Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation.
What happened
While cruising at 1,000 ft south-southeast of Great Keppel Island, the pilot reduced the throttle to slow down the aircraft in preparation for landing. As the power lever was reduced, the engine had an uncommanded full power increase. After assessing the situation, and to reduce the possibility of the engine’s maximum permitted RPM being exceeded, the pilot commenced a climb to 9,500 ft and turned the aircraft back toward Hedlow where the runway length and surrounding area was more suitable for a glide approach. Once within gliding distance, the pilot shutdown the aircraft’s engine and a successful glide approach was conducted at Hedlow airfield (Figure 1).
Figure 1: Aircraft flight path
Source: Flightradar24, annotated by ATSB
Engineering inspection
The engineering inspection revealed that the throttle wire had snapped approximately 5mm before the swage end that connects to the throttle lever arm (Figure 2). The steel rod that the cable end is fitted to was resistant to rotating with the movement of the throttle arm. This caused the wire to bend slightly as the throttle was moved in and out of the full power position. Over time, this movement caused the wire to stiffen and fatigue, resulting in the break.
Figure 2: Broken throttle wire
Source: Pilot
Safety message
This incident highlights the importance of flight crews maintaining awareness of all system states and the benefits of sound decision-making. In this instance, the pilot was quick to identify and troubleshoot the engine malfunction, which allowed the pilot to select an appropriate response that increased the likelihood of a safe outcome.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report and allow for greater industry awareness of potential safety issues and possible safety actions.
A VLocity passenger train collided with closed level crossing gates beyond Ballarat Station after failing to stop;
The investigation found that the train’s sanding system was ineffective at improving wheel-rail adhesion, and that safety controls were ineffective in mitigating against a train arriving at Ballarat Station travelling at excessive speed;
The occurrence highlights the importance of risk controls to prevent collisions because of slippery rail conditions.
A Vlocity passenger train’s sanding system was ineffective in improving wheel-rail adhesion as the train approached Ballarat Station on the evening of 30 May 2020 after light rain and in windy conditions, a transport safety investigation details.
The three-car V/Line Vlocity train was operating a service from Melbourne to Ballarat and Wendouree when, unable to stop at Ballarat Station, the train collided with the Lydiard Street North level crossing gates, which were closed to rail traffic, according to the investigation by Victoria’s Chief Investigator, Transport Safety (who conducts rail investigation in Victoria on behalf of the Australian Transport Safety Bureau).
“Slippery rail conditions existed for at least the final 2.5 km of the approach to Ballarat Railway Station and probably the final 5 km,” said Chief Investigator, Transport Safety Mark Smallwood.
“Light rain was the primary environmental factor in the development of the slippery conditions, and the very low levels of adhesion at the contact between the train’s wheels and the rail head substantially reduced the train’s braking performance.”
The driver made initial brake applications approximately 5.1 km from Ballarat Station when the train was travelling at just over 160 km/h, and made a full service brake application about 2.6 km from the intended stopping point. However, the train did not decelerate sufficiently and could not be stopped, the report details.
The train passed through the station and collided with the level crossing gates at an estimated speed of between 93 and 97 km/h. After impacting the gates, the driver subsequently brought the train to a stand approximately 640 m beyond the station.
One of the two passengers on board required hospitalisation, and the train driver and conductor sustained minor injuries. The impact destroyed the pair of southern gates, damaged the front and side of the train, and resulted in gate debris being scattered into the surrounding area.
“The investigation found that the train’s sanding system, which is intended to improve adhesion in slippery conditions by applying sand to the rail head, was ineffective at improving braking performance,” said Mr Smallwood.
Reviewing the train’s data logger, investigators established that the train’s wheel slip/side protection (WSP) and sanding systems both automatically activated during the approach to Ballarat Station.
“Several factors potentially adversely influenced the performance of the sanders that evening, including their design configuration, vegetation contamination in one sander box, and the lack of sand in a second,” said Mr Smallwood.
“There were missed opportunities to identify weaknesses in the sander configuration, while maintenance of the sander units did not test for discharge flow rates, and train preparation processes did not ensure a required minimum amount of sand in the sand boxes.”
Mr Smallwood noted that since the incident V/Line has implemented a number of measures to improve sander performance, and has installed sanders on the intermediate cars of three-car VLocity diesel multiple unit sets.
The investigation also found that safety controls were ineffective in mitigating against a train arriving at Ballarat Railway Station travelling at excessive speed and being unable to stop before colliding with the crossing gates.
To enhance management of this risk, V/Line has introduced a number of interim measures including reducing the permitted train speed on the approaches to Ballarat Station from 160 to 80 km/h, and installing overspeed-triggered operation of the Lydiard Street North level crossing protection.
“This occurrence has highlighted the importance of rail operators having risk controls in place to prevent collisions because of slippery rail conditions,” Mr Smallwood said.
“Controls include effective train-borne equipment such as wheel slip/slide protection systems and sanders, and targeted risk controls at locations vulnerable to risks associated with train overrun.”
A sightseeing balloon with 9 passengers on board collided with the side of a tree after entering fog during the descent to locate a suitable landing area
The balloon came to rest on the side of the tree, damaging the lower part of the balloon envelope
To reduce the collision risk if a balloon enters an area of visibility less than that permitted by the visual flight rules, pilots should ensure that an immediate recovery is commenced
A sightseeing balloon with 9 passengers on board collided with the side of a tree after entering fog during the descent to locate a suitable landing area, an ATSB investigation report details.
The Floating Images Australia-operated Kavanagh E-240 balloon was conducting a scenic flight near Ipswich, Queensland on the morning of 8 October 2021, with a pilot and the 9 passengers on board.
About 55 minutes into the flight, to the south of the Amberley RAAF Base, the pilot commenced a descent to locate a suitable landing area, during which the balloon entered an area of localised fog where visibility reduced to 10 metres.
The pilot continued the descent into the fog until a tree was observed in the path of the balloon. The pilot attempted to avoid the tree by initiating a climb.
However, due to the 20-30 seconds required before the descent could be arrested and a climb commenced, there was insufficient time for the tree to be avoided.
The balloon came to rest on the side of the tree, damaging the lower part of the balloon envelope.
The pilot subsequently climbed the balloon off the tree and above the fog. The flight continued to an uneventful landing in a nearby paddock that was clear of fog, near the Ipswich suburb of Yamanto.
While there were no injuries, 19 of the balloon’s 480 sewn panels required either repair or replacement.
“The ATSB investigation found that, contrary to the visual flight rules visibility requirement, the pilot entered an area of reduced visibility in which the visibility was 10 metres,” noted ATSB Director Transport Safety Stuart Macleod.
“This did not allow sufficient time to complete an avoidance manoeuvre when an obstacle was observed, as a result the balloon collided with a tree and the balloon envelope was damaged.”
In some circumstances, balloons are permitted to fly in significantly lower visibility than other types of aircraft. While this is mainly due to their inherently low flight speed, it also considerably reduces the available time to see obstacles.
“As balloons can only manoeuvre vertically and significant time may be required to transition from a descent to a climb, they have limited capability to avoid obstacles,” Mr Macleod noted.
“Therefore, to reduce the collision risk if a balloon enters an area of visibility less than that permitted by the visual flight rules, pilots should ensure that an immediate recovery is commenced.”
A King Air departing Essendon for Albury yawed to the left during take-off roll;
ATSB found that the left engine power lever had migrated rearwards as the friction lock had not been sufficiently adjusted during the pre-flight checks;
King Air power lever friction locks require careful adjustment to prevent power lever migration, particularly during take-off.
The insufficient tightening of a friction lock during pre-flight checks resulted in a Beechcraft King Air’s left power lever migrating to idle during the take-off roll, an ATSB investigation report details.
The King Air B200C aircraft, operated by Pel-Air, was departing Essendon for Albury on the night of 19 August 2021 to conduct a medical retrieval flight with a pilot, paramedic and doctor on-board. During the take-off, the aircraft experienced a reduction in power on the left engine and an uncommanded yaw to the left.
The pilot, who had about 16,000 hours of aeronautical experience, of which 42 hours were on the King Air B200C, initially managed the situation as an engine power loss and focused on maintaining directional control. However, when troubleshooting, they identified that the left engine power lever had migrated rearwards to the idle position. In response, the pilot moved the power lever back to take‑off power and adjusted the friction lock to prevent further movement.
The flight continued to Albury without further incident.
“The King Air’s power lever friction locks require careful adjustment to prevent the power levers moving inadvertently, particularly during take-off,” said ATSB Director Transport Safety Dr Stuart Godley.
“This is a characteristic generally known among King Air operators and pilots.”
When interviewed by the ATSB, the incident pilot reported that they were new to the B200C and unaware that power lever migration could occur during take‑off.
Another pilot from the operator noted that, until a pilot experienced a power lever migration, it could be difficult to know how much to tighten the friction locks.
“The power lever friction locks fitted to the King Air require careful adjustment to prevent power lever migration during take-off,” said Dr Godley.
“Operators should ensure pre-flight checks provide opportunities to confirm friction lock settings before the take-off run, and ensure pilots have adequate knowledge of friction lock sensitivity to help prevent and recover from inadvertent power lever migration.”
Dr Godley said the ATSB has released a safety advisory notice to all operators and pilots of King Air aircraft advising of power lever migration and the need to be aware of the careful adjustment required for the power lever friction lock.
“This incident highlights the importance of having a detailed understanding of the characteristics that may be specific to an aircraft type,” he said.
“In the case of the King Air, the design of the power lever system means that the friction locks required careful adjustment to prevent power lever migration.”
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This interim report details factual information established in the investigation’s evidence collection phase and has been prepared to provide timely information to the industry and public. Interim reports contain no analysis or findings, which will be detailed in the investigation’s final report. The information contained in this interim report is released in accordance with section 25 of the Transport Safety Investigation Act 2003.
The occurrence
On the evening of 24 October 2022 a Link Airways SAAB 340, registered VH-VEQ operated an air transport flight from Canberra, Australian Capital Territory to Sydney, New South Wales.[1] The captain was acting as pilot flying, and the first officer as pilot monitoring.[2]
At 1944 local time, as the aircraft approached Sydney, air traffic control cleared the aircraft for the instrument landing system (ILS) approach to runway 34 left via the waypoint SOSIJ. This was the first ILS approach conducted in the aircraft on that day, with the captain acting as pilot flying.
Unknown to the crew, and prior to commencing the approach, a fault within the left (captain’s) display processor unit[3] resulted in the captain’s electronic attitude director indicator (EADI) erroneously presenting a constant ‘on glideslope’[4] indication regardless of the aircraft’s altitude relative to the glideslope and without an EADI glideslope failure indication. Audio from the cockpit voice recorder and flight crew interviews indicated that the first officer’s EADI also probably presented similar erroneous information intermittently and without a failure indication.[5] The EADI localiser[6] course deviation and standby attitude direction indications were not affected.
As the aircraft approached SOSIJ in cloud, at night and with the autopilot engaged, the crew commenced a 90° left turn to intercept the localiser (Figure 1). The aircraft subsequently intercepted the localiser at an altitude and distance from the runway that positioned it close to being on the glideslope for the runway 34 ILS approach. The crew continued the approach using the autopilot and observed that the aircraft did not commence descending as expected to maintain the glidepath. In response, the captain disconnected the autopilot and manually increased the descent rate to that expected for the approach.
Source: Recorded flight data and Google Earth, annotated by ATSB
When the aircraft was about 5 nm from the runway, the crew conducted an altitude and distance check which showed that the aircraft was close to the glideslope. As the aircraft descended below 1,373 ft above mean sea level (AMSL) at 1,920 feet per minute, and with the erroneous ‘on‑glideslope’ indication still present, the captain re‑engaged the autopilot. The autopilot maintained this descent rate, resulting in the aircraft deviating significantly below the glideslope.
As the aircraft descended below 1,000 ft AMSL, the crew recognised that the approach was unstable due to the flaps not being in the required position. At about the same time, the ground proximity warning system activated to alert the crew to the glideslope deviation and, in response, the crew commenced a missed approach.
Following the missed approach, the crew carried out a required navigation performance approach to the runway and landed without further incident.
Further investigation
To date, the ATSB has:
interviewed the flight crew
examined operational and maintenance records
undertaken analysis of flight and cockpit voice recorder data
obtained flight data analysis from the aircraft manufacturer
obtained detailed information on the failed display processor unit.
The ATSB is awaiting additional analysis from an external party and is unable to progress the investigation further until that analysis has been received. As a result, the investigation has been deferred. Once that analysis has been received, the ATSB will recommence the investigation.
A final report will be released at the conclusion of the investigation. 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.
Purpose of safety investigations
The objective of a safety investigation is to enhance transport safety. This is done through:
identifying safety issues and facilitating safety action to address those issues
providing information about occurrences and their associated safety factors to facilitate learning within the transport industry.
It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action.
Terminology
An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue.
Publishing information
Released in accordance with section 25 of the Transport Safety Investigation Act 2003
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[1] The flight was operated under Civil Aviation Safety Regulations Part 121 (Air transport operations - larger aeroplanes).
[2] Pilot Flying (PF) and Pilot Monitoring (PM): procedurally assigned roles with specifically assigned duties at specific stages of a flight. The PF does most of the flying, except in defined circumstances; such as planning for descent, approach and landing. The PM carries out support duties and monitors the PF’s actions and the aircraft’s flight path.
[3] The display processor unit receives data from the aircraft’s systems and generates the text, colours, and symbols for presentation on the electronic attitude director indicator.
[4] Glideslope: Electronic signals that provide vertical approach guidance on aircraft instrumentation.
[5] The flight data recorder captured the glideslope indication on the captain’s EADI but did not record those presented on the first officers EADI.
[6] Localiser: Electronic signals that provide lateral approach guidance on aircraft instrumentation.
Final report
Executive summary
What happened
On the evening of 24 October 2022, a Link Airways Saab 340, registered VH-VEQ, was being operated on an air transport flight from Canberra, Australian Capital Territory to Sydney, New South Wales. As the aircraft approached Sydney, in cloud and at night, with the autopilot engaged, air traffic control cleared the aircraft for the instrument landing system (ILS) approach to runway 34 left.
The aircraft intercepted the ILS localiser at an altitude and distance from the runway that positioned it close to being on the glideslope for the approach. However, as the approach continued, the crew observed that the aircraft did not commence descending as expected, with the cockpit instruments indicating that the aircraft remained on the glideslope. In response, the captain temporarily disengaged the autopilot and manually increased the descent rate. The approach continued until the ground proximity warning system generated a ‘glideslope’ alert. At about the same time, the crew assessed the approach as unstable and commenced a missed approach.
What the ATSB found
The ATSB found that, unknown to the crew and prior to commencing the approach, an unidentified instrumentation fault resulted in erroneous on‑slope indications being presented on the pilot’s instruments without any failure indication. Consequently, the autopilot did not descend the aircraft as expected, resulting in the crew initiating a manual descent. The crew subsequently re-engaged the autopilot as the aircraft descended at a rate exceeding that required for the approach.
The autopilot maintained the excessive descent rate rather than recapturing the glideslope. As the aircraft descended below about 1,000 ft above ground level, the ground proximity warning system activated due to the significant deviation below the glideslope.
What has been done as a result
Although maintenance action could not be linked to the incident, the operator developed and implemented several maintenance‑related safety actions following the occurrence. These included a standardised component reinstallation (re‑rack) procedure based upon aircraft manufacturer guidance. This procedure aimed to reduce faults possibly created during defect troubleshooting. The operator also issued an internal notice to maintenance personnel that provided guidance on the required items to be included in maintenance explanatory text.
Safety message
During this incident, the crew faced a complex scenario where, unknown to the crew, an instrumentation failure presented them with erroneous on-glideslope indications, without any failure indications, while conducting a precision approach at night and in cloud. The absence of any failure indications reduced the ability of the crew to identify the fault, which incorrectly showed the aircraft on the correct and expected approach path.
The incident highlights the importance of assessing all available indications and being ready to initiate a missed approach early should there be a significant exceedance from expected aircraft performance or instrument indications, such as the excessive descent rate during this occurrence.
The value of adherence to operational procedures to ensure safe aircraft operation is also underlined—upon recognising that the approach was unstable and in response to the glideslope alert, the crew correctly conducted a missed approach. The crew then identified the subsequent erroneous glideslope indications and completed a safe landing using a different approach type.
The investigation
Decisions regarding the scope of an investigation are based on many factors, including the level of safety benefit likely to be obtained from an investigation and the associated resources required. For this occurrence, a limited-scope investigation was conducted in order to produce a short investigation report, and allow for greater industry awareness of findings that affect safety and potential learning opportunities.
The occurrence
On the evening of 24 October 2022, a Link Airways Saab 340 registered VH-VEQ, was being operated on an air transport flight from Canberra, Australian Capital Territory to Sydney, New South Wales.[1] The captain was acting as pilot flying, and the first officer as pilot monitoring.[2]
The aircraft departed Canberra at 1910 local time. At 1944, as the aircraft approached Sydney in cloud and at night with the autopilot engaged, air traffic control cleared the aircraft for the instrument landing system (ILS) approach to runway 34 left via the waypoint SOSIJ.
As the aircraft tracked toward SOSIJ, the crew configured the aircraft’s instrumentation and navigation radios for the ILS approach. Unknown to the crew, an instrumentation fault resulted in erroneous glideslope indications (see the section titled Instrument landing system) being presented on the electronic attitude director indicators (EADIs) without any failure indication.
At 1946:11 the aircraft was 13.7 NM from the runway and descending through 5,357 ft above mean sea level (AMSL). Shortly after, the crew used the autopilot global positioning system navigation mode to commence a turn to intercept the localiser track and at 1947:19, the first officer announced that the EADI localiser course bar was active.
The aircraft continued descending and at 1947:58, as the aircraft tracked to intercept the localiser, the cockpit voice recorder captured the first officer asking, ‘What’s it doing with the glideslope?’ (Figure 1).
Figure 1: Flightpath of approach
Source: Recorded flight data and Google Earth, annotated by ATSB
As the descent continued, the autopilot switched automatically to localiser mode and captured the ILS localiser at an altitude and distance from the runway that positioned the aircraft close to being on the glideslope for the approach. The autopilot subsequently captured the glideslope and the crew continued the approach using the autopilot approach mode. The crew observed that the aircraft did not commence descending as expected to maintain the glidepath, despite the EADIs indicating that the aircraft remained on glideslope. The captain assessed that there was probably some lag in the glideslope indication and its input to the autopilot capturing of the glideslope. To progress the aircraft’s descent along the glideslope, the captain disengaged the autopilot and manually increased the descent rate.
The crew continued the approach and when 6 NM from the runway, as the aircraft descended past 2,205 ft AMSL at 1,759 feet per minute (ft/min) and with an indicated air speed of 184 kt, the captain requested a height and distance check. The first officer advised that they should be passing 1,930 ft AMSL and the captain commented that the glideslope indication was ‘way out’.
At 1949:39, the crew selected the landing gear down and 8 seconds later, when the aircraft was approaching 5 NM from the runway, the captain requested another height check. The first officer advised that at 5 NM, they should be passing 1,610 ft and the captain commented ‘It seems as though we’re coming back on’. As the aircraft approached within 5 NM from the runway, it was descending past 1,693 ft AMSL at 1,280 ft/min at a speed of 176 kt.
At 1949:58, the descent rate increased to 1,920 ft/min and 5 seconds later, the aircraft descended through the 3° approach profile at a speed of 171 kt. At about the same time, the crew re‑engaged the autopilot in the glideslope and localiser hold mode. The approach continued and the autopilot maintained the excessive descent rate and the aircraft descended significantly below the glideslope. At that time, the first officer observed that both the glideslope and the localiser indications were centred.
A few seconds later, at 1950:08, the first officer commented that their EADI glideslope indication had commenced moving and was ‘… going way off now’. At the same time, air traffic control cleared the aircraft to land.
The captain then called for the flaps to be extended, but the first officer did not complete the action as they were engaged in trying to resolve the conflicting glideslope indications. A second later, as the aircraft descended below 957 ft AMSL (about 380 ft below the glideslope – full-scale deflection), the ground proximity warning system generated a ‘glideslope’ alert (see the section titled Ground proximity warning system) (Figure 2) and 7 seconds later, the crew commenced a missed approach. At 19:50:36, 10 seconds after the missed approach was commenced, air traffic control issued a safety alert to the crew advising them to check their altitude. The minimum height recorded during the missed approach was 586 ft.
Figure 2: Flightpath of the descent below glideslope
Source: Recorded flight data and Google Earth, annotated by ATSB
After completing the missed approach, air traffic control repositioned the aircraft for another approach. During this repositioning, when the aircraft was 11.6 NM from the runway and flying level at 2,445 ft (1,259 ft below the glideslope – full-scale deflection), the crew re‑selected the ILS and commented that the EADI glideslope indication showed the aircraft to be on glideslope. The crew then completed a required navigation performance approach and landed without further incident.
After the aircraft had landed and the passengers had disembarked, the cockpit voice recorder captured the crew discussing the incident. During this discussion, the captain and first officer both stated that the EADI glideslope indications were constantly on glideslope until just before they commenced the missed approach when the first officer’s EADI indications moved rapidly up to show the aircraft as being very low. The captain’s EADI glideslope indication remained constantly on slope throughout and after the approach. Both crewmembers stated that no ILS or instrumentation failure indications were presented, and the captain also stated that the standby ILS indicator showed a constant on glideslope indication.
Context
Crew details
The captain held an air transport pilot licence (aeroplane) and class 1 aviation medical certificate. The captain had 6,277 hours of flying experience, of which 242 hours were on the Saab 340.
The first officer held a commercial pilot licence (aeroplane) and class 1 aviation medical certificate. The first officer had 455 hours of flying experience, of which 244 hours were on the Saab 340.
The ATSB found no indicators that the flight crewmembers were experiencing a level of fatigue known to affect performance.
Instrument landing system
An instrument landing system (ILS) is an instrument approach procedure that provides lateral (localiser) and vertical (glideslope) position information using angular deviation signals from the localiser antennas (located past the upwind end of the runway) and the glideslope antennas (located approximately 1,000 ft from the runway threshold). Aircraft systems detect these radio signals and provide instrument indications which, when utilised in conjunction with the flight instruments, enable an aircraft to be manoeuvred along a precise final approach path.
The Sydney runway 34L ILS approach included a 3° glideslope to the runway (Figure 3). During the incident approach, when the autopilot was re‑engaged, the groundspeed of the aircraft was 165 kt and the rate of descent required to descend along the glideslope at that groundspeed was about 876 ft/min.
Figure 3: Sydney runway 34 left ILS approach chart
Source: Airservices Australia, annotated by ATSB
The ILS ground equipment can emit false glideslopes at steeper than normal glideslope angles. The lowest of these typically occurs at about 9° to 12°, well above the flightpath of VH-VEQ during the incident approach.
Before and after the incident, a number of other aircraft completed uneventful ILS approaches to runway 34L, with no unusual indications reported by the crews of these aircraft.
Aircraft instrumentation
VH-VEQ was equipped with the Rockwell Collins Pro Line 4 electronic flight instrument system. This system used cathode ray tube displays to present flight and navigation information on the left (captain) and right (first officer) electronic attitude direction indicators (EADIs) and electronic horizontal situation indicators (EHSIs) (Figure 4).
The data presented on each side’s EADI and EHSI was provided by a corresponding display processor unit (DPU). The DPUs received data from numerous aircraft systems, including the navigation radios[3] and used the data to generate the required text and imagery for each display.
Figure 4: Saab 340 left (captain’s) flight instrumentation
Source: Link Airways, modified and annotated by ATSB
The ILS glideslope indication was presented on the right side of each EADI as fly-up or fly‑down commands on the glideslope indicator. Glideslope deviation was displayed with a centre marker and deviation dots (Figure 5). Full-scale deflection equated to about 0.7° of angular deviation from the nominal glideslope.
If the aircraft receiver malfunctioned, or the glideslope or localiser signals were invalid, a red glideslope or localiser indication (flag) should be presented on the respective erroneous EADI and standby ILS indications. If the DPU failed, a DPU fail indication should be presented on the EADI. No failure flags were reported on either EADI or on the standby ILS indicator during this incident.
Figure 5: Electronic attitude direction indicator
Source: Saab, modified and annotated by ATSB
Post incident examination and analysis
On the morning after the incident, an engineer tested the ILS instrumentation in VH-VEQ by simulating ILS data inputs to the DPUs. This testing found that the captain’s EADI presented a constant and erroneous on-glideslope indication while the standby and first officer glideslope indications were presented correctly. The captain and first officer’s DPUs were then removed and reinstalled in opposite positions and were again tested. This second testing found all 3 (captain, first officer and standby) glideslope indications were presented correctly.
Following the testing, the DPU found to be presenting faulty signals to the captain’s EADI during the incident was removed from service and sent to the manufacturer for examination. The examination found several damaged components within the unit, however it was not determined whether this damage contributed to the erroneous glideslope indications.
The manufacturer advised that, provided the signal from the navigation radio was valid, then information and indications derived from that signal would be displayed when that navigation radio was selected as the data source. The absence of any fault indications on the EADI indicates that the navigation radio was providing valid data, but that the data was likely outside of the normal data range scale. The manufacturer advised that the presentation of erroneous glideslope indications without any fault indication suggested an issue with the navigation radio.
Following the incident, the navigation radios were not tested or removed from the aircraft. No similar occurrences were reported in the subsequent operation of VH-VEQ.
The aircraft and avionics manufacturers advised that this incident was the first occurrence of its type on the Saab 340 or on any other Pro Line 4-equipped aircraft.
Ground proximity warning system
The aircraft was equipped with an enhanced ground proximity warning system (EGPWS). This system used aircraft inputs combined with internal terrain, obstacles, and airport runway databases to predict potential conflicts between the aircraft flight path and terrain or an obstacle.
The system also included a mode which detected excessive deviation below an ILS glideslope. The first level alert occurred when the aircraft was below 1,000 ft radio altitude with a deviation greater than 25% below the glideslope. In that case, a ‘glideslope’ aural alert was generated, and the caution light illuminated. Increases in deviation below the glideslope caused additional ‘glideslope’ alerts at increasing frequency. A second level alert occurred when the aircraft was below 300 ft radio altitude with a glideslope deviation of 40% or greater. This level generated a louder ‘glideslope’ alert every 3 seconds, continuing until the deviation was corrected.
Stable approach criteria
The operator’s flight crew operation manual stipulated that all flights must be stabilised by 1,000 ft above airport elevation in instrument meteorological conditions[4] and that flight crew must fly a stabilised approach to land at an aerodrome. The criteria to be met for an approach to be stabilised at 1,000 ft was:
• The aeroplane is either in level flight or on descent with less than 1,000 ft per min sink rate (unless required to meet specific approach criteria), and
• Below first stage flap and/or gear extension speed whichever is higher, and
• Not accelerating.
Note: To be considered stable, ILS approaches must be within one dot[5] of the glideslope and localizer and wings must be level below 300 feet AGL (except for minor corrections of less than 5 degrees angle of bank).
Despite the stabilised approach criteria and the advice on when a missed approach should be conducted, the PIC should go-around whenever they deem a missed approach is necessary.
Meteorology
At 1950, the time of the commencement of the missed approach, the Sydney Airport automated weather information service reported the wind as 7 kt from 330° magnetic. Cloud cover was reported as scattered at 821 ft above mean sea level (AMSL) and broken at 2,121 ft AMSL. Visibility was reported as 25 km.
Recorded data
Analysis of flight data from the flight data recorder showed the glideslope value indication presented on the captain’s EADI was fixed at 0.1 dots below glideslope throughout the occurrence. The glideslope indications presented on the first officer’s EADI and standby ILS indicator were not recorded.
As the aircraft descended below 1,000 ft radio altitude, the activation of the glideslope alert was recorded by the flight data recorder and cockpit voice recorder.
During the flight, no comment was made by either crewmember about the indications on the standby ILS indicator.
Safety analysis
Instrumentation fault
Following the incident, testing found the left (captain’s) display processor unit (DPU) to be faulty and it was removed from the aircraft and replaced. Since replacing the DPU, there have been no additional reports of erroneous glideslope indications on this aircraft. This indicates that the DPU was potentially the source of the false indications, although this could not be conclusively determined. The DPU was shipped to the manufacturer where a teardown of the unit was undertaken, and several failed components identified. However, when analysing the occurrence, the manufacturer reported that the failure indications were more consistent with an issue originating from the navigation radio. Both the aircraft and instrumentation manufacturers reported that this was the only known failure of its kind in the history of the aircraft type or on other aircraft equipped with the Pro Line 4 electronic flight instrument system.
While the precise source of the error could not be determined, it resulted in a constant on‑glideslope indication on the captain’s electronic attitude direction indicator (EADI) regardless of the aircraft's position relative to the glideslope. The indications were presented with no glideslope or DPU failure indication.
The first officer also reported similar erroneous indications on their EADI during the approach and made several comments about the glideslope that were recorded by the cockpit voice recorder. These comments often referred to a glideslope indication that differed from the recorded position of the aircraft. While the first officer’s glideslope indications were not recorded by the flight data recorder, these statements, the first officer’s reported observations and the recorded glideslope values indicated that the erroneous glideslope indications were also, at least intermittently, presented on the first officer’s EADI. However, as the aircraft descended below 1,000 ft, this EADI began presenting a correct fly‑up indication.
After the flight, the captain stated that the indications on the standby ILS indicator were also erroneous. The standby indicator’s input signals were not provided by the faulty DPU, and the glideslope indications displayed were not recorded by the flight data recorder. There was also no comment made by the crew referring to the standby ILS during the flight. Consequently, it could not be determined what indications were present.
Descent below glideslope and recovery
The erroneous on-glideslope indications were presented to the crew without any glideslope fault indications so the crew were not alerted to the instrumentation failure by the system. The aircraft commenced the approach at a position close to the glideslope. This positioned the erroneous indication close to the expected and correct glideslope indication. Furthermore, both EADIs very likely presented similar erroneous glideslope indications and the localiser indications were presented correctly. Therefore, when the autopilot did not descend the aircraft along the glideslope as anticipated, the crew were not immediately alerted to a potential instrumentation failure. Instead, the crew assessed that the autopilot was probably experiencing a lag in capturing the glideslope and the captain responded by disconnecting the autopilot and manually descending the aircraft to follow the glideslope.
The crew subsequently observed unusual glideslope indications and completed several altitude and distance checks in an attempt to understand the conflicting indications. As the aircraft descended close to the glideslope and with an on-glideslope indication, the captain re‑engaged the autopilot. However, this occurred when the aircraft was descending at an excessive rate for the approach, the implication of which did not appear to be recognised by the crew. As the aircraft continued the excessive descent rate, the instruments continued to show erroneous on-glideslope indications and the aircraft subsequently descended below the glideslope.
As the aircraft descended below 1,000 ft AMSL while significantly below the glideslope, the aircraft penetrated the ground proximity warning system warning envelope and a ‘glideslope’ alert sounded. At about the same time, the first officer’s EADI began showing correct glideslope indications. At that point the crew recognised the approach was unstable and immediately commenced a missed approach.
Findings
ATSB investigation report findings focus on safety factors (that is, events and conditions that increase risk). Safety factors include ‘contributing factors’ and ‘other factors that increased risk’ (that is, factors that did not meet the definition of a contributing factor for this occurrence but were still considered important to include in the report for the purpose of increasing awareness and enhancing safety). In addition ‘other findings’ may be included to provide important information about topics other than safety factors.
These findings should not be read as apportioning blame or liability to any particular organisation or individual.
From the evidence available, the following findings are made with respect to the flight instrumentation failure and descent below glideslope involving Saab 340, VH-VEQ on 24 October 2022.
Contributing factors
During an instrument landing system approach, an undetermined instrumentation fault resulted in an erroneous on-glideslope indication being presented constantly on the left electronic attitude direction indicator and intermittently on the right electronic attitude direction indicator.
The erroneous on-glideslope indications were presented without a fault indication and regardless of the aircraft's actual position relative to the glideslope. When the autopilot did not descend the aircraft along the glideslope as expected, the crew initiated a manual descent.
The crew subsequently re-engaged the autopilot as the aircraft descended at a rate exceeding that required for the approach. The autopilot maintained the excessive descent rate, and the aircraft descended significantly below the glideslope.
Other findings
As the aircraft descended below about 1,000 ft above ground level while about 380 ft below the glideslope, the ground proximity warnings system activated, and the crew recognised that the approach was not stabilised. In response, they commenced a missed approach.
Safety actions
Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to this occurrence.
Safety action not associated with an identified safety issue
Proactive safety action by Link Airways
Action number:
AO-2022-050-PSA-01
Action organisation:
Link Airways
Following the occurrence, the operator developed and implemented a standardised component reinstallation (re-rack) procedure based upon aircraft manufacturer guidance. This procedure aimed to reduce faults possibly created during defect troubleshooting.
Action number:
AO-2022-050-PSA-51
Action organisation:
Link Airways
The operator also issued an internal notice to maintenance personnel that provided guidance on the required items to be included in maintenance explanatory text. This notice also highlighted the importance of detailed explanatory information.
Sources and submissions
Sources of information
The sources of information during the investigation included:
Link Airways
the flight crew
the aircraft manufacturer
the instrumentation manufacturer
Bureau of Meteorology
Civil Aviation Safety Authority
Airservices Australia
recorded flight data and cockpit voice data from VH-VEQ.
Submissions
Under section 26 of the Transport Safety Investigation Act 2003, the ATSB may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. That section allows a person receiving a draft report to make submissions to the ATSB about the draft report.
A draft of this report was provided to the following directly involved parties:
Link Airways
the flight crew
Civil Aviation Safety Authority
the United States National Transportation Safety Board
the Swedish Accident Investigation Board
the aircraft manufacturer
the instrumentation manufacturer.
Submissions were received from:
the first officer
the United States National Transportation Safety Board
The submissions were reviewed and, where considered appropriate, the text of the report was amended accordingly.
Purpose of safety investigations
The objective of a safety investigation is to enhance transport safety. This is done through:
identifying safety issues and facilitating safety action to address those issues
providing information about occurrences and their associated safety factors to facilitate learning within the transport industry.
It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action.
Terminology
An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue.
Publishing information
Released in accordance with section 25 of the Transport Safety Investigation Act 2003
Ownership of intellectual property rights in this publication
Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia.
Creative Commons licence
With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence.
Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work.
The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau
Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.
[1]The flight was operated under Civil Aviation Safety Regulations Part 121 (Air transport operations - larger aeroplanes).
[2]Pilot Flying (PF) and Pilot Monitoring (PM): procedurally assigned roles with specifically assigned duties at specific stages of a flight. The PF does most of the flying, except in defined circumstances; such as planning for descent, approach and landing. The PM carries out support duties and monitors the PF’s actions and the aircraft’s flight path.
[3]The navigation radio is the aircraft instrument that receives the radio signals from the ILS ground stations. The navigation radio interprets the signal information and then provides data to the DPUs for presentation on the EADI and the standby ILS indicator.
[4]Instrument meteorological conditions (IMC): weather conditions that require pilots to fly primarily by reference to instruments, and therefore under Instrument Flight Rules (IFR), rather than by outside visual reference. Typically, this means flying in cloud or limited visibility.
[5]Each dot of glideslope deviation indication equals 20% of angular deviation.
The ATSB Annual Report 2021-22 outlines performance against the outcome and program structure in the Department of Infrastructure, Transport, Regional Development, Communications and the Arts' Portfolio Budget Statements 2021–22(Opens in a new tab/window)
I am pleased to be able to introduce this annual report on the ATSB activities for 2021–22, a year that continued to present challenges not just for the agency but for the transport sectors we serve due to the ongoing COVID-19 pandemic as well as challenging economic circumstances.
I commenced my term as Chief Commissioner and Chief Executive Officer on 2 September 2021, amidst lockdowns that saw our Canberra, Sydney and Melbourne staff all working from home. It is testament to our staff resilience and flexibility, and the robustness of the ATSB IT systems, that we were able to continue operations with minimal disruptions despite lockdowns, working-from-home requirements, and travel restrictions across the country.
On joining the ATSB I was also well aware that the ATSB is highly respected internationally for its best-practice transport safety investigation, a reputation I will uphold and build upon.
During 2021–22, the ATSB completed and published 60 complex and industry-significant investigation reports into transport accidents and incidents that provided the relevant transport modes with wide-ranging safety learnings. Among the higher profile investigations concluded during the year were:
The runaway and derailment of a loaded iron ore train south of Port Hedland, Western Australia, on 5 November 2018. The ATSB investigation established that the train operator’s risk assessments had limited focus on the potential causes of, and critical controls for preventing, a runaway event.
The evacuation of an A330 passenger aircraft at Sydney Airport, New South Wales, on 15 December 2019 – our investigation highlighted the importance of clear passenger information and commands, and resulted in the airline amending its safety material, cabin crew training, and other procedures as a result of the incident.
The near collision of passenger trains at Park Road Station, Brisbane, on 25 March 2019, following a signal passed at danger (SPAD). Our investigation found that change management relating to the moving or installation of signal aspect indicators, to facilitate the rollout of new rollingstock, did not provide sufficient detail to ensure consistent and conspicuous placement on platforms.
The collision of a fishing vessel with a bulk carrier in darkness near the entrance to Port Adelaide Harbour, South Australia, on 29 February 2020, where we flagged our ongoing concern about collisions between trading ships and small vessels on the Australian coast.
The mid-air collision of 2 twin-engine training aircraft near Mangalore Airport, Victoria, on 19 February 2020, fatally injuring four pilots. The accident was the first mid-air collision in Australia between 2 civilian aircraft operating under instrument flight rules procedures that have been in place for many decades, and our investigation highlighted the potential for ‘ADS-B IN’ technology to improve pilots’ situational awareness in non-controlled airspace.
In addition to ATSB-led investigations, independent investigation agencies in New South Wales and Victoria conduct rail investigations in their jurisdictions on behalf of ATSB under the Commonwealth Transport Safety Investigation Act 2003 (TSI Act). In 2021–22, the ATSB published and promoted 5 rail safety investigations conducted by the New South Wales Office of Transport Safety Investigations (OTSI) and one rail safety investigation conducted by Victoria’s Chief Investigator, Transport Safety (CITS).
The investigations published in 2021–22 identified no fewer than 56 safety issues – factors that if unaddressed have the potential to adversely affect the safety of future operations. Safety issues are characteristic of an organisation or a system, rather than an individual or an operational environment at a specific point in time.
Further, I am pleased to confirm that no changes to published investigation findings were required in 2021–22, evidence of the ATSB central commitment that all published investigations are factually accurate, defendable and evidence-based.
In 2021–22, the ATSB also:
initiated 51 new aviation occurrence investigations, 6 new marine occurrence investigations, and 5 rail occurrence investigations published 15 occurrence briefs, which are short reports that allow us to share safety learnings from a transport safety occurrence that did not meet the threshold of requiring investigation under the TSI Act
received and processed 115 notifications under the REPCON confidential reporting scheme, of which 49 were assessed and classified as meeting the REPCON criteria – during the year, 37 REPCON reports were completed, of which 22 (59%) resulted in safety action being taken by stakeholders
commissioned our new ATSB Investigation Management System (AIMS), a cloud-based IT system used to manage all aspects of our investigations, including logging occurrence notifications, electronic evidence storage and record management for physical evidence, assigning tasks, and recording effort to manage report approvals and distributions
commissioned purpose-built state-of-the-art technical facilities in our Canberra office that will enhance our ability to conduct detailed technical examination of evidence from accident sites.
Outlook
The upcoming 2022–23 period promises to be a year of consolidation as we plan for a more sustainable future for the ATSB. I am aware of the calls stemming from a number of inquiries and associated reports, seeking to extend the ATSB services through an expanded remit. The ATSB will provide input into those inquiries as required.
However, any decisions to change the ATSB remit are a matter for government. It is my immediate priority to address the ATSB existing budgetary challenges – specifically the shortfalls in rail investigation resources resulting from unsustainable funding arrangements outside our core appropriations.
To better position the agency to face the challenges ahead, and to ensure we are making the most effective use of our resources, in 2021–22 I initiated the development of a new strategic plan for the ATSB. This plan, which I intend to publish in early 2023, will set out the ATSB priorities and the actions we will take to ensure we are best positioned to fulfil our responsibilities to government and deliver best practice transport safety investigations for the greatest public benefit.
It will focus on enhancing our best-practice approach to investigations, engaging with stakeholders and influencing improvements in transport safety, fostering our organisational resilience, and affirming our role as the national transport safety investigator.
I look forward to supporting our staff in delivering that plan
Beechcraft Baron heater fuel supply line inspection
The ATSB is encouraging Baron operators to inspect the heater fuel supply line and nearby wiring in the aircraft cockpit to reduce the risk of an in-flight fire.
What happened
At approximately 0835 on the morning of 16 April 2022, the pilot of a Beechcraft B58 Baron registered VH-NPT commenced an approach to Runway 12 at the East Kimberley Regional Airport near Kununurra. Upon selection of the landing gear to the down position the pilot reported multiple unusual indications, the gear failed to extend and smoke started to emerge from forward of the pilots side circuit breaker panel. By the time the pilot had declared a PAN, flame was emerging from the same location as the smoke. The pilot expended the aircraft’s fire extinguisher but the fire returned. Smoke and flame continued to effect the pilot until the aircraft collided with terrain where it was consumed by a significant post impact fire. The pilot sustained serious injuries and the single passenger onboard was fatally injured.
Related Occurrence
During the initial phase of the investigation the ATSB identified a similar occurrence that had been investigated in 2014 (
). The investigation of the in-flight cockpit fire found that electrical wiring had chaffed through the heater fuel supply line causing it to arc and burn a hole in the fuel line. This provided an ignition source and accelerant for the fire.
Why did it happen
Both the heater fuel line and the aircraft wiring of NPT were consumed by the post impact fire, and an examination was not possible. However, the location, initiation and severity of the fire is similar to the incident detailed in AO‑2014‑040. As such, while the specific circumstances of the fire initiation and acceleration remain under investigation, in the interest of transport safety, the ATSB has issued this safety advisory notice.
Manufacturer Response
In response to the advanced release of this ATSB SAN the manufacturer advised that there is a potential for chafing of wiring across several Beechcraft models including the Baron. Model Communiqué 116 references wire chafing reports in the Beechcraft Bonanza but the communiqué states that the protection of wires from chafing damage is applicable to all Beechcraft models.
Safety advisory notice
AO-2022-026-SAN-001: The ATSB encourages operators of Beechcraft Baron aircraft to conduct a detailed inspection of the heater fuel supply line and wiring in its vicinity. The examination should focus specifically on the area below the pilot’s circuit breaker panel and areas forward of this under the instrument panel. Any identified issues should be reported to CASA (via the defect reporting system) and the manufacturer.
The ATSB encourages Baron operators to review the Electrical Wire Chafing Protection section in Model Communiqué 116 (See attachment A) put out by Beechcraft in June of 2008, which is applicable to all Beechcraft models.
The ATSB further encourages operators to review the anti-chafing provisions within the relevant aircraft maintenance manual (see 20-04-00-001 – Electrical Wiring – Description and Operation) to ensure serviceability of anti-chafing materials and replace or fit, as necessary. Specific consideration should be given to wiring in the vicinity of lines carrying flammable liquids.
ATSB comment
The ATSB notes similarities in several Beechcraft models, that utilise fuel lines running through the cockpit. While a review of ATSB data does not support the broadening of the SAN to include other aircraft models, chafe protection should be applied to wiring as per the manufacturers' requirements and particular care should be taken when wiring is in the proximity of lines carrying flammable liquids.
Area of concern in an exemplar Baron B58 showing the location of the fuel line and wiring looms. Inspection should encompass any areas along the fuel line where it may contact wiring looms.
I am pleased to present the Australian Transport Safety Bureau’s (ATSB) Corporate Plan, which covers the period 2022-23 to 2025-26.
This Corporate Plan has been prepared consistent with paragraph 35(1)(b) of the Public Governance, Performance and Accountability Act 2013 and the relevant provisions of the Transport Safety Investigation Act 2003 (the TSI Act), which establishes the ATSB. The Corporate Plan is also consistent with the Minister’s revised Statement of Expectations 2021–23 (SOE) for the ATSB, as notified under Section 12AE of the TSI Act. The SOE sets out clear expectations that the ATSB’s resources be used in an efficient, effective, economical and ethical way, following best practice principles and guidelines.
I acknowledge this continues to be a time of great uncertainty for the transport industry in general, and aviation in particular. As an independent safety agency, the ATSB is continuing to apply our safety knowledge and expertise and carefully monitoring the return to safe and reliable transport operations. As an operational agency, the ATSB continues to deploy accident investigation teams where and when necessary during this pandemic.
I look forward to working with the newly elected Federal Government, to ensure the Bureau is well positioned to meet the Minister for Infrastructure, Transport, Regional Development and Local Government’s expectations for the ATSB’s role in improving transport safety. I acknowledge the ongoing uncertainty for Australia’s transport industries operating in an evolving COVID-normal environment and the challenging economic conditions that these sectors face. I am also mindful that such challenges will need to be internally managed to ensure the ATSB maintains its ability to undertake and meet prescribed functions and key deliverables.
I have been the ATSB’s Chief Commissioner for 12 months now. I am aware of the calls stemming from a number of inquiries and associated reports, seeking to extend the ATSB’s services through an expanded remit. The ATSB will provide input into those inquiries as required. However, any decisions to change the ATSB’s remit are a matter for Government. It is my immediate priority to address the ATSB’s existing budgetary challenges – specifically the shortfalls in rail investigation resources resulting from unsustainable funding arrangements outside our core appropriations.
In my time as Chief Commissioner the ATSB has demonstrated itself to me as a highly capable organisation. In the past 12 months we have released a number of complex and industry significant reports that carry wide-ranging safety implications to the relevant transport modes; one such report is the ATSB’s investigation into the mid-air collision near Mangalore Airport in Victoria in 2020. The investigation highlighted the importance of air traffic hazard assessment and the value of aircraft owners installing Automatic Dependent Surveillance-Broadcast (ADS-B) devices to assist pilots with the identification and avoidance of conflicting traffic. Other significant investigations include an investigation into a level crossing accident north-east of Kalgoorlie in Western Australia in 2021 highlighted the risks of driver distraction and the consequences when heavy vehicles and trains operate in the same geographical space and, an investigation into a collision between a bulk carrier and a fishing vessel off the entrance to Port Adelaide in South Australia in 2020 highlighted the need for crew to keep a lookout by all available means including use of radar, radio and automatic identification systems.
As a relatively small operationally-focused agency, the ATSB will need to anticipate change and adapt to ensure we are meeting the needs of government, industry, and the traveling public. Accordingly, I have been working with staff from across the agency to develop a strategic plan that clearly identifies the key objectives, strategies and actions to be given priority over the short to medium term. The plan, to be released this financial year, will have a focus on:
enhancing our products and stakeholder engagement for improving transport safety
fostering organisational resilience
affirming our role as the national transport safety investigator.
An example of the immediate action we are taking, is the greater utilisation of audio-visual content which will increase consumption of our investigation reports and advance important safety messaging. Stakeholders can also expect the ATSB to produce more statistical and research-based outputs ensuring we are making the best use of available data and the specialist capabilities of our people. We will balance these actions with our core occurrence investigation activities which must continue to be managed within our demand/capacity limitations as this will enable us to expedite production and publishing timeframes.
The strategic plan will position the ATSB to be able to provide greater value for persons and organisations seeking to use our products to take safety action.
Based on my recent interactions with a range of prominent overseas safety investigation bodies, it is evident the ATSB is considered a highly reputable agency and world leading. As Chief Commissioner, I am fully committed to continuing to work innovatively and collaboratively with all relevant stakeholders to enhance and amplify our contribution to improving transport safety both domestically and internationally.
The ATSB continues to work towards achieving its new performance measures established in the 2020-21 Corporate Plan. Through revised performance criteria, we are focused on improving our timeliness, demonstrating safety action taken in response to our investigations, ensuring our findings are defendable, and using our resources efficiently and effectively.
All aircraft types do not spin and recover in the same way. Know your aeroplane type, what recovery techniques will work and what recovery techniques will not work.
What happened
On 23 June 2021, while conducting spin entry and recovery training from 5,800 ft above ground level, the Cessna A150M Aerobat did not fully recover from a spin to the left before impacting terrain.
Factors uncovered during the investigation
The aerobatics instructor was experienced in conducting spins, primarily in the Pitts Special aircraft type. However, it was likely that they had no experience in spinning a Cessna A150 Aerobat or any similar variant.
The instructor’s theoretical spin training provided to the aerobatic student pilot (and another student at the same time) did not include instruction on the recovery technique as prescribed in the Aerobat pilot’s operating handbook (POH). Further, the ATSB established that it was likely the instructor intended to practice 2 spin recovery techniques (Mueller/Beggs and PARE). The technique broadly known as the Mueller/Beggs recovery method, has been shown to not recover a Cessna A150 Aerobat established in a spin to the left. However, the PARE method was similar to Aerobat POH method, with less emphasis on the brisk full forward movement of the control yoke.
: The ATSB strongly encourages all aerobatic pilots and aerobatic flight instructors to be aware:
the Mueller/Beggs method of spin recovery does not recover all aircraft types from a spin
the Mueller/Beggs spin recovery method limitations should be emphasised during spin theory training
the Mueller/Beggs method of spin recovery will not recover a Cessna A150 Aerobat or similar variants from a spin in some circumstances
they should review the pilot’s operating handbook of the aircraft type that they intend to operate for the recommended spin recovery technique
prior to doing spins in any model aircraft, pilots should obtain instruction and or advice in spins from an instructor who is fully qualified and current in spinning that model.
