On 6 April 2020, the Royal Commission into National Natural Disaster Arrangements (RCNDA) issued a notice to give information to the ATSB. Within this notice was the requirement to ‘describe any key operational and safety challenges encountered in co-ordinating and responding to fires associated with the use of aircraft and aerial firefighting techniques’. Below is part of the ATSB’s response to the Royal Commission’s notice to give information.

Since 2018, the ATSB has commenced six investigations involving aerial firefighting aircraft, including the investigation (AO-2020-007) into the collision with terrain involving a Lockheed C‑130 near Cooma, New South Wales, on 23 January 2020.

What the ATSB found

Aerial firefighting activity has increased over recent bushfire seasons. However, official exposure data (hours flown and flights for Australian-registered aircraft) before 2014 and beyond 2018 were not available to the ATSB for this report. Estimates of aerial firefighting activity for the most recent bushfire season (2019-20) have been around four-times higher than other recent bushfire seasons.

There were more reported occurrences* involving aerial firefighting aircraft in Australia in the financial year covering the last bushfire season (between July 2019 and March 2020) than any financial year since July 2000 (Figure 1). In addition, there have been two fatal accidents since August 2018, whereas the previous 17 years only counted three fatal accidents. Further, the number of occurrences per financial year increased steadily since 2016-17. Given the increased activity, these results could be expected and probably do not indicate a significant increase in the risk per flight (a more extensive analysis would incorporate exposure data for the full 20-year study period if the data were available). Over the full 20-year study period, all fatal accidents, and around 40 per cent of other occurrences, happened in New South Wales.

Around three quarters of aerial firefighting occurrences involved Australian VH‑registered aircraft. Foreign‑registered aircraft accounted for the bulk of the remaining occurrences. Probably reflective of increased activity, the proportion of occurrences involving foreign‑registered aircraft increased significantly over the study period. Between July 2019 and March 2020, foreign‑registered aircraft were involved in two thirds of more severe occurrences (serious incidents, accidents and fatal accidents).

The average maximum take‑off weight (MTOW) of aerial firefighting aircraft involved in a reported occurrence increased significantly over the study period. Foreign‑registered aircraft, which had an average MTOW around 10 times that of VH‑registered aircraft, contributed most to this increase.

Between 2014 and 2018 (the period with available exposure data – departures and hours flown), the rate of reported occurrences involving VH‑registered aircraft was consistent between aeroplanes and helicopters. VH‑registered piston‑powered helicopters had around double the rate of more severe occurrences than turboshaft helicopters.

Half of all reported aerial firefighting occurrences and four fifths of more severe aerial firefighting occurrences were operational in nature, typically terrain collisions, with around one quarter of the more severe occurrences associated with aircraft control. Furthermore, around one quarter of more severe occurrences involved a technical issue, most commonly engine failure or malfunction.

Additional risks to those inherent to low‑level flying can be seen in higher occurrence rates compared to other low‑level flying activities. Between 2014 and 2018, VH‑registered aerial firefighting aircraft had higher rates of communication‑related occurrences, flight preparation/navigation operational occurrences, aircraft separation occurrences, operational non‑compliance occurrences, airframe‑related technical issues, and encounters with remotely piloted aircraft. Aerial firefighting had lower rates for terrain collision and aircraft control related occurrences.