The Australian Transport Safety Bureau (ATSB) has released their final report on the January 23, 2020 crash of a C-130, Air Tanker 134, Bomber 134 (B134) as it was known in Australia. All three crewmembers were killed just after dropping retardant on a fire for the Rural Fire Service (RFS) in New South Wales, Australia.
It was very windy on January 23, with a forecast for the possibility of mountain waves. Before the incident a bird dog, similar to a lead plane, and Bomber 137 (B137), a Boeing 737, was tasked to drop on a fire in the Adaminaby area. Based on the weather the bird dog pilot declined the assignment. After B137 made a drop on the fire, the crew reported having experienced uncommanded aircraft rolls up to 45° angle of bank (due to wind) and a windshear warning from the aircraft on-board systems.
After completing the drop, the B137 crew sent a text message to the bird dog pilot indicating that the conditions were “horrible down there. Don’t send anybody and we’re not going back.” They also reported to the Cooma FCC that the conditions were unsuitable for firebombing operations. During B137’s return flight to Richmond, the Richmond air base manager requested that they reload the aircraft in Canberra and return to Adaminaby. The Pilot in Command (PIC) replied that they would not be returning to Adaminaby due to the weather conditions.
B134 was also dispatched to the fire at Adaminaby. While they were in route, the PIC of B137 called to inform them of the actual conditions, and that B137 would not be returning to Adaminaby.
After arriving at Adaminaby, the PIC of B134 contacted the air operations officer at the Cooma FCC by radio and advised them that it was too smoky and windy to complete a retardant drop at that location.
The Cooma air operations officer then provided the crew with the location of the Good Good Fire, about 58 km to the east of Adaminaby, with the objective of conducting structure and property protection near Peak View. Again, there was no birddog operating with the air tanker.
The C-130 went to Peak View as the only aircraft on scene. After dropping a partial load of retardant out of the 4,000-gallon tank the aircraft then made a left turn which resulted in a tail wind and it climbed for approximately 10 seconds to about 170 feet above the drop height. Following this, the aircraft was observed descending. It was seen at a very low height above the ground, in a slight left bank, immediately followed by a significant left roll as the left wing struck a tree just before ground impact. The three crewpersons were fatally injured and the aircraft destroyed.
The report’s findings
The ATSB determined from a combination of witness video and real-time position and flight path data, that the aircraft’s climb performance degraded. Subsequently, while at a low height and airspeed, it was likely the aircraft aerodynamically stalled, resulting in a collision with terrain. In the limited time available, the remainder of the fire-retardant load was not jettisoned prior to the aircraft stalling.
As there were only about 10 seconds between the climb performance degrading and the likely stall, there was limited time available for the crew to identify and respond to the situation. Past research shows pilot recognition time of windshear can be expected to be about 5 seconds, and the emergency dump function would take a further 2 seconds. However, in the absence of the cockpit audio recording, it could not be determined if the crew had considered or called for an emergency dump of the remaining load. Therefore, for reasons undetermined, the remaining 25,000 pounds of retardant was not jettisoned during the accident sequence.
The ATSB established that jettisoning the remaining load would have lowered the stall speed and optimised the aircraft’s climb performance. This was also confirmed from the simulator testing. Nonetheless, it was not possible to determine if jettisoning the remaining load, taking into account the time available, and typical recognition and response times, would have prevented the collision with terrain. The outcome of the July 1, 2012 crash in South Dakota of MAFFS 7, a US Air Force C-130 where the crew did jettison the load, is an example of when this action may not be sufficient to avoid a collision with terrain.
While the New South Wales RFS was not an aviation organization or directly responsible for flight safety, they were closely involved in the aerial operation, being responsible for determining the task objectives and selecting aircraft for the task. The ATSB found that the RFS had limited large air tanker policies and procedures for aerial supervision requirements and no procedures for deployment without aerial supervision. In addition, they 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. Such policies and associated procedures would provide frontline personnel with the required steps to effectively and safely manage taskings, and provide guidance for decision-making.
It was also identified that while not applicable to the accident crew, the RFS procedures allowed aircraft operators to determine when pilots were initial attack capable. This was inconsistent with their intention for pilots to be certified by the United States Forest Service certification process.
The ATSB also determined that 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. The RFS 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.
While not contributing to the accident, the aircraft’s cockpit voice recorder did not record the accident flight and had not worked for weeks or more after having being automatically triggered off by some event during training flights. This resulted in a valuable source of safety information not being available to the investigation, which not only increased the time taken to determine contributing factors to the accident but also limited the extent to which important safety issues could be identified and analysed.
What has been done as a result
As a result of this investigation, Coulson Aviation has incorporated a windshear recovery procedure into their C-130 Airplane Flight Manuals and plan to introduce simulator-based recurrent windshear training. Related to the consideration of risk in aerial firefighting operations, they have also implemented a pre-flight risk assessment to be completed by the pilot in command prior to the first tasking of the day. They will also be introducing a three-tiered risk management approach of organizational risk, operational risk, and tactical/mission risk, to be utilized during the upcoming fire season in Australia. Further, Coulson Aviation has updated their pre-flight procedures to incorporate a cockpit voice recorder system check before each flight. Lastly, the Retardant Aerial Delivery System software was reprogrammed so that the system will not require re-arming between partial load drops where less than 100% was selected.
The ATSB has issued two safety recommendations to Coulson Aviation. These are to further consider:
- Fitment of a windshear detection system to their C-130 aircraft to minimise the time taken for crews to recognise and respond to an encounter particularly when operating at low-level and low speed;
- Incorporating foreseeable external factors into their pre-flight assessment tool to ensure the overall risk profile of a tasking can be consistently assessed by crews.
The New South Wales Rural Fire Service advised the ATSB that they intend to take the following actions in response to this accident:
- Commissioned an independent report into the management of airspace in which aircraft are operating in support of fire-fighting activities;
- Formalize and establish a “Large Air Tanker Co-ordinator” role description, to be positioned on the State Air Desk during heightened fire activity;
- Undertake an immediate audit, in conjunction with operators, of pilots qualified as initial attack capable and ensure appropriate records are accessible by RFS personnel;
- Undertake detailed research to identify best practice (nationally and internationally) relating to task rejection and aerial supervision policies and procedures as well as initial attack training and certification.
- Undertake a comprehensive review of RFS aviation doctrine to incorporate outcomes of the above-mentioned research into existing policies and procedures;
- Promulgate the revised doctrine detailing the task rejection policies and procedures and aerial supervision requirements to all operational personnel, pilots/aircrew and other key stakeholders. This is to be reinforced at the aviation operators briefing held annually prior to the bushfire season;
- Provide the National Aerial Firefighting Centre and national fire-fighting agencies with copies of the updated doctrine relating to these issues.
While the ATSB acknowledges the commitment to undertake reviews and research, at the time of publication the New South Wales Rural Fire Service had not yet committed to adopting any safety action that would reduce the risk associated with the three identified safety issues to an acceptable level. As such, the ATSB has issued three safety recommendations to the RFS to take further action:
- To address the absence of policies and procedures for personnel to effectively manage and communicate task rejections on the basis of operational safety concerns;
- To address the absence of policies and procedures regarding minimum aerial supervision requirements and the use of initial attack to assist frontline staff with making acceptable risk-based tasking decisions;
- To address the ambiguity with the interpretation of “initial attack” in NSW and the Australian Capital Territory Aviation Standard Operating Procedures.
Britton Coulson, Co-President of Coulson Aviation, told Wildfire Today, “We worked very closely with the ATSB to provide them with all the information that they requested. We are pleased that they acknowledged the progress we made with their recommendations.”
The final 4 mb report can be downloaded.