Investigation summary

What happened

On 8 September 2025, the pilot of an Air Tractor AT-802A agricultural aircraft, registered VH-ODX and operated by Aerotech Australasia, was conducting aerial application operations in fields to the north of Cummins Town aerodrome, South Australia. At around 1323 local time, during the seventh load of the day, the pilot attempted to fly under 2 intersecting and closely spaced powerlines, at a point where there was a pole suspending the second powerline directly ahead on the aircraft’s path. The aircraft passed under the first powerline and the pilot conducted a right turn away from the pole ahead. During this turn, the aircraft contacted the crop and ground. After passing under the second powerline, the aircraft climbed, rolled inverted and collided with terrain in an inverted position. The pilot was fatally injured, and the aircraft was substantially damaged.

What the ATSB found

The ATSB found that the pilot had been flying in the vicinity of intersecting powerlines, the second of which converged with the aircraft’s successive spray pass tracks, reducing the distance between them. On the accident pass, there was about 240 m between the powerlines, with a pole directly in front of the aircraft. Compared to previous passes, there was less distance available for the pilot to manoeuvre the aircraft and maintain separation from the powerline and poles.

During the turn to avoid the pole, the aircraft became established in a significant right skid with a right roll attitude. The aircraft’s right wheel, spray boom, aileron and wingtip contacted the crop and ground. Once clear of the second powerline, likely with a large left aileron input, the aircraft pitched up and the right wing aerodynamically stalled. The aircraft then rolled inverted at a height from which recovery was not possible.

Post-mortem toxicology identified that the pilot had likely used cocaine within the 24 hours prior to the accident. However, it was determined unlikely that the pilot was directly affected by the drug at the time of the accident.

What has been done as a result

Following this accident, Aerotech amended its operations manual to include additional guidance on managing hazards during aerial application operations. Its aircraft fleet was being configured with the latest Tabula GPS systems and advised that GPS hazard marking and alerting would be set up prior to departure. 

Aerotech has further developed its risk register and implemented a human factors and non-technical skills program.

Safety message

Powerlines and their associated poles present a significant hazard for aerial application operations. The configuration of powerlines across fields is variable, therefore no single solution or approach can be used. The Aerial Agricultural Association of Australia’s Aerial Application Pilots Manual contains guidance for operations near powerlines and pilots are encouraged to review this on a regular basis. This accident presents a reminder of the importance of thorough planning, preparation and inspections prior to conducting spraying and to carefully consider the risks of flying in proximity to multiple, closely situated powerlines. 

While no direct contribution was drawn with this accident, illicit substances are incompatible with safety sensitive aviation activities. The actual effect of illicit substances on the safety of flight cannot be predicted by users and periods of impairment beyond the anticipated effects can occur.

The occurrence

On 8 September 2025, at about 0937 local time, the pilot (and sole occupant) of an Air Tractor AT-802A agricultural aircraft, registered VH-ODX and operated by Aerotech Australasia,¹ departed from the Cummins Town aerodrome, South Australia. The pilot ferried the aircraft to a private airstrip approximately 22 km to the north, which was to be used as a supply point for the day’s aerial spraying activities. 

During the ferry flight, the recorded flight data showed that the pilot diverted right of the direct track to overfly the fields to be sprayed that day, before arriving at the supply airstrip at 0946 where they were met by the loader.² The tasking for the day was the aerial application of 13 loads of fungicide and insecticide across 2 wheat fields (‘Field 1’ and ‘Field 2’ in Figure 1).

Figure 1: Fields to be sprayed and transit route

Powerlines spanned the fields of the property being sprayed. These, and a tower hazard, were included on the work order provided to the pilot prior to the flight (Figure 2). Field 1 featured a 19 kV single‑wire earth return powerline crossing the southern section in an east-west direction (Figure 2).

Figure 2: Hazards in the fields to be sprayed

Field 2 had 5 19 kV single‑wire earth return powerlines at a height of about 12 m above the ground (Figure 3):

• a north-south powerline on the eastern side of the field
• a second north-south powerline on the western side of the field
• an east-west powerline with a deviation to the west-south-west in the western third of the field
• two smaller powerlines extending north from the east-west powerline.

Figure 3: Field 2 hazards

At 1005, the flight departed for application of the first load on Field 1, about 11 km to the south-south-east. Recorded data from the aircraft identified the field was sprayed in a north-south racetrack pattern³ until the hopper was emptied, before returning to the supply airstrip. This operation was repeated a further 3 times. The pilot flew mostly under the powerline in Field 1 but occasionally flew over it where there was a power pole directly on track. They also flew over the powerline where it merged close to the edge of the field. There were several locations where the aircraft track was close to a pole. The pilot still flew under the powerline in those locations but diverged left or right as required to avoid the pole.

The pilot completed spraying Field 1 during the fourth load, including a clean-up run⁴  along the south fence line. They then transited 5 km north to Field 2.

On arrival at Field 2, the pilot flew around a known tower hazard, then partially along the east and west-south-west powerline. They then completed the fourth load, spraying in an east-west racetrack pattern. Another 2 loads were completed, including another clean up run along the north-south powerline on the western side of the field at the end of load 5 (Figure 4). The recorded data showed the pilot mostly flew under the north-­south powerline running perpendicular to the spray passes, except where the powerline ran adjacent to the edge of the field, where they flew over the powerline.

Figure 4: Field 2 – loads 4 (green), 5 (yellow), 6 (salmon) and 7 (white)

At about 1307, the pilot departed the supply airstrip to commence their seventh load at Field 2. During the first 9 passes of that load, the aircraft tracks became progressively closer to the west-south-west powerline, which converged towards those tracks. The pilot encountered poles at several locations on the west-south-west powerline and climbed over them (and the powerline) when they were directly on track. On one pass, the pilot diverged right of track to avoid a pole while flying under the powerline. Approximately 16 minutes into the load, while heading west on pass 10, the pilot flew under the north‑south powerline. At that point, the west-south-west powerline crossed the north‑south powerline (and pole) 40 m to the north. That pass also aligned with another power pole on the west-south-west powerline, 240 m beyond the north‑south powerline (Figure 5).

Recorded data showed the aircraft maintained its spray height and conducted a right turn away from the pole ahead. During this turn, the aircraft’s right wheel, right spray boom and right aileron and wingtip contacted the crop. The right wheel also contacted the ground. The aircraft then passed underneath the second powerline and climbed, after which it rolled inverted and collided with terrain at 1323. The aircraft came to rest on a farm road about 150 m beyond the second powerline. The pilot was fatally injured, and the aircraft was substantially damaged.

Figure 5: Final pass within Field 2 showing the flight path (in blue) and accident site relative to the powerlines and poles (yellow circles)

Context

Pilot information

Qualifications and experience

The pilot held a Commercial Pilot Licence (Aeroplane) with a single-engine aeroplane class rating. The pilot had 3,623 hours total aeronautical experience, of which 1,243 hours were conducting agricultural aerial application and 941 hours were on the AT‑802 aircraft type. The pilot also held aerial application (with firefighting endorsement) and low-level ratings. In addition, the pilot held a gas turbine design feature endorsement, and numerous piston and turbine type ratings. 

The pilot held a valid class 2 aviation medical certificate with their class 1 medical certificate not being renewed when it expired in November 2023. For the operation being conducted, only a class 2 medical certificate was required.⁵

Recent history

The 2 days prior to the accident were the weekend and the pilot’s partner reported a relaxed weekend with social activities with friends.

Mobile phone records showed that the pilot made a phone call (that was not answered) at about 2230 on the night before the accident. On the morning of the accident, the pilot was reported to have woken at about 0500 and left home at 0513. While it was not possible to determine the pilot’s sleep period, it was likely they had opportunity to have slept for about 6 hours. 

The pilot was originally scheduled to ferry the aircraft from Cummins Town to Adelaide, South Australia, for maintenance, however, they could not depart due to fog and had access to rest facilities while waiting for the fog to clear. The pilot was later advised that the maintenance requirement would be deferred. The pilot’s partner called and spoke to the pilot at 0700 after having woken them up. The pilot mentioned that they would go back to sleep after that phone call. The partner called the pilot again at 0900, at which time the pilot was at a cafe. They recalled that the pilot seemed their normal self. They also reported that a friend, who saw the pilot on the morning, spoke with the pilot and did not observe any unusual behaviour.

The loader who provided ground assistance to the pilot that day did not observe any indications that the pilot was fatigued and reported that the pilot was ‘OK’ in the morning. The loader also reported that later, the pilot seemed a bit distant which was unusual and that the pilot remained in the aircraft all day. In response to the draft report, the operator stated that they expected the pilot to remain in the aircraft as the task required loading fuel and chemical into the aircraft without shutting it down. 

The 6 hours available for the pilot to sleep on the previous evening was sub-optimal, with most people requiring between 7 to 8 hours sleep (Watson and colleagues, 2015). However, had this period been fully utilised (had the pilot obtained 6 hours sleep), the sleep restriction would not be consistent with an acute fatigue risk (Dawson and McCulloch, 2005). It was not possible, however, to determine the quantity or quality of the sleep that the pilot was able to achieve that night, or while waiting for the fog to clear. Therefore, the ATSB was unable to establish whether the pilot was affected by fatigue at the time of the accident.

Aircraft information

VH-ODX was an Air Tractor Incorporated AT-802A single-seat low-wing tailwheel, fixed landing gear aircraft manufactured in the United States in 2006. It was powered by a Pratt & Whitney Canada PT6A-67AG turboprop engine. It was first registered in Australia in August 2006. The aircraft was configured for aerial spraying, with a spray boom fitted under each wing, aft of the trailing edge, and extending about three-quarters of the wingspan (exemplar shown in Figure 6).

Figure 6: Exemplar AT-802 showing spray boom installation

The current maintenance release was issued on 30 July 2025. On the day of the accident, the maintenance release indicated the aircraft had 5,595.4 hours recorded as the total time in service. There were no defects noted on the maintenance release.

Meteorological information

The Bureau of Meteorology operated a weather station at Cummins Town aerodrome, 17 km to the south of the accident site, which recorded wind and temperature at 30‑minute intervals. Around the time of the accident, the recorded winds were 11 kt from the west and the temperature was 19°C.

The loader reported the weather at the time of the accident to be clear and sunny with a light westerly breeze.

Recorded information

Tracking device

A TracPlus RockAIR portable tracking device had been fitted to the aircraft and was recovered from the accident site. The device was transferred to the ATSB’s technical facilities in Canberra, Australian Capital Territory, where it was interrogated. The recorded data provided the aircraft’s position, altitude, speed and track angle data at 1‑second intervals up until the time of the accident. The data showed the take‑off from Cummins Town aerodrome, the transit to and from the supply airstrip and the completed spray runs in fields 1 and 2. Location and time parameters from the flight data were correlated to identify that the accident occurred at 1323:40.

The recorded data showed that, in addition to overflying the fields to be sprayed, the pilot flew along/parallel/in close proximity to the known hazards as depicted in the work order, consistent with an inspection of these hazards being made. This included the powerlines in the vicinity of the accident site during the fourth load (Figure 7). However, there was no record of what the pilot observed or what their assessment of those hazards was.

Figure 7: Aircraft track near known hazards in Field 2 during the fourth load

Prior to the accident pass, the pilot had completed 9 passes on their seventh load in Field 2. Passes 2, 4, 6, 8 and the accident pass (pass 10) were all flown in a westerly direction towards the previously described powerlines.⁶ On each of those passes, the pilot flew under the north-south powerline, towards the west-south-west powerline, which converged with the aircraft’s track (Figure 8). On each pass, the distance between the 2 powerlines became progressively shorter as follows:

• Pass 2. There was about 880 m between the powerlines, and the pilot flew over the converging powerline.
• Pass 4. There was about 750 m between the powerlines. The pilot flew over the converging powerline where there was also a pole, which was directly on its path.
• Pass 6. There was about 560 m between the powerlines. The pilot climbed the aircraft above the converging powerline and its poles as well as flying over the smaller north powerline.
• Pass 8. There was about 380 m between the powerlines. The pilot flew under the converging powerline but diverged slightly right of the planned track to fly between 2 poles suspending the powerline, passing within 25 m abeam of the pole they were to avoid on the next pass (pass 10).
• Pass 10 (accident pass). The distance between powerlines was 240 m. As previously described, the aircraft did not climb and the pilot commenced a right turn away from the pole, then flew under the converging powerline.

On the accident pass, the aircraft was flown at a height of about 15–18 ft (5–6 m),⁷ at a groundspeed of about 130 kt.⁸ During the contact with the ground, the speed slowed to about 107 kt. After passing the converging powerline, the data showed that the aircraft climbed approximately 30 ft (10 m) in height, and its groundspeed slowed to about 87 kt.

Figure 8: Comparison of spray passes 6, 8 and 10 near the accident site

Agricultural application system

To assist with aerial application tasks, a Tabula AirVision agricultural application system was fitted to the aircraft. The system had the capability to record parameters such as position and application information. It could provide live fleet tracking and also had a wire warning system. The unit was recovered from the aircraft and retained by the ATSB for further investigation.

The Tabula system manufacturer assisted with analysis of the device and advised that there was no indication that any of the settings on the device had been changed within 10 minutes of the accident. They explained that the wire warning system required an operator to input known wires or hazards into the system and when nearing those wires or hazards the system would provide a warning message on the display and light bar. However, this functionality was not in use at the time.

Engine parameters

A Perkins Data Acquisition Alarm Monitor was recovered from the aircraft and retained by the ATSB for further investigation. This device recorded 12 engine parameters at a frequency of 10 Hz and showed that the engine was producing power prior to the collision with terrain. A Replay XD 1080 video camera mount in the cockpit was also recovered. Data extracted from the unit contained about 30 GB of good quality video, however, the last recording was from 2016.

Wreckage and impact information

Site information

Witness marks matching the right wheel, right spray boom and right wingtip indicated that those components had passed through the 0.5‍–‍1.0 m high wheat crop 260 m prior to the impact with terrain, with the right wheel running along the ground for about 22 m (Figure 9 and Figure 10). The crop markings started on a heading of 264° (magnetic), ran for about 125 m and finished just beyond the west‑south‑west powerline on a heading of 273°. The markings showed that the aircraft was in a significant right skid.⁹ Later in the crop markings, a scar corresponding to the right aileron indicated a significant down (left roll) deflection. The aircraft did not contact the powerline.

Another crop and ground scar from the aircraft existed 88 m beyond the initial markings that continued to the wreckage (Figure 9). Numerous indicators such as component locations in the debris field, orientation of wheat strands caught in the aircraft structure, and damage signatures to the airframe indicated the aircraft impacted terrain in an inverted orientation, left wing first at a near wings-level and nose-down attitude.

Figure 9: Crop witness marks at the accident site

Figure 10: Alternate view of crop witness marks

Wreckage examination

All major aircraft components were accounted for at the accident site (Figure 11). There was no evidence of pre‑impact defects with the flight controls or aircraft structure. The propeller assembly separated from the engine during the impact sequence and was located on the farm road, about 18 m behind the front of the fuselage. Two propeller blades had ejected from the propeller hub and one blade had fractured mid‑length. The damage sustained to the propeller assembly was consistent with the engine operating at the time of the ground impact. The wing integral fuel tanks had ruptured during the accident sequence, however, there was no post‑impact fire. Residual aroma from spilled fuel was detected at the accident site.

Figure 11: VH-ODX wreckage

Crop markings analysis

The ATSB took measurements of the crop markings, which were identified as being made by the right wheel, right spray boom, right aileron and right wingtip of VH-ODX. The measurements were analysed to determine the skid and roll angles of the aircraft.

The skid angle was determined using measurements of the right wheel markings with comparisons against the respective measurements between the right wheel to spray boom and wing tip markings. It was concluded that, by time the right wheel had ceased contact with the crop, the skid angle was likely around 30°.

The roll angle was calculated using direct measurements of the crop scything, corrected for the wing dihedral.¹⁰ The angle progressively increased from the wing’s first contact with the crop to greater than 30° (to the right) when the right wheel had last contact with the crop. At that point the left wingtip was calculated to be 8 m higher than the right wheel, which was about 0.5 to 0.75 m off the ground, leaving around 2 to 3 m clearance from the powerline above. There was no physical evidence found to conclude the left wingtip made contact with the powerline.

The right wheel leaving the crop was indicative of the aircraft having pitched up and the crop markings showed the application of a left aileron roll input. 

The data points and calculations indicated that, as the aircraft passed under the second powerline, the aircraft yaw and roll angles were increasing. However, there was evidence that the pilot was applying left aileron (opposite to the roll) and back (up) elevator inputs, likely in an effort to increase clearance from the terrain.

Operational information

Field inspections and powerlines 

The Aerotech Standard Operations Manual for Application Operations, included the following information regarding field inspections and operating in proximity to powerlines:

D1.8 Inspection of treatment area

Pilots should carry a facsimile of a map of the treatment area if possible. The originals of these maps should be kept in either hard copy or electronic file. Despite the existence of a map, in daylight operations, the pilot should carry out an inspection of the treatment area to locate any obstacles. A personal paddock inspection checklist should be used for the inspection process – a copy of a standard paddock inspection checklist can be found at A6.15.

Prior to any clean-up runs at the conclusion of a job, an extra hazard check must be made.

…

D1.9 Powerlines

The decision to work over or under powerlines is up to the pilot. From the Applications Pilots Manual are the following comments;

a)     Flying under wires is not only safer than pulling up over them – since the only judgement involved is that normally needed for maintaining spray height – but simplifies the whole job.

b)     Flying under wires should only be attempted when you are sure that there is room, time and the absence of other distractions.

c)     There must be sufficient time to settle down at the correct spraying height before reaching the wires.

Any decision based on flying under a wire must be on the assumption of maintaining the aircraft at the normal spraying height. If it will be necessary to fly lower than usual to pass under the wire, then a manoeuvre over the wire is to be taken.

In addition to the powerline guidance in the Aerotech operations manual, the Aerial Application Pilots Manual (Aerial Agricultural Association of Australia, 2011) also stated:

Only when you are completely sure that there is adequate and safe clearance should the decision to fly under be taken. A practical method of ascertaining clearance is to fly the aircraft at spraying height parallel to the wires and look at the clearance. Whilst doing so watch out for other obstructions, particularly branch and guy wires!

No attempt should be made to fly under a low wire if at the same time your attention is likely to be diverted from maintaining the correct height by some other object such as a fence. If the temptation to fly a little lower beneath the wire proves too strong there may be some chance of getting away with a gentle contact with open ground: contact with a fence is likely to be disastrous.

When flying parallel to a wire run always check two poles ahead for indications of other wires, such as extra cross trees, insulators etc.

The cardinal rule: having decided that you can safely fly under a wire all you have to do is concentrate on maintaining your normal spray run – nothing else. Don’t look up at the wire – you will almost inevitably pull up towards it!

Pilot comments on the powerlines

When discussing the powerlines in Field 2, the chief pilot expressed to the ATSB that they would have flown over the powerlines in that particular corner of the field. Another senior pilot believed there was insufficient distance to climb over the pole and powerline after passing the north-south powerline and that they would not attempt a similar turn to avoid the pole in that situation. They did note, however, that the pilot did avoid the pole.  

Aerodynamic stall 

A wing generates lift when the airflow around the upper and lower surfaces results in a pressure difference between those surfaces. At a typical angle of attack (the relative angle between the chord line of the wing and the approaching airflow) of around 12–16°, which is a characteristic of the wing design, the flow over the upper surface of the wing separates from the surface. This condition is known as an aerodynamic stall (or simply a stall) and results in a rapid reduction in the lift generated and an increase in drag. Due to the sudden reduction in lift from the wing and rearward movement of the centre of lift, an uncommanded nose-down pitch ensues. 

A wing drop occurs when one wing stalls before the other and can lead to an incipient spin. This characteristic can be exacerbated by uncoordinated (or ‘unbalanced’) flight such as when the critical angle of attack is exceeded in a crossed control situation, where aileron is applied in one direction and rudder in the opposite direction.

As a loss of altitude also occurs during recovery from a stall, a stall at low-level could leave insufficient height above the ground to recover. The Pilot’s Operating Handbook for the AT-802A stated that the maximum altitude lost during a wings level stall recovery at maximum gross weight was 280 ft. At this weight, with power off and wings level, the aircraft stall speed was 91 kt (indicated airspeed).

The handbook also stated: 

… if the aircraft is inadvertently placed in an impending stall situation, it is only necessary to relax some back pressure on the stick to make recovery, and little altitude is lost, providing the turn is coordinated. A stall from a skidding turn will result in the nose dropping sharply with a significant loss of altitude. 

Medical and pathological information

A post-mortem examination was conducted by a qualified pathologist on behalf of the South Australia Coroner. The examination did not report any signs of natural disease or illness in the pilot.

Toxicological analysis was also performed and noted:

• no alcohol was detected
• carboxyhaemoglobin (carbon monoxide)¹¹ was detected at a concentration of 2%, which was considered within the normal range for a non-smoker
• benzoylecgonine (a metabolite of cocaine) was detected, at a concentration of 0.36mg/l
• ecgonine methyl ester (a metabolite of cocaine, also known as methylecgonine) was detected, at a concentration of 0.048mg/L
• no unmetabolised cocaine was detected.

The ATSB engaged a forensic pharmacologist to examine and interpret the toxicological results. The pharmacologist indicated that benzoylecgonine is the primary metabolite of cocaine and the presence of this confirmed the usage of cocaine. The pharmacologist stated:

• While it was not possible to precisely determine when the pilot had used cocaine, they estimated the pilot had consumed cocaine within 24 hours prior to the accident. 
• The witness report of the pilot’s state did not suggest acute effects of cocaine, nor would acute intoxication be expected based on the concentration of the metabolite benzoylecgonine.
• Cocaine users can experience impairment following the initial effects of drugs. This acute withdrawal phase can last 9 hours to 4 days. During this period, symptoms can include feelings of depression and irritability, and there can be significant fatigue and lack of energy (Isenschmid, 2002).

Drug and alcohol management plan

The risk of drugs and alcohol in aviation was managed by Civil Aviation Safety Regulation Part 99. Part 99 required certain organisations to implement a drug and alcohol management plan (DAMP) to govern employees and contractors who were engaged in safety sensitive aviation activities (SSAA). SSAA roles are those that might affect the safe conduct of aircraft operations.

Aerotech had implemented a DAMP in accordance with the regulations. This plan outlined the roles and responsibilities of key personnel and the obligations of employees. 

The plan required all SSAA employees to attend a drug and alcohol education program. This was achieved through the CASA online education portal and refreshers were required at intervals of no longer than 30 months. A testing program was also in place and tests were to be conducted:

• prior to commencement in a role performing SSAA
• post-accident or serious incident
• on reasonable suspicion
• on return to SSAA work (if associated with an alcohol or drug related incident).  

The pilot had last completed their DAMP training in August 2025, which was valid until February 2028. Aerotech reported that the pilot had been tested in accordance with the DAMP prior to commencing employment. The record of this test was no longer available, as per their DAMP, the operator was not required to retain records older than 5 years. The pilot had not been tested since commencing employment as there were no circumstances that triggered a need to do so.

Safety analysis

Flight under powerlines

For the conduct of aerial application flights in the proximity of powerlines, the variation of locations and powerlines means there was no prescriptive rule for pilots to fly over or under powerlines. Guidance was provided by the operator’s Standard Operations Manual for Application Operations and the Aerial Application Pilot’s Manual, however, the decision was left to the individual pilot. Both manuals indicated that it could sometimes be safer to fly under powerlines, and that should not be undertaken without a careful consideration of the field(s) to be sprayed. This should include a visual inspection of the powerlines and surrounding area prior to commencing spraying.

The pilot had been provided the locations of powerlines via a work order. The recorded data showed that the pilot had flown in proximity to the powerlines, which was consistent with conducting a visual inspection prior to spraying. 

The data also showed that the pilot had safely managed the application flights earlier that day, with no indication of any handling issues in the vicinity of powerlines and poles. However, leading up to the accident, the pilot’s spray passes were near intersecting powerlines. The angle of intersection meant that with each successive pass, the distance between the 2 powerlines became shorter. Furthermore, not every pass had a pole located directly on the intended pass track. On the accident spray pass, the distance between the 2 powerlines had reduced to 240 m and the pole was directly in line with the pass.

On approaching the first powerline, there was no change in height, and the aircraft was flown under the powerline. After passing this powerline, the data showed a distinct direction change to the right with no indication of a climb. This may suggest that the pilot had intended to fly under both powerlines while attempting to avoid the pole by diverting right of the spray track. The ATSB also considered whether the pilot may have lost awareness of the pole, which may have necessitated the divergence to the right. However, there was insufficient evidence to confirm either scenario.

Given the proximity of the powerlines and the pole, flying under the powerlines resulted in reduced distance and time in which to safely manoeuvre the aircraft and maintain safe separation from the hazards.

Loss of control 

At previous locations where the pilot encountered a pole, the aircraft was not heading directly to the pole. The recorded data showed that the aircraft only diverged by about 7 m, sufficient to ensure clearance from the pole. However, on the accident pass, the pole was directly in front of the aircraft and required a larger divergence to ensure clearance. Due to the reduced distance/time between the 2 powerlines, the pilot appeared to have required much larger flight control inputs to avoid the pole, as evidenced by the data displaying significantly greater track divergence. 

From the analysis of the crop/ground markings, the aircraft was in a right yaw/skid and right roll attitude as the pilot attempted to avoid the pole directly on track. As the aircraft was flying very close to the crop, the manoeuvre resulted in the right wheel, right spray boom, right aileron and right wing tip being lowered to the extent that they contacted the crop and ground, reducing the aircraft’s speed. However, the aircraft was still flying towards the converging powerline and it was likely that the pilot applied left aileron to not only pick the right wing up from the crop but also lower the left wing to ensure clearance with the second powerline.

This led to a cross-control situation, where opposite aileron was required to maintain wings level while using rudder to change direction to the right. 

After avoiding the pole and passing under both powerlines, the crop markings indicated that the aircraft remained in a crossed control state and was pitched up to climb away from the crop. The aircraft pitch up was likely sufficient to increase the angle of attack above the critical angle of attack, resulting in an aerodynamic stall. Due to the crossed control state, it was likely that the right wing stalled first, resulting in the aircraft rolling inverted, at a height from which recovery was not possible.

Drug and alcohol management

Aerotech’s drug and alcohol management plan (DAMP) required that staff conducting safety sensitive aviation activities undertake DAMP education and be subject to testing. DAMP testing was conducted prior to commencing employment, post-accident or serious incident, on reasonable suspicion or after returning from substance‑related cessation of employment. Aerotech advised that the pilot had completed the required DAMP training. Since pre-employment testing, the pilot had not been subject to any DAMP testing conditions in the 5 years prior to the accident.

The pilot’s post-mortem examination and toxicology detected the presence of cocaine metabolites and a forensic pharmacologist determined that it was likely that the pilot had consumed cocaine within 24 hours prior to the accident. However, the forensic pharmacologist stated it was unlikely that the pilot was acutely intoxicated during the accident flight.

One witness recalled that the pilot appeared okay in the morning but withdrawn on the afternoon of the accident. Additionally, the pilot’s partner recalled that the pilot appeared their normal self on the morning of the accident. It was not possible to determine from toxicology evidence nor witness recollections if the pilot was experiencing any acute withdrawal phase effects of cocaine use, and these effects are known to vary between individuals.

It was not possible to determine whether the pilot’s use of cocaine contributed to the accident. However, illicit substances pose a significant risk to users as they are uncontrolled and the quality, composition and dosage of the substance cannot be guaranteed. Therefore, the actual effects cannot be known to a user, nor can a user accurately assess the ongoing effects of the substance on their ability to safely conduct a flight.

Findings

From the evidence available, the following findings are made with respect to the collision with terrain involving Air Tractor AT-802, VH-ODX, 17 km north of Cummins Town aerodrome, South Australia, on 8 September 2025.

Contributing factors

• On each new spray pass, the gap between the 2 intersecting powerlines became progressively smaller, with the accident pass decreasing to 240 m. This reduced the distance and time available for the pilot to safely manoeuvre the aircraft beneath the wires and avoid the power pole directly on track. 
• After passing beneath the first powerline, the pilot manoeuvred to avoid the pole directly ahead, during which the aircraft contacted the crop and ground. After passing beneath the second powerline, the aircraft pitched up while in a right skid and left roll. The aircraft then aerodynamically stalled and rolled inverted at a height from which recovery was not possible.

Other factors that increased risk

• It was likely the pilot used cocaine within 24 hours prior to the accident.  While the pilot was unlikely to have been directly affected by the drug at the time of the accident, the actual effect of illicit substances on the safety of flight cannot be predicted by users, and periods of impairment beyond the anticipated effects can occur.

Safety actions

Safety action by Aerotech Australasia Pty Ltd

Aerotech advised the ATSB that it has taken the following safety action. 

After consultation with its pilot group, Aerotech amended its operations manual to include guidance on paddock inspections, hazard marking, treatment of paddocks containing wires, operating parameters around wires, undulating terrain and other ground-based obstacles. The operator also advised this would have ongoing refinement through the safety management system and pilot feedback.

The aircraft fleet was being configured with the latest Tabula GPS systems. Paddocks would be assigned to the aircraft before departure rather than identified visually from a printed map. Wires, towers, weather stations and other hazards were to be marked, with hazard alerting. Guidance on its use was included in the operations manual.

Aerotech has further developed its risk register, which is being actively managed by the safety manager. This included periodic verification of risk controls and review when an event was reported. 

Aerotech has also implemented a human factors and non-technical skills program, which was a practical training and discussion program drawing on pilot experience, lessons learnt and case studies. It incorporated a ‘Safety II’ approach, identifying and reinforcing what was being done well alongside traditional hazard identification. A post-season debrief with pilots and ground crew forms part of the program.

Sources and submissions

Sources of information

The sources of information during the investigation included:

• Aerotech Australasia Pty Ltd
• the maintenance organisation for VH-ODX
• recorded data from the avionics units on the aircraft
• the manufacturer of the Tabula system on the aircraft
• next of kin of the pilot
• Civil Aviation Safety Authority
• South Australia Police
• South Australia Coroner.

References

Aerial Agricultural Association of Australia. (2011). Aerial Application Pilots Manual 3rd Edition. Australian Capital Territory: Aerial Agricultural Association of Australia.

Dawson, D., & McCulloch, K. (2005). Managing fatigue: it's about sleep. Sleep medicine reviews, 9(5), 365-380.

Isenschmid, D. S. (2002). Cocaine - Effects on Human Performance and Behavior. Forensic Sci Rev, 14(1-2), 61-100.

United States Federal Aviation Administration. (2021). Airplane Flying Handbook (FAA-H-8083-3C). United States: Federal Aviation Administration.

Watson, N. F., Badr, M. S., Belenky, G., Bliwise, D. L., Buxton, O. M., Buysse, D., ... & Heald, J. L. (2015). Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Journal of Clinical Sleep Medicine, 11(6), 591-592.

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:

• Aerotech Australasia Pty Ltd
• Civil Aviation Safety Authority
• National Transportation Safety Board
• Transportation Safety Board of Canada.

A submission was received from Aerotech Australasia Pty Ltd. The submission was reviewed and, where considered appropriate, the text of the report was amended accordingly.

Purpose of safety investigations The objective of an ATSB safety investigation is to improve transport safety through: identifying safety issues for action by organisations with the responsibility for managing that safety risk influencing safety action through engaging with stakeholders, communicating findings, and fostering awareness of safety issues and concerns.  In accordance with the TSI Act, the ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action, and cannot apportion blame, assist in determining liability, or, as a general rule, assist in court proceedings.  About ATSB reports ATSB safety investigation reports are developed in accordance with ATSB procedures and guidelines, and with regard to applicable international standards and instruments. Reports must include factual material of sufficient weight to support the investigation’s 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. An explanation of terminology used in ATSB investigation reports is available here.   Publishing information Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2026 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 Commonwealth Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this report is licensed under a Creative Commons Attribution 4.0 International licence. The  CC BY 4.0 licence enables you to distribute, remix, adapt, and build upon our material in any medium or format, so long as attribution is given to the 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 conducted under Part 137 of the Civil Aviation Safety Regulations (aerial application operations).
2. ^    Loader: the term used to denote ground support personnel whose functions include assisting with mixing chemicals, loading and dispatching the aircraft.
3. ^    Racetrack pattern: the application pattern that involves making successive overlapping loops across a field.
4. ^    Pilots delay the commencement of spraying and prematurely shut off spraying at the end of a field to ensure the chemical does not get applied to an adjacent field. A clean‑up run is a spray pass perpendicular to the predominant direction along the edge of a field to ensure crop near that fence line has appropriate coverage.
5. ^    Civil Aviation Safety Authority exemption EX28/23, in effect at the time of the accident, exempted the pilot from needing to hold a class 1 aviation medical certificate for aerial application flights such as the accident flight. The exemption was subject to the pilot holding a class 2 medical certificate.
6. ^    Passes 1, 3, 5, 7 and 9 were flown in an easterly direction. They were not examined in detail as they were south of passes 2, 4, 6, 8, 10 and not in conflict with the same powerlines.    
7. ^    The aircraft’s height was as recorded by the onboard GPS, and not a barometric height.
8. ^    The aircraft’s indicated airspeed was not able to be determined as there was insufficient information available to accurately calculate. Based on the reported conditions at the supply airstrip, the ATSB estimated that the groundspeed was closely approximate to indicated airspeed.
9. ^    The United States Federal Aviation Administration defines a skid as a condition where the tail of the airplane follows a path outside the path of the nose during a turn. It is an example of uncoordinated flight where the aircraft nose is yawing to the inside of a turn.
10. ^   The angle the wing makes with the local horizontal. 
11. ^   Carbon monoxide is a colourless, odourless and tasteless gas found in the exhaust gases of piston‑engine aircraft.

Investigation summary

What happened

On 22 August 2025, a GippsAero GA8, operated by Air Kimberley and registered VH‑LHC, entered the circuit in preparation for landing at Djarindjin/Lombadina Airport, Western Australia. At about this time, the pilot identified an uncommanded 3-inch drop in engine manifold pressure. After briefly liaising with the chief pilot via phone, the pilot conducted an orbit between the base and final legs of the circuit to prepare for the landing. 

Crossing the threshold, the pilot identified that they were between 20 and 25 kt above the target approach speed. Approximately two-thirds of the way down the runway, the pilot assessed there was insufficient runway remaining to land, commenced a go-around and attempted to climb away. However, the airspeed reduced and the pilot assessed that they did not have sufficient power to climb and elected to level the aircraft and conduct a turnback to land on the reciprocal runway. The pilot used the mixture control to reduce the engine’s power and landed without further incident.  

What the ATSB found

During the approach, the securing mechanism for the aircraft’s throttle linkage failed, resulting in a loss of throttle control and a constant partial power setting. The approach then continued at a higher-than-normal speed that did not permit the aircraft to land safely.

During the subsequent go-around, the pilot assessed there was insufficient power to climb. This was due to the throttle failing to open to at least 75% in accordance with the manufacturer’s requirement, likely due to the spring that opened the throttle in the event of a disconnection not being fitted.

Additionally, the ATSB found that there were multiple inconsistencies between the throttle linkage hardware fitted to VH-LHC and that laid out in the aircraft documentation. Although the ATSB could not determine whether the inconsistencies contributed to this incident, they increased the risk of throttle disconnection due to unintended interactions between components in the linkage. 

What has been done as a result

In response to the ATSB advice noting the inconsistencies between the linkage assembly and the manufacturer’s prescribed configuration, the maintenance organisation, BOAB Engineering (BOAB), conducted a review of the 3 GA8 aircraft that it was responsible for. 

BOAB identified various inconsistencies related to incorrect throttle body lever arms, missing torsion springs and incorrectly located or missing spacers. At the time of writing, BOAB advised that the correct parts had been ordered and that the linkage assemblies would be re-assembled in accordance with the manufacturer’s requirements.

Safety message

Partial power loss can be more complex to manage than a complete power loss. The response to a complete power loss is definitive and standardised but the response to a partial power loss may be dependent on the amount of power lost and reliability of the remaining power. CASA's guidance is to treat a partial power loss as though it is a complete power loss and to ensure that the aircraft is landed as soon as possible. Where engine power is available pilots can consider using it to extend available flight time to identify a better landing site with the awareness that the power may reduce or fail at any time. 

This occurrence also demonstrates the importance of being aware of and adhering to the manufacturer’s assembly requirements. Reconnecting a component’s attachment hardware on a like-for-like basis may not ensure compliance with the manufacturer’s requirements and can increase the risk of an adverse outcome.   

The investigation

The occurrence

On the morning of 22 August 2025, a GippsAero GA8, operated by Air Kimberley and registered VH‑LHC, departed Broome, Western Australia, for a charter flight to Djarindjin/Lombadina Airport (Figure 1) with the pilot, one passenger and freight on board. 

Figure 1: VH-LHC flight location

Source: Google Earth and FlightRadar24, annotated by the ATSB

Approximately 55 minutes after departing Broome, the pilot joined the downwind leg of the circuit for runway 28 at Djarindjin/Lombadina Airport. Shortly after joining the circuit, at about 1251 local time, the pilot identified an uncommanded 10 kt reduction in airspeed and a drop from approximately 20 inches of mercury (inHg) of engine manifold pressure to 17 inHg. In response, the pilot moved the aircraft throttle lever across its full range of movement but did not hear or feel a response from the engine and reported no change to the manifold pressure. 

At this time, the pilot contacted the operator’s chief pilot via mobile phone for guidance. The pilot reported that in the brief conversation they outlined the issue that they were encountering. While the pilot could not remember the details of the chief pilot’s response the general guidance provided was to land as safely as possible and to call back when they were on the ground. 

Following this conversation, the pilot elected to conduct an orbit to extend the approach (Figure 2) and allow themselves more time to assess the problem and conduct pre‑landing checks and procedures. They intended to conduct the approach normally but with an extended final approach. The pilot also considered the early use of a second stage of flap to slow the aircraft. However, they decided against it due to the unknown reliability of the engine’s performance and extended the second stage of flap as part of the normal pre-landing process on final approach.    

Figure 2: Downwind, final approach, go‑around and return

Note: Due to the light and variable winds at the time of the occurrence, the aircraft ground speeds were within 5 kt of the airspeeds that would have been presented to the pilot. Source: Google Earth, FlightRadar24 and Bureau of Meteorology, annotated by the ATSB

The pilot recalled, and recorded data confirmed, that the aircraft was at about 100 kt, 20‍–‍25 kt faster than planned, when crossing the threshold. Approximately two-thirds of the way down the runway, the pilot identified that the aircraft was ‘floating,’¹ had insufficient runway remaining to land the aircraft, and elected to conduct a go-around. The pilot initiated a climb, retracted one stage of flap and felt the airspeed start to reduce from 84 kt at the time the go‑around was initiated, to 68 kt as they turned off the runway heading. The pilot reported reaching approximately 300 ft above ground level, assessed that there was insufficient performance to safely continue the climb and levelled the aircraft. 

The pilot’s planned forced landing option when taking off from runway 28 at Djarindjin/Lombadina was a beach on the western side of scrubland beyond the end of the runway (Figure 2). However, the pilot assessed that this was not suitable and subsequently turned to the left for a return to runway 28. 

During the turn, the aircraft maintained altitude and accelerated from 68 to 88 kt. The pilot reported that, after the turn, they were unsure if the engine would continue producing power long enough to complete a circuit. They subsequently decided to land on runway 10, the reciprocal runway. Having determined that they were able to reduce the engine’s power using the mixture control, the pilot brought the mixture to near the cut‑off position and conducted a turnback to runway 10, slowing the aircraft through 75 kt to 70 kt before landing. 

After landing, the pilot increased engine power by returning the mixture to rich and taxied off the runway. Subsequently, after consultation with the company’s maintenance provider, it was determined that the throttle linkage had disconnected at the engine. 

Context

Pilot information

The pilot held a Commercial Pilot Licence (Aeroplane) with a command instrument rating and a valid class 1 aviation medical certificate. The pilot reported that at the time of the occurrence they had 869 hours of total aeronautical experience with 385 of these being on the GA8 and 48 in the last 90 days. 

Operational information

Emergency procedures

The GA8 pilot’s operating handbook contained relevant procedures for the operation of the aircraft in the event of an emergency. The manual did not contain a specific procedure for the management of partial power, however there were procedures for both a precautionary landing with engine power and an emergency landing without engine power. 

The procedure for a precautionary landing with power included an indicated airspeed of 75 kt on approach with stage 1 flap extended. The procedure for landing without engine power included an indicated airspeed on final approach of between 64 and 71 kt depending on aircraft weight. In normal operation the approach speed was 71 kt.

The procedure for landing without engine power required the pilot to switch off the ignition, fuel shutoff valve, and the master electrical buses, to move the throttle to the closed position, the mixture to the idle cut off position and the propellor to coarse. 

The procedure for a precautionary landing with power required the mixture to be moved to the idle cut‑off position and the ignition, fuel shut‑off valve and bus 1 and 2 master switches to be moved to the off position after touchdown.  

Management of partial power loss

Management of a partial power loss is more complex than a complete power loss. The response to a complete power loss should be definitive and standardised while the number of factors that could lead to a partial power loss and the unreliability of any remaining power meant that a situationally specific response is required. 

While the manufacturer did not provide guidance on the management of partial power loss in the GA8, both the Civil Aviation Safety Authority (CASA) and the ATSB have published general guidance on the subject – CASA in its flight instructor manual and the ATSB in Managing partial power loss after takeoff in single-engine aircraft (AR-2010-055 - Number 3). The guidance contains 3 key points:

• a partial power loss event should be treated like a complete power loss and a landing should be conducted as soon as possible
• any available power may be used to extend the flight time to locate a better landing area
• this should be done with the consideration that the power may degrade further or be lost at any time.

Throttle operation

The GA8 flight manual advised that a normally aspirated engine had a manifold pressure range between 10 and 30 inHg. However, the range available for use was dependent on the altitude at which the aircraft was operating.

The pilot stated that when approaching Djarindjin/Lombadina on descent they typically set 20 inHg, reducing this to 18 inHg passing the threshold during the downwind leg of the circuit and then to 15 inHg when making the turn onto the base leg.

Meteorological information

An aerodrome meteorological report for Djarindjin/Lombadina was issued at 1300 local time, approximately 5 minutes after VH-LHC crossed the threshold on its first approach. The wind recorded was from 050° at 4 kt with 9,000 meters visibility, temperature 30°C and no recorded rainfall.

One-minute wind observations between 1250 and 1300 showed variable wind direction at 2‍–‍5 kt. 

Aircraft information

General information

The GA8 is a single‑engine aircraft manufactured by GippsAero² of Victoria, Australia. It is fitted with a Textron Lycoming IO-540-K1A5 piston engine and can seat up to 8 people, including the pilot. VH-LHC (serial number GA8-04-057) was manufactured and registered in 2004. At the time of the occurrence, it had accumulated 11,768 hours total time in service. For this flight, the aircraft was configured for a single passenger next to the pilot and with the rear passenger seats removed and appropriate securing equipment in place for carriage of freight. 

Throttle cable attachment assembly

The throttle cable assembly translated movement of the throttle lever in the cockpit to the throttle body on the engine. The throttle body attachment consisted of a rod end and throttle body lever arm bolted together with a series of washers and spacers used to ensure appropriate geometry was maintained. The geometry of the washers and spacers allowed both the rod end and throttle body lever arm to move freely and limited interaction with the other components. If the geometry was not correctly maintained, the rod end could forcefully contact the penny washer and, as the rod end moved through its arc of motion, induce a rotation in the penny washer and subsequently, in the bolt. This interaction could result in a loosening or disconnection of the linkage.

Figure 3 shows the exploded diagram of the linkage from the aircraft manufacturer’s illustrated parts catalogue (IPC) and an exemplar assembly provided by the manufacturer.

Figure 3: Throttle cable attachment assembly

Source: Manufacturer, modified and annotated by the ATSB

The threaded end of the bolt specified in the IPC (AN3-11) is drilled allowing a split pin to be used as a secondary securing mechanism. However, the specified nut (MS21042-3) is a reduced hex nut that uses interference with an out of round section to lock the nut onto the bolt and consequently does not require a split pin. This combination, while permitted and approved, was not commonly used as a reduced hex nut is typically used in combination with a non-drilled bolt. When consulted, the manufacturer could not advise why this hardware combination had been prescribed for the aircraft. However, they advised that some elements of the design for this aircraft had been reproduced from the design of another aircraft, including the specified bolt. 

The throttle body lever arm on the GA8 was developed by GippsAero by modifying the design of the standard arm supplied by the engine manufacturer. The modification made the arm approximately 12 mm shorter than when used for other applications with the same engine. This modification altered the arc through which the arm moved to ensure that the geometry between the throttle cable and the throttle body was correct. The manufacturer’s review of the images of VH-LHC’s throttle arm identified that a standard lever arm was fitted rather than the GippsAero lever arm. 

Figure 4 shows the throttle lever arm as fitted to VH-LHC in comparison to an exemplar of the shortened lever arm as prescribed for the aircraft by GippsAero in the IPC. Note the throttle positions shown in the images are not the same and the image has been rotated to show the difference in length between the lever arms.

Figure 4: Throttle lever arm comparison

Source: Operator and aircraft manufacturer, modified and annotated by the ATSB

Spring‑loaded mechanism

The certification standard for the GA8 required that if the engine control separated, it must be designed so that the aircraft is capable of ‘continued safe flight and landing’. This requirement was implemented by the United States Federal Aviation Administration (FAA) in response to a 1981 National Transportation Safety Board (NTSB) study of single‑engine aircraft accidents involving separation of throttle linkages and subsequent loss of propulsive power. The NTSB recommendation (A-81-6) to the FAA was to: 

Establish a requirement that, when throttle linkage separation occurs in a small single engine aircraft the fuel control will go to a setting which will allow the pilot to maintain level flight in the cruise configuration; (Class 11, Priority Action) 

In response, the FAA introduced a requirement under regulation 23.1147(g) that: 

For reciprocating single-engine airplanes, each power or thrust control must be designed so that if the control separates at the engine fuel metering device, the airplane is capable of continued safe flight and landing

For the GA8 to comply with this requirement, the throttle body linkage was fitted with a torsion spring with sufficient tension to drive the throttle to at least 75% of the full throttle setting. The torsion spring is mounted directly to the throttle body as shown in Figure 5 and can subsequently drive the throttle to the required position in the event of a disconnection anywhere along the throttle linkage.

Figure 5: Spring location

Source: Manufacturer, modified and annotated by the ATSB

In 2011, GippsAero published service bulletin SB-GA8-2011-64 in response to reports of throttles failing to open sufficiently. The service bulletin required that spring tension be tested and if it was not able to open the throttle sufficiently, a stiffer spring was required to be installed. This service bulletin was completed on VH-LHC on 28 February 2011 at 5,150.5 hours. 

Post‑occurrence examination

The ATSB was provided with an image taken by the pilot immediately after the occurrence (Figure 6). It shows the throttle body lever arm at approximately 25% travel with the through bolt from the rod end disconnected from the lever arm. Only the bolt and penny washer from the cable attachment assembly were visible in the image. The remaining components including the nut, washer and spacers were unable to be identified.

Figure 6: Post‑occurrence image of throttle body and throttle cable attachment assembly

Source: Operator, annotated by the ATSB

Following reconnection of the linkage using new hardware, the ATSB requested the nut and bolt from the maintainers, however they were unable to provide either. They reported that the nut was not recovered during the repair and the bolt could not be located. The maintainers reported that damage to the bolt threads was identified when it was removed.

A subsequent review of the IPC identified that the correct securing mechanism was a reduced hex nut and not the castellated nut and split pin that had been fitted during the repair (see the section titled Engine change for further information).

Following the occurrence, the ATSB and the manufacturer reviewed the available imagery. The manufacturer stated that the imagery appeared to show an incorrect configuration of the throttle cable attachment assembly, with markings on the end of the throttle body lever arm indicating that at least one of the spacers had been incorrectly located. The ATSB also identified, and the manufacturer confirmed, that the spring on the throttle mechanism was missing (Figure 7). 

Figure 7: Post‑occurrence imagery identifying location of throttle mechanism spring

Source: Operator and manufacturer, annotated by the ATSB

Maintenance information

Engine change

In June 2025, VH-LHC’s engine was removed due to detonation damage. The engine including the frame and ancillary components, such as hoses and baffles, were removed and a serviceable engine and propeller from another GA8 were installed. The aircraft was released back into service on 3 June 2025. The maintainer who conducted the engine change was contracting to the maintenance organisation and had not previously (and did not subsequently) work on this aircraft. 

They reported that when they disconnected the linkage there were thick section washers fitted to either side of the rod end, a penny washer under the bolt and the linkage was secured with a castellated nut and split pin. They reported reusing the hardware from the removed engine with a new split pin and that their post‑installation checks identified no issues with the movement of the throttle.

The maintainer stated that, based on their experience and the presence of the hole in the bolt, the use of a castellated nut and split pin was logical, and they did not refer to the aircraft documentation to confirm the hardware configuration. 

Related occurrences

A review of the ATSB’s occurrence database did not identify any similar occurrences, however the manufacturer identified a continuing airworthiness notice (CAN) issued in 2007 by the New Zealand Civil Aviation Authority (CAA) related to a similar issue and a review of the CASA defect reporting database identified a similar issue from an aircraft in Botswana in 2017.

New Zealand Civil Aviation Authority Continuing Airworthiness Notice 76‑001

On 5 July 2007, the NZ CAA released a CAN on all GA8 aircraft for an inspection of the throttle cable and the throttle lever installation. A CAA investigation had been prompted by reports of a sluggish feel in the throttle operation of a GA8. The investigation identified that the linkage bolt was rotating, resulting in a loosening of the nut securing the mechanism. Contact between the penny washer and the rod end resulted in movement of the rod end causing the penny washer, and subsequently the bolt, to rotate. 

As published, the CAN contained a recommendation for an updated configuration of the linkage assembly intended to increase the approach angle between the penny washer and the rod end. In February 2026, the CAA advised that the manufacturer’s configuration addressed the issue and subsequently the CAN had been removed from the NZ CAA website. In response to the draft ATSB report, the CAA advised that the CAN was pending revision and reissue, following the release of the ATSB report.

Figure 8 compares the reconnected linkage configuration on VH-LHC (left) with the manufacturer’s exemplar configuration (right). The spacers shown in the manufacturer’s configuration provide increased clearance between the penny washer, rod end and the throttle body lever arm compared to the washers used in the reconnected configuration. 

Figure 8: Throttle linkage assembly comparison

Source: Operator and manufacturer, annotated by the ATSB

The pre-occurrence configuration of the linkage fitted to VH-LHC was unable to be determined. However, the reconnected configuration showed a limited clearance between the rod end and the penny washer due to the missing spacers. This lack of clearance meant that the rod end was likely to contact the penny washer when the throttle was moved through the full range of motion. 

As identified by the CAA’s investigation, this creates a risk of interaction between these parts and potential for loosening and disconnection of the linkage. In comparison, the spacers used in the manufacturer’s configuration separate the rod end from the penny washer to prevent interaction. 

CASA defect report

A review of the CASA defect reporting database identified a report from 8 May 2017 related to aircraft A2-FTW,³ as follows:

Loosened nut and insecure throttle control cable rod-end and bolt discovered, caused by engine vibration.

New nut installed and tightly secured to the throttle control linkage on fuel injector.

Safety analysis

Approach

The pilot reported that the flight to Djarindjin/Lombadina was uneventful until the aircraft entered the circuit. During the downwind leg of the circuit, the pilot observed an uncommanded drop in manifold pressure from 20 to 17 inHg and was no longer able to control engine power using the throttle lever. Once the pilot made the base turn, the 17 inHg manifold pressure was above the 15 inHg setting they would have typically been using. Imagery of the throttle linkage captured by the pilot following the occurrence showed the linkage disconnected and the securing nut missing with the throttle arm near to, but not at, the idle position. The consequence of the linkage disconnection was that movement of the throttle lever in the cockpit could not be translated to the throttle lever arm on the engine resulting in a loss of throttle control. 

As the approach progressed, the pilot reported, and recorded data showed, that the aircraft was 20–25 kt above the recommended approach speed of 75 kt as it crossed the threshold. At that speed, the pilot assessed that there was insufficient runway available to slow the aircraft and make a safe landing.

Go-around

After the pilot identified that there was insufficient runway remaining to land safely, they commenced a go-around and the aircraft’s speed immediately started to reduce. The pilot reported that the aircraft was correctly configured for climb with one stage of flap, propeller pitch at full fine and that other than the limited power there were no issues that should have adversely affected climb performance. Unable to use the throttle to increase the power from the engine, the aircraft continued to slow, and so the pilot levelled the aircraft. The pilot then commenced a left turn and the engine was producing sufficient power for the aircraft to accelerate through the turn while maintaining altitude. 

Aircraft certification standards required that, in the event of a throttle linkage disconnect, the engine side of the throttle linkage move to a position that would enable ‘continued safe flight and landing’. The manufacturer therefore required that a torsion spring be installed on the throttle linkage that would open the throttle to at least 75% of the open position in the event of a disconnection. 

The image captured by the pilot immediately following the occurrence showed the throttle in a low power position, well below the 75% open position that was required by the manufacturer. Due to the number of factors that can impact the relationship between throttle position and observed manifold pressure, it was not possible to determine what the manifold pressure should have been if the throttle was open to 75%. However, as available power increases as the throttle opens, the position of the throttle arm below the 75% open position meant that there was less power available than that required by the manufacturer to sustain ‘continued safe flight and landing’.

It was further identified and confirmed by the manufacturer that the torsion spring was not visible in the imagery captured immediately after the occurrence. The ATSB considered 2 possible scenarios for the missing torsion spring. The first was that the spring had been present and had failed since the last maintenance activity or during the occurrence and the second was that the spring was not fitted at the time of the engine change.

As the spring was fitted around the shaft, in the event of a failure, the spring would have been retained on the shaft and been visible. Additionally, it is very unlikely that the spring would have failed at the time of the linkage disconnection as in the event of a disconnection the tension on the spring would have been released to drive the throttle arm to at least the 75% open position.

While it could not be conclusively determined if the required torsion spring was fitted at the time of the occurrence, it was considered very likely that it was not fitted due to:

• the visible lack of the spring 
• the fact that the spring would have been retained should it have failed 
• the limited time between maintenance and the occurrence for the spring to become detached and be lost
• the fact that the throttle did not open, which is the purpose of the spring being fitted. 

Installation inconsistencies

There were several inconsistencies between the throttle linkage installation on VH-LHC and the arrangement outlined in the aircraft documentation, as follows:

• the manufacturer identified that the throttle arm fitted was not correct for the aircraft
• the maintainer reported using a castellated nut with split pin, rather than the specified reduced hex nut
• the throttle opening spring was very likely not fitted 
• the spacers were likely not fitted correctly prior to the occurrence. 

As shown by the New Zealand Civil Aviation Authority Continuing Airworthiness Notice, changes to the throttle linkage geometry can lead to undesirable interactions between components within the linkage, most notably the rod end and the penny washer. This can subsequently loosen the linkage and could result in complete disconnection. 

The ATSB could not determine whether the inconsistencies between the recommended, and actual throttle linkage configurations contributed to the disconnection. This was primarily due to limited evidence about the sequence of the disconnection but was also influenced by the limited and incomplete information about the pre-occurrence linkage configuration. The likely configuration of the throttle linkage was determined based on manufacturer review of the available imagery, the recollection of the maintainer who completed the engine installation approximately 4 months before the occurrence and imagery of the reassembled linkage following the occurrence. 

The individual impact of each of these inconsistences could not be determined.  However, the combination of the inconsistencies, and their potential impact on the geometry of the linkage and subsequent interaction between the components, increased the risk of a disconnection.

Findings

From the evidence available, the following findings are made with respect to the engine malfunction involving GippsAero GA8, VH-LHC, at Djarindjin/Lombadina Airport, Western Australia, on 22 August 2025. 

Contributing factors

• During the approach, the securing mechanism for the aircraft’s throttle linkage failed resulting in a loss of throttle control and a constant partial power setting. The approach then continued at a higher-than-normal speed that did not permit the aircraft to land safely.
• During the subsequent go-around, the pilot assessed there was insufficient power to climb. This was due to the throttle failing to open to at least 75% in accordance with the manufacturer’s requirement, likely due to the spring that opened the throttle in the event of a disconnection not being fitted. 

Other factors that increased risk

• There were multiple inconsistencies between the throttle linkage hardware fitted to VH-LHC and that laid out in the aircraft documentation. This increased the risk of throttle disconnection due to unintended interactions between components in the linkage. 

Safety actions

Safety action taken by BOAB Engineering

In response to the ATSB advice noting the inconsistencies between the linkage assembly and the manufacturer’s prescribed configuration, the maintenance organisation (BOAB) conducted a review of the 3 GA8 aircraft that it was responsible for. 

BOAB identified various inconsistencies related to incorrect throttle body lever arms, missing torsion springs and incorrectly located or missing spacers. It advised that the correct parts had been ordered and that the linkage assemblies would be re-assembled in accordance with the manufacturer’s requirements.

Sources and submissions

Sources of information

The sources of information during the investigation included:

• the pilot of the occurrence flight 
• the operator of VH-LHC
• the maintenance organisation for VH-LHC
• the maintainer who completed the engine change on VH-LHC
• GippsAero
• New Zealand Civil Aviation Authority
• Civil Aviation Safety Authority
• Bureau of Meteorology
• Flight Radar 24
• Federal Aviation Administration
• National Transportation Safety Board.

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:

• the pilot of the occurrence flight 
• the operator of VH-LHC
• the maintenance organisation for VH-LHC
• the maintainer who completed the engine change on VH-LHC
• GippsAero
• Transport Accident Investigation Commission (New Zealand)
• New Zealand Civil Aviation Authority
• Civil Aviation Safety Authority.

Submissions were received from:

• New Zealand Civil Aviation Authority
• the maintainer who completed the engine change on VH-LHC.

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. About ATSB reports ATSB investigation reports are organised with regard to international standards or instruments, as applicable, and with ATSB procedures and guidelines. Reports 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. 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 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2026 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 Commonwealth Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this report is licensed under a Creative Commons Attribution 4.0 International licence. The CC BY 4.0 licence enables you to distribute, remix, adapt, and build upon our material in any medium or format, so long as attribution is given to the 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.

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