Oceania

The following factors were identified:
- The pilot did not complete a trim sheet for the flight.
- The manifest was completed by a ground handler who was not present at the time the cargo was being loaded by other ground handlers. The manifest was not signed by the ground handler who completed it, nor was it authorized by the pilot before departure.
- Pilot’s lack of supervision of the aircraft’s loading process to ensure cargo is loaded correctly and in accordance with the prescribed limitations and to prevent calculation errors. As a result, it was likely that the aircraft was overweight when it departed.
- Wet strip surface conditions that caused significant resistance during the take-off roll and impeded the aircraft’s ability to reach its required lift off airspeed.
- Pilot’s decision to continue the take-off roll after passing the committal.
- Training deficiencies of ground handlers and the pilot.
- The lack of adequate Quality Assurance systems oversight on the operator’s operating standard procedures.

The ATSB found that the accident drop was conducted at a low height and airspeed downhill, which required the use of idle thrust and a high descent rate. The delay in the engines reaching go-around thrust at the end of the drop resulted in the aircraft’s height and airspeed (energy state) decaying as it approached rising terrain, which was not expected or detected by the pilot flying. Consequently, the aircraft’s airspeed and thrust were insufficient to climb above a ridgeline in the exit path, which resulted in a controlled flight into terrain. The operator’s practice of recalculating, and lowering, their target drop speed after a partial load drop also contributed to the low energy state of the aircraft leading up to the collision with terrain.
The ATSB also found that the operator and tasking agency had not published a minimum drop height, which resulted in the copilot, who did not believe there was a minimum drop height, not making any announcements about the low energy state prior to the collision. The ATSB found the operator’s pilot monitoring duties were reactive to the development of a low energy state and did
not include call-outs either before or at the minimum target parameters to reduce the risk of a low energy state developing.
The ATSB benchmarked the WA, New South Wales and National Aerial Firefighting Centre standards against the United States Forest Service and United States National Wildfire Coordinating Group standards and found inconsistencies between the Australian agencies’ standards but not among the United States agencies’ standards. This was likely a result of each Australian state participating in the LAT program independently producing their own standards.

The ATSB found that the dual engine speed fluctuations and associated power loss was probably the result of fuel starvation. The mechanism was not conclusively determined, however it was identified that the pilot did not operate the aircraft's fuel system in accordance with the aircraft flight manual, and that the configuration and location of the aircraft’s fuel controls and tank quantity gauges were probably not conducive to rapid and accurate interpretation. The aircraft manufacturer released a service letter in June 2022 that detailed an optional modification to centralize the fuel system controls and gauges, however this modification was not fitted to VH-WQA. The ATSB considered that these factors increased the risk of inadvertent fuel tank selection.

During the landing at Tekin Airstrip, the pilot encountered downdraft and touchdown about 4 metres short of the designated landing threshold. Due to less damping effect on the oleo or the tyre, the landing impact force could have transferred up through the structure and concurrently causing the left main landing gear to collapse. Subsequently, the left wing abruptly dropped and began veering to the left, towards the eastern edge of the airstrip. The aircraft continued veering to the left and subsequently the left wingtip struck the outer edge of the extended right-side flap of P2-BWE, causing it to abruptly veer further left and skid across the airstrip boundary as the nose-wheel and right main wheel bogged into the ground.

The investigation identified that during touchdown, the aircraft’s main landing gear tyre hit the 15cm elevation at the edge of runway18, resulting in the left MLG assembly weakening. The investigation determined that due to less damping effect on the oleo or the tyre, the landing impact force could have transferred up through the structure and concurrently causing the left MLG assembly to collapse. Following the collapse of the left MLG assembly, the left-wing assembly dropped and hit the ground, the flap detached and began to drag on the surface of the strip creating markings. The aircraft immediately began veering left, towards the edge (boundary) of the airstrip and impacted the drainage ditch adjacent to the runway where it came to rest.

The investigation determined that the separation of the outboard section of the left wing, clipped by a tree during the approach to land phase, affected the ability of the left wing to produce lift. The investigation could not conclusively determine the actual weight and balance of the aircraft as it was not possible to determine the quantity and quality of fuel on board, nor the weight and distribution of the cargo that was on board. The evidence gathered during the investigation did not allow the AIC to discard overweight, balance or centre of gravity issues due to improper loading or restrain of the cargo as factors contributing to the inability of the aircraft to obtain a positive rate of climb during take-off. The evidence of tire marks found by the investigators on the uncommissioned field indicated that the aircraft touched down about 400 m before the end of the field, distance that was not enough for the aircraft to come to a stop, continuing its landing roll into the bushes and impacting trees until it got to its final position. The investigation determined that the aircraft was not airworthy at the time of the accident and was unserviceable for the conduct of the flight. The investigation also determined that there was no proper document control to conduct timely scheduled maintenance and that there was no record of a certificate of airworthiness (CoA) at the time of the accident.

The following findings were identified:
- The pilot did not make the necessary left turn during the take-off roll to align with the strip centreline, so the aeroplane continued the take-off roll in a straight line.
- The right-rear undercarriage struck uneven ground with sufficient force to break the undercarriage mounting brackets and dislodge the undercarriage assembly from the aeroplane.
- The right main undercarriage subsequently struck the right flap, resulting in a partial dislocation of the flap. This very likely resulted in the aeroplane becoming uncontrollable.
- The pilot was about as likely as not to have been incapacitated early in the take-off roll.

The accident was the consequence of a controlled flight into terrain.
The following contributing factors were identified:
• While the pilot was operating in the vicinity of Lockhart River Airport, there were areas of cloud and rain that significantly reduced visibility and increased the risk of controlled flight into terrain.
In particular, the aircraft probably entered areas of significantly reduced visibility during the second approach.
• After an area navigation (RNAV) global satellite system (GNSS) approach to runway 30 and missed approach, the pilot immediately conducted another approach to the same runway that was on a similar gradient to the recommended descent profile but displaced about 1,000 ft below that profile. While continuing on this descent profile, the aircraft descended below a segment minimum safe altitude and the minimum descent altitude, then kept descending until the collision with terrain about 6 km before the runway threshold.
• Although the exact reasons for the aircraft being significantly below the recommended descent profile and the continued descent below the minimum descent altitude could not be determined, it was evident that the pilot did not effectively monitor the aircraft’s altitude and descent rate for an extended period.
• When passing the final approach fix (FAF), the aircraft’s lateral position was at about full-scale deflection on the course deviation indicator (CDI), and it then exceeded full-scale deflection for
an extended period. In accordance with the operator’s stabilized approach procedures, a missed approach should have been conducted if the aircraft exceeded half full-scale deflection at the FAF, however a missed approach was not conducted.
• The pilot was probably experiencing a very high workload during periods of the second approach. In addition to the normal high workload associated with a single pilot hand flying an approach in instrument meteorological conditions, the pilot’s workload was elevated due to conducting an immediate entry into the second approach, conducting the approach in a different manner to their normal method, the need to correct lateral tracking deviations throughout the approach, and higher than appropriate speeds in the final approach segment.
• The aircraft was not fitted with a terrain avoidance and warning system (TAWS). Such a system would have provided visual and aural alerts to the pilot of the approaching terrain for an extended period, reducing the risk of controlled flight into terrain.
• Although the aircraft was fitted with a GPS/navigational system suitable for an area navigation (RNAV) global satellite system (GNSS) approach and other non-precision approaches, it was not fitted with a system that provided vertical guidance information, which would have explicitly indicated that the aircraft was well below the recommended descent profile. Although the operator had specified a flight profile for a straight-in approaches and stabilized approach criteria in its operations manual, and encouraged the use of stabilized approaches, there were limitations with the design of these procedures. In addition, there were limitations with other risk controls for minimizing the risk of controlled flight into terrain (CFIT), including no procedures or guidance for the use of the terrain awareness function on the aircraft’s GNS 430W GPS/navigational units and limited monitoring of the conduct of line operations.

Other factors that increased risk:
• Although an applicable height of 1,000 ft for stabilized approach criteria in instrument meteorological conditions has been widely recommended by organizations such as the International Civil Aviation Organization for over 20 years, the Civil Aviation Safety Authority had not provided formal guidance information to Australian operators regarding the content of stabilized approach criteria. (Safety issue)
• The Australian requirements for installing a terrain avoidance and warning system (TAWS) were less than those of other comparable countries for some types of small aeroplanes conducting air transport operations, and the requirements were not consistent with International Civil Aviation Organization (ICAO) standards and recommended practices. More specifically, although there was a TAWS requirement in Australia for turbine-engine aeroplanes carrying 10 or more passengers under the instrument flight rules:
- There was no requirement for piston-engine aeroplanes to be fitted with a TAWS, even though this was an ICAO standard for such aeroplanes authorized to carry 10 or more passengers, and this standard had been adopted as a requirement in many comparable countries.
- There was no requirement for turbine-engine aeroplanes authorized to carry 6–9 passengers to be fitted with a TAWS, even though this had been an ICAO recommended practice since 2007, and this recommended practice had been adopted as a requirement in many comparable countries. (Safety Issue)

Other findings:
• The forecast weather at Lockhart River for the time of the aircraft’s arrival required the pilot to plan for 60 minutes holding or diversion to an alternate aerodrome. The aircraft had sufficient fuel for that purpose; and the aircraft had sufficient fuel to conduct the flight from Cairns to Lockhart River and return, with additional fuel for holding on both sectors if required.
• There was no evidence of any organizational or commercial pressure to conduct the flight to Lockhart River or to complete the flight once to commenced.
• Based on the available evidence, it is very unlikely that the pilot was incapacitated or impaired during the flight.
• There was no evidence of any aircraft system or mechanical anomalies that would have directly influenced the accident. However, as a consequence of extensive aircraft damage, it was not possible to be conclusive about the aircraft’s serviceability.
• The aircraft was fitted with Garmin GNS 430W GPS/navigational units that could be configured to provide visual (but not aural) terrain alerts. However, it could not be determined whether the
terrain awareness function was selected on during the accident flight.

The following contributing factors were identified:
- Hazardous weather conditions were forecast and present at the drop site near Peak View, which included strong gusting winds and mountain wave activity, producing turbulence. These
conditions were likely exacerbated by the fire and local terrain.
- The Rural Fire Service continued the B134 tasking to Adaminaby when they learned that no other aircraft would continue to operate due to the environmental conditions. In addition, they relied on the pilot in command to assess the appropriateness of the tasking to Adaminaby without providing them all the available information to make an informed decision on flight safety.
- The pilot in command of B134 accepted the Adaminaby fire-ground tasking, which was in an area of forecast mountain wave activity and severe turbulence. After assessing the conditions as unsuitable, the crew accepted an alternate tasking to continue to the Good Good (Peak View) fire-ground, which was subject to the same weather conditions. The acceptance of these taskings were consistent with company practices.
- Following the partial retardant drop and left turn, the aircraft was very likely subjected to hazardous environmental conditions including low-level windshear and an increased tailwind component, which degraded the aircraft’s climb performance.
- While at a low height and airspeed, it was likely the aircraft aerodynamically stalled, leading to a collision with terrain.
- Coulson Aviation's safety risk management processes did not adequately manage the risks associated with large air tanker operations. There were no operational risk assessments conducted or a risk register maintained. Further, as safety incident reports submitted were mainly related to maintenance issues, operational risks were less likely to be considered or monitored. Overall, this limited their ability to identify and implement mitigations to manage the risks associated with their aerial firefighting operations. (Safety issue)
- Coulson Aviation did not provide a pre-flight risk assessment for their firefighting large air tanker crews. This would provide predefined criteria to ensure consistent and objective decision-making with accepting or rejecting tasks, including factors relating to crew, environment, aircraft and external pressures. (Safety issue)
- The New South Wales Rural Fire Service had limited large air tanker policies and procedures for aerial supervision requirements and no procedures for deployment without aerial supervision.(Safety issue)
- The New South Wales Rural Fire Service did not have a policy or procedures in place to manage task rejections, nor to communicate this information internally or to other pilots working in the same area of operation. (Safety issue)

Other factors that increased risk:
- The B134 crew were very likely not aware that the 'birddog' pilot had declined the tasking to Adaminaby fire-ground, and the smaller fire-control aircraft had ceased operations in the area, due to the hazardous environmental conditions
- In the limited time available, the remainder of the fire-retardant load was not jettisoned prior to the aircraft stalling.
- Coulson Aviation did not include a windshear recovery procedure or scenario in their C-130 Airplane Flight Manual and annual simulator training respectively, to ensure that crews consistently and correctly responded to a windshear encounter with minimal delay. (Safety issue)
- Coulson Aviation fleet of C-130 aircraft were not fitted with a windshear detection system, which increased the risk of a windshear encounter and/or delayed response to a windshear encounter during low level operations. (Safety issue)
- The New South Wales Rural Fire Service procedures allowed operators to determine when pilots were initial attack capable. However, they intended for the pilot in command to be certified by the United States Department of Agriculture Forest Service certification process. (Safety issue)

Other findings:
- The aircraft's cockpit voice recorder did not record the accident flight, which resulted in a valuable source of safety information not being available. This limited the extent to which potential factors contributing to the accident could be identified.

Contributing factors:
• The flight instructor very likely conducted a simulated engine failure after take-off in environmental conditions and a configuration in which the aircraft was unable to maintain altitude with one engine inoperative.
• Having not acted quickly to restore power to the simulated inoperative engine, the pilots did not reduce power and land ahead (in accordance with the Airplane Flight Manual procedure) before the combination of low airspeed and bank angle resulted in a loss of directional control at a height too low to recover.
• The instructor had very limited experience with the aircraft type, and with limited preparation for the flight, was likely unaware of the landing gear and flap retraction time and the extent of their influence on performance with one engine inoperative.

Other factors that increased risk:
• The pilot had not flown for 3 years prior to the accident flight, which likely resulted in a decay in skills at managing tasks such as an engine failure after take-off and in decision-making ability. The absence of flying practice before the flight review probably affected the pilot’s ability to manage the asymmetric low-level flight.
• The aircraft had not been flown for more than 2 years and had not been stored in accordance with the airframe and engine manufacturers’ recommendations. This very likely resulted in some of the right engine cylinders running with excessive fuel to air ratio for complete combustion and may also have reduced the expected service life of both engines’ components.
• The right-side altimeter was probably set to an incorrect barometric pressure, resulting in it over-reading the aircraft’s altitude by about 90 ft.