page_title: Aerial firefighting and forestry in southern Australia
section_title: Aerial ignition
hierarchical_section_title: Aerial firefighting and forestry in southern Australia / Aerial ignition
caption_attribution_description: English: Aerial Incendiary Machine - Victoria Valley, Grampians - Autumn 1980
context_page_description: The development of aerial firefighting and forestry in southern Australia ran in parallel with the rapid improvements in aircraft technology over the last century. As more advanced and capable aircraft became available firefighters and foresters quickly sought opportunities to utilise and adapt them.
  Aircraft have three main advantages over ground resources: speed, access, and observation.
  Aircraft have been used for a wide range of tasks including reconnaissance, firebombing, crew transport, aerial ignition, back burning, gathering infrared imagery as well as operational forestry tasks like aerial photography, surveys, spraying, fertilising and seeding.
  Much of the early pioneering work in Australia was led by the Forests Commission Victoria in collaboration with other State forestry and fire authorities including the Western Australia Forests Department, Forestry Commission of NSW, Woods and Forest Department of South Australia and Forestry Tasmania. Federal agencies including the CSIRO also contributed significantly.
context_section_description: Experience and research have shown that reducing available fuel influences the rate of spread and intensity of bushfires. Other factors such as the weather, wind speed, relative humidity and temperature cannot be controlled.
  From the early 1960s pioneering work by foresters in Western Australia in conjunction with Bob Vines and David Packham from the CSIRO Division of Physical Chemistry developed aerial ignition techniques to reduce fuels under mild conditions over vast areas of the relatively flat terrain of Western Australia's state forest.
  A machine was designed to drop small plastic capsules of potassium permanganate crystals which were injected with ethylene glycol just before being ejected from the aircraft. A delayed chemical reaction resulting in a small fire on the ground lasted for some 30 seconds. The first trial was at Manjimup in December 1965 and later improvements followed. The spacing of the ignitions was about 200 m and could be controlled by the adjusting the speed of the aircraft to about 100 knots and adjusting the dwell between drops to one every four seconds. Great emphasis was placed on maintaining an even grid pattern but this proved a demanding task flying 400 feet above the ground and various techniques were tried.
  While the development of an aerial incendiary machine by the CSIRO was progressing the Forests Commission Victoria was developing a system for use with helicopters.  The DIAD (Delayed Action Incendiary Devices) was a large double-ended match with a length of safety fuse between. Forestry Tasmania started using DIADs around the same time. They were stored in a metal box outside the helicopter along with a disposable striker patch attached to a special half-door. A navigator sat in the middle beside the pilot and the bombardier's role was to strike and then drop the lighted DIADs. After about 17 seconds the large section of the DIAD would ignite and burn for a further 40 seconds, enough to start a small spot fire on the ground. The first test was with a Bell 47G on 4 October 1967. Helicopters gave several advantages over fixed wing aircraft including flexibility and greater accuracy of placing incendiaries from a slow-moving aircraft.
  For larger operations in the remote mountains or desert, a helicopter would fly along ridgetops and ignite hundreds of hectares by dropping DAIDs. The fire would be allowed to trickle slowly down the north facing slopes in the evening until it went out overnight with the dew the following morning or ran into a wet gully. But the 1970s were a relatively wet decade so the gullies were damp and full of soggy tree ferns which would stop most burns. Also, there weren't many people in the bush other than loggers and cattlemen, so it was possible to do this with minimal risk. The first use, anywhere in the world, of DAIDs to backburn a large 49 800 acre fire in north eastern Victoria was undertaken by the Commission in February 1968. 
  In April 1969 the Forests Commission used a CSIRO incendiary machine in a Cessna 337 to carry out fuel reduction burning at Orbost which prompted the purchase their own machine. Later in 1977, the Commission purchased a Canadian designed Premo aerial incendiary machine which dropped incendiaries in small polystyrene “ping pong” balls. The machine was certified for use by the Civil Aviation Safety Authority (CASA) in April 1978.
  However, the crash of a helicopter conducting aerial ignition on 19 April 1978 with the death of two forest officers and the pilot  profoundly shook the small "Fraternity of Foresters".  But it led to better accident insurance for staff involved in air operations, the end of DAIDs and the wider adoption of the safer ping-pong ball aerial incendiary machine.
  High intensity slash burning is usually needed to achieve satisfactory regeneration after logging and the ping-pong ball machine was not suitable for aerial ignition because a large amount of fire needs to be introduced onto the logging coupe quickly. These areas are also often in steep terrain making ground ignition by crews difficult and dangerous. An id
caption: Premo "ping pong" ball aerial incendiary machine fitted into a Bell 206 Jet Ranger at the Victoria Valley, Grampians, Autumn 1980. Photo: Peter McHugh. FCRPA* collection.
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