While airtankers and helicopters are a highly visible part of wildfire response, they do not put out wildfires. Rather, they provide critical support to our crews on the ground.
Depending on fire behaviour, location and weather conditions the BC Wildfire Service may deploy fixed wing and/or rotary wing aircraft (i.e. helicopters) to assist with containment and fire suppression.
This assistance may be in the form of:
- Initial attack on wildfires predicted, or threatening, to exceed the capabilities of ground resources
- Support action on wildfires where specific, attainable objectives have been identified for example by
- Holding action on wildfires where a delay in the arrival of ground resources is anticipated
And can include:
- Supporting and reinforcing existing control lines
- Limiting the spread of a wildfire (by performing controlled drops on, or in front of, small fires or a portion of larger fires)
- Cooling hot spots (by drops on these areas to bring the temperature down)
- Protecting specific values, such as structures imminently threatened by wildfire
Fixed Wing Aircraft
Airtankers usually fly in groups of up to four aircraft with a combined capacity of up to 16,000 litres of retardant, or over 11,000 litres for single, heavy aircraft. Each group is led by a “bird-dog” plane which directs the group to the most effective and safe drop locations.
At full operational readiness the BC Wildfire Service operates a fleet of 16 airtankers and 8 bird-dog aircraft.
Amphibious airtankers (also known as ‘water bombers’) are able to “skim” water from lakes and rivers. The BC Wildfire Service’s aerial fleet includes four Air Tractor AT-802F “Fire Boss” amphibious airtankers. These can drop water, foam or retardant on a fire and each is capable of skimming up to 3,025 litres of water in 15 seconds from over 1,700 bodies of water in B.C.
Rotary Wing Aircraft
The BC Wildfire Service uses helicopters primarily to transport fire crews, fire line personnel and equipment during the initial attack and sustained action phases of wildfire response. Helicopters are also used for infrared scanning, mapping and/or observation of fires; and, for the deployment of rappel crews on wildfires that have little or no alternative means of access.
Helicopters can also be used to drop retardant, foam and/or water on to a fire. Water is either scooped up in a large ‘bucket’ which hangs beneath the helicopter or drawn up into a ‘belly tank’ integrated into the body of the helicopter where it may then be injected with foam.
The BC Wildfire Service has exclusive access to five medium lift and one light lift helicopter during fire season with many more available on short-term contracts as needed. Helicopters have the capacity to lift between 360 litres to 9,000 litres depending on helicopter type and weather conditions.
Fire retardants, foams and water can be used to slow a fire. They are not used to put out fires, but rather to cool them and slow their progress. This supports the efforts of ground crews in containing a fire.
Retardants are used most commonly in fire suppression because of their long-lasting effect on fires and are usually dropped ahead of an advancing fire by airtankers and helicopters to help contain the wildfire.
Containing ammonium salts, retardants are essentially water soluble, industrial strength fertiliser with colouring, which affect the burning process of forest fuels. The colouring, which gives retardant its characteristic red colour, enables crews to see where the retardant has landed. When the flames come into contact with retardant, the resulting reaction releases a combination of water and carbon dioxide that cools and suffocates the fire.
Foam is used to suppress fire; when dispersed on a wildfire, foam absorbs the heat from combustion while the bubble structure slowly releases water, which is absorbed by wood fuels. Depending on the ratio of water and concentrate a foam mixture can produce either a dry or wet foam. Dry foams produce smaller high insulation bubbles which offer greater heat absorption, while wet foams develop larger bubbles that provide better water penetration. Wet foams are generally considered more effective fire suppressants because dry foams are difficult to apply effectively, often becoming caught in wind currents or tree canopies.
Water is used to both suppress and extinguish wildfires and is typically applied by ground crews using water bags, tanks, pumps and hoses, or by helicopters equipped with buckets or belly tanks. Amphibious airtankers that can ‘scoop’ water from lakes and rivers may also be utilized for water drops if deemed appropriate.