Investigating the suitability of aviation tracking data for use in bushfire suppression effectiveness research

Aircraft are an important part of bushfire suppression and their use is increasing. They were used heavily during the 2019/20 “Black Summer” bushfire season in NSW and several inquiries have highlighted the need for research into their effectiveness.

Tracking equipment is becoming routinely deployed on aircraft and there is increasing availability of high-quality ancillary data such as aerial imagery and fire severity mapping. These allow detailed analyses of aircraft activities. However, the usefulness of the data needs to be evaluated, and the analysis needs to be informed by information about the tasking objectives of the aircraft and whether those objectives were met.

This project provides an initial investigation into the process of evaluating aerial suppression using these new data sources and interviews with personnel involved in the suppression activities.

Firebombing event data (drops/fills) from the 2019/2020 bushfire season in NSW from the National Aerial Firefighting Centre (NAFC)’s Arena database was provided by the NSW Rural Fire Service. This data included ~70000 aircraft suppression drop locations and times from aircraft that included helicopters (mainly large and medium helitaks), Single-Engine Air Tankers and Large Air Tankers. As an initial step, we examined the data for completeness, accuracy and errors, and described the data contents. This data was missing for most of the aircraft known to be dropping on the fires, especially the smaller ones. The type of drop (gel, water, retardant) was unknown in most cases, the quantity dropped was unknown in 45% of cases, and the location for the end of drops was often unreliable.

We then tested methods to identify drop objectives based on relationships between drops data and other spatial data including building locations and weather. Using a combination of automated pattern matching and manual checking, the data can be used to identify cases where the objective was initial attack, extinguishing spot fires, asset protection, pre-emptive laying of retardant lines and direct attack. There were a few cases where the success or failure of the objective could be assessed purely with the spatial data. We also explored two particular analytical methods for determining objectives. First, we compared the distribution of Forest Fire Danger Index (FFDI, fire weather) during a fire and for the drops within that fire. This identified several fires for which a large proportion of the drops were more likely to be during extreme fire weather even though extreme weather was rare in that fire. Second, we compared the distribution of distance to houses between all parts of the fire and the drops at that fire. Here we found many fires where the drops were clustered closer to houses than if the drops were (hypothetically) spread evenly across the fire ground. These analyses are preliminary but show great potential.

We conducted 10 interviews with personnel who worked as Air Attack Supervisors during the 2019/20 season. Interviewees were knowledgeable and experienced, and expressed the view that the aerial program could be improved with further knowledge sharing and training. They provided a lot of general information about objectives, how they learned during the season, their views on limitations in aerial suppression, and their own capacity to document the process.

The interviews also highlighted several operational issues that warrant more investigation using a large number of aviation specialists and more specific questions. Chief among these are:

• To what extent does smoke and bad weather limit the capacity to deliver aerial suppression?
• The development of guidelines of the most appropriate tasks for each aircraft type (e.g., the LATs being used for strategic drops in locations away from smoke plumes). Can these be clarified to maximize the effectiveness of the aerial resources and if so, how could this be addressed?
• Do IMTs sometimes overestimate the capabilities of aerial suppression, especially during bad weather, and if so, how can this be addressed?

We conducted eight detailed case studies where there were interesting features in the drop data and insightful comments from the interviewees. These were particular days at a particular part of a fire. They included one example with multiple objectives playing out as one failed and the fire spread changed, several where property protection was the dominant objective (largely successful), one on spot fires, and two initial attacks, of which one succeeded and the other failed.  The case studies demonstrate the power of the approach where spatial data and interview interpretation are combined.

The air drop data has the potential to enable deep analyses of aircraft use and effectiveness during real bushfire responses, especially when combined with other contextual information, such as objectives and environmental conditions. This will require more matching of the data to interviews to determine whether the drop data can be used in this way. We have started this process in this report, identifying clear clusters of activity related to weather and distance to houses, and cross-checking with interviews in the case study, and in some of these cases, the success could be judged. In order to realise the full potential of this approach, the completeness and accuracy of the drop data should be improved and interviews should become a routine part of the seasonal review process.