Applying the aerospace industry to Australian bush fire control

The beginning of April marked the end of Australia’s fire season, the latest in the series that could rightfully be characterized as one of the worst ever. Informally known as the Black Summer, the 2019/2020 fire season saw months of drought and extremely high temperatures result in:

- at least 33 people dead with more missing;
- close to 6,000 buildings destroyed, out of which are roughly 3,000 homes;
- more than 11 million hectares (110,000 sq km or 27.2 million acres) of bush, forest, and parks across the country burned;
- more than one billion animals killed, putting some species to the brink of extinction.

As the effects of the devastation are slowly summarized, there are already plans in motion to prepare for the upcoming season, which may start as early as June if Black Summer is any indication. With those preparations comes a proposal from the International Space Association (ISA) to fight fires with a new approach: using the Royal Australian Air Force (RAAF) to help fight and control bushfires.

A new way to fight fires

Linking an organization dedicated to exploring, visiting, and working in space with bushfires may not come as natural at first but there is a sound basis behind the proposal.

The traditional/current way of fighting wildfires leaves a lot to be desired as large fires generate tremendous amounts of heat, forcing firefighters on the ground to distance themselves and making their equipment ineffective in the process. Instead, they have to rely on helicopters and air tankers (fire-bombing planes) that drop water, foam, gel, and/or fire-retardant solutions.

At best, a combination of land-based equipment (including bulldozers and excavators that clear areas to stop the fire’s advance) and aircraft is barely making the fires controllable, provided strong winds and rising temperatures don’t aggravate the situation further.

A new approach to disaster management aims to innovatively disrupt the holy bond of oxygen, fuel, and heat via acoustic waves, first suggested by Mike Benitez, an F-15E Strike Eagle Weapons Systems Officer in the U.S. Air Force.

Namely, any aircraft capable of traveling at a speed greater than the speed of sound would be used to create a sonic boom, resulting in a shock wave. The shock wave forms pressurized air molecules gathered in the shape of a cone, which moves outward and rearward in all directions and extends to the ground. The continuous effect that occurs along the flight path fills out a narrow path on the ground, also known as the boom carpet, where a sudden change in pressure across the shock wave, combined with the impulse of the airflow behind it, “push” the flame straight off the fuel source, thus suppressing and extinguishing the fire.

An important factor is the altitude of the aircraft as both the width and intensity of the boom carpet depend on it. According to NASA, the width is approximately one mile for every 1000 feet of altitude. Generally speaking, the higher the aircraft is, the greater the distance the shock wave must travel to the ground, lessening the sonic boom’s intensity.

There are plenty of combinations to work out and ultimately, leverage, as several other factors such as the weight, size, and shape of the aircraft, its attitude, flight path, as well as atmospheric conditions can influence sonic booms. With that in mind, the role of the air force is to utilize its personnel and equipment and adjust it for firefighting conditions. For instance, a variety of its aircraft fleet can provide the necessary combination of shapes, sizes, and altitudes that could be precisely tailored to specific terrain engulfed in flames.

Fighting on scale

ISA first made a proposal to the Minister of Defence, Senator the Hon Linda Reynolds CSC regarding the use of RAAF jets in aerial firefighting. Our proposal was quickly forwarded to the Royal Australian Air Force headquarters, eliciting a comment from Air Vice-Marshal and Deputy Chief of Air Force Stephen Meredith AM, DSM that there is evidence to suggest that the use of acoustic waves could be optimized for fire suppression at a small scale.

Further analysis of the potential effectiveness is required in regards to the current Australian conditions, along with the need for a collective output supplemented with the fire and emergency agencies. Here at ISA, we have proposed an experiment to test the potency of using air force jets in helping control a bush fire, specifically the assistance of F35 jets focusing on creating a sonic boom and examining the following effects. The results would be used to examine the justification of using acoustic waves in containing and quelling a controlled bush fire, as well as reintroducing the predictability factor to the firefighting effort on the ground.

As per the comment of the Deputy Chief of Air Force, Prime Minister Scott Morrison released the Terms of Reference for the Royal Commission into National Natural Disaster Arrangements (established in February 2020 in response to the extreme bushfire season of 2019-20), following an agreement from the Governor-General of the Commonwealth of Australia, His Excellency General the Honourable David Hurley AC DSC (Retd). The Royal Commission will look at several areas regarding improving natural disaster management, Australia’s level of preparedness, resilience, and response to natural disasters. As of yet, RAAF keenly awaits the Royal Commission’s recommendations before it investigates the merits of ISA’s proposal.

Final thoughts

In an area where extremely high temperatures and months of drought are fairly common, we fear that the scale and intensity of this year's fires might turn into a more frequent occurrence. Even if that turns out to be false, the fact remains that the Australian government needs to take further steps to prepare for future scenarios, especially those with more extreme outcomes.

So far, the idea of adding the sonic boom into the airborne firefighting fold shows a lot of promise. If properly combined and implemented, it could have an immediate effect on small-scale fires, allowing the ground efforts to engage fires on a more manageable level, possibly even reducing the volume of fires that are ‘too big to put out’ over time. It might be the key to minimizing the total fire damage and avoiding finding ourselves in yet another unprecedented scenario. After all, we can’t depend on rainfall or fires burning themselves out.


Dr Jeremy Nunn

Mr Christopher Beach

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