation for the remaining two courses in early 2021.

If you are interested in improving your transport safety investigation skills within your work and are looking for industry-relevant training, you can find out more on the RMIT website(Opens in a new tab/window), including how to apply(Opens in a new tab/window) directly for the 2020 November intake. 

ATSB farewells longest-serving Commissioner, Carolyn Walsh.

The Australian Transport Safety Bureau (ATSB) has today farewelled Carolyn Walsh from its Commission after more than a decade of helping to improve transport safety for all Australians.

The ATSB’s longest-serving Commissioner, Ms Walsh provided guidance and advice drawing upon her more than 30 years’ experience in policy development, regulation and safety management at Commonwealth and state government levels.

“I would sincerely like to thank and acknowledge Commissioner Walsh for her tremendous contribution to the ATSB in general, and more specifically the provision of her invaluable rail industry knowledge and experience to improve transport safety in that sector,” ATSB Chief Commissioner Greg Hood said.

“During her 10 year tenure, her wealth of knowledge and depth of experience has greatly contributed to several high profile investigations.”

Ms Walsh jointed the ATSB Commission on 8 March 2010, bringing with her 15 years’ of experience in the transport sector, where she served as the Executive Director of Strategy in the NSW Office of the Coordinator General of Rail, and as Chief Executive of the NSW Independent Transport Safety and Reliability Regulator.

“The Commission, the Executive and staff of the ATSB express our thanks to Commissioner Walsh for her passion, determination and unwavering commitment in guiding and supporting the Bureau,” Mr Hood said

“We wish her all the very best in her future endeavours and thank her for her exemplary contribution to improving transport safety in Australia.”

Ms Walsh continues in the role as Chair of the National Transport Commission, and as the acting Chair at the NSW Environmental Protection Agency.

A new member of the ATSB Commission is anticipated to be announced in the coming weeks.

ATSB releases Broome R44 helicopter in-flight breakup accident preliminary report.

The Australian Transport Safety Bureau’s investigation into the in-flight breakup of a Robinson R44 helicopter at Broome, Western Australia on 4 July 2020 is continuing.  

A preliminary report from the on-going investigation details that the helicopter, with a pilot and three passengers on board, had departed a yard in the Broome industrial suburb of Bilingurr for a private local scenic flight.

As the helicopter reached a height of about 55 feet, witnesses heard a bang, which one described as sounding similar to a metal bar striking a metal pole. Footage from a nearby CCTV camera showed that the R44’s aft tail cone bulkhead, empennage, tail rotor gearbox and tail rotor assembly all separated from the helicopter in about one second. The helicopter climbed to around 75 feet while rotating rapidly to the right, before rolling and impacting the ground on its right side, about 30 metres from the departure point.

The pilot, who owned the helicopter, and a passenger, both seated on the right side of the helicopter, were fatally injured, while the front left seat and rear left seat passengers were seriously injured. The helicopter was destroyed.

“ATSB preliminary reports detail factual information established in the investigation’s early evidence collection phase, and contain no analysis or findings, which will be detailed in the investigation’s final report,” ATSB Director Transport Safety Dr Mike Walker noted.

The preliminary report details that on 29 June the R44 was ferried from Bilingurr to Broome Airport, where it was fitted with a tracking system.

“That pilot reported feeling a vibration in the tail rotor pedals that felt like someone tapping the pilot’s feet with spoons. The sensation was noticeable yet not strong enough to cause significant alarm.”

Three days later the helicopter’s owner, accompanied by a passenger, returned the helicopter to Bilingurr, where on landing the owner also reported feeling vibrations in the pedals, and requested maintenance engineers inspect the helicopter.

Subsequently on 3 July, a maintenance engineer visually inspected the R44’s flex plate, empennage, gearbox, pitch links and tail rotor assembly, and found no defects. In addition, the maintenance engineer and an apprentice used electronic dynamic balancing equipment to measure the dynamic balance of the tail rotor, which was found to be within limits.

A maintenance pilot started the helicopter, and while ground running the R44 could not feel any vibration through the pedals. In addition, the maintenance engineer leant into the cabin and placed their hands on the pedals, and also could not feel any vibration.

Due to the confined nature of the yard, and concerns over securing the site, the maintenance pilot elected not to test fly the helicopter, and so the tail rotor system was not assessed under load. The maintenance pilot stated separately advising the pilot who originally detected the vibration and the owner that the engineers had not detected a vibration, and that the tail rotor was in balance. The maintenance pilot also stated that the owner was told that no changes were made to the balance weights, that the helicopter had not been flown, and that an instruction from the engineer to conduct a check flight was relayed.

The accident flight was conducted the following day, with the helicopter owner as the pilot.

“It is not clear whether the pilot experienced any vibrations through the pedals at the time of the accident flight,” Dr Walker said.

“Nevertheless, the ATSB urges any R44 pilot who experiences unusual vibrations through the tail rotor pedals to land as soon as possible and follow the advice in the pilot’s operating handbook.”

The R44 pilot’s operating handbook advises that a “change in the sound or vibration of the helicopter may indicate an impending failure of a critical component. If unusual sound or vibration begins in flight, make a safe landing and have the aircraft thoroughly inspected before flight is resumed”.

A number of major components from the R44 were recovered to the ATSB’s technical facilities in Canberra for further analysis, including the tail rotor assembly, gearbox, vertical fin and rear section of the tail cone.

“No definitive results from our examinations are available at this stage, and a non-destructive 3D X-ray of the tail rotor gearbox prior to its disassembly did not find evidence of internal damage,” Dr Walker said.

“The ATSB will continue to extensively examine and analyse the recovered components as it seeks to determine the contributing factors behind the in-flight break-up.”

As the investigation continues, the ATSB will examine a range of aspects.

“These include the on-going, detailed technical examination of the helicopter’s tail and tail rotor assembly; continued review of the accident helicopter’s construction, assembly, flight and maintenance history; and further analysis of the CCTV footage,” Dr Walker said.

The ATSB will also review policies and procedures for maintenance check flights, and examine related occurrences involving the R44.

“While the investigation is continuing, should a critical safety issue be identified at any time, the ATSB will immediately notify relevant parties so appropriate and timely safety action can be taken.”

Read the preliminary report: In-flight break-up, Robinson R44 Raven I, VH-NBY, 3 km north of Broome Airport, Western Australia on 4 July 2020