Although airtankers and helicopters are a highly visible part of wildfire response, they do not put out wildfires on their own. 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 fire containment and suppression. The Province’s contracted aircraft fleet is repositioned as needed during the fire season to be ready for anticipated fire starts in high-risk areas.
This assistance may be in the form of:
- initial attack on wildfires that are predicted to (or threatening to) exceed the capabilities of firefighting resources on the ground
- support crew activities on wildfires where specific, attainable objectives have been identified
- holding action on wildfires where a delay in the arrival of ground resources is anticipated
This assistance can include:
- supporting and reinforcing existing control lines
- limiting the spread of a wildfire by performing controlled drops on or in front of a small fire (or a portion of a larger fire)
- cooling down hot spots
- protecting specific values, such as structures that are imminently threatened by a wildfire
Airtankers usually fly in groups of up to four aircraft with a combined capacity of up to 16,000 litres of fire retardant, or over 11,000 litres for a single, heavier aircraft. Each group is led by a “bird dog” plane that directs the airtankers to the most effective and safe drop locations.
There are two types of firefighting airtankers: land-based airtankers and water-skimmer airtankers. B.C. uses both types. Over the course of an average wildfire season, the B.C. government’s contracted airtankers conduct about 560 missions throughout the province. At full operational readiness, the BC Wildfire Service operates a fleet of 20 airtankers and eight bird dog aircraft (in addition to its contracted helicopter fleet).
Amphibious airtankers are able to “skim” water from lakes and rivers. The BC Wildfire Service’s fleet includes 10 Air Tractor AT-802F Fire Boss amphibious airtankers. They can drop either water, foam or fire retardant, 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.
The BC Wildfire Service uses helicopters primarily to transport firefighting 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 deploying crews who can rappel down to the site of a wildfire when there is no alternative means of access (or limited access).
Helicopters can also be used to drop fire retardant, foam or water on a fire. Water is either scooped up in a large ”bucket” that hangs beneath the helicopter or drawn up into a “belly tank” integrated into the body of the helicopter. Foam can then be added to the belly tank if required.
During the wildfire season, the BC Wildfire Service has exclusive access to five medium-lift helicopters, three medium-lift helicopters equipped with rappel and hoist equipment, and one light-lift helicopter. Many more helicopters are available to assist with wildfire response on short-term contracts, as needed. Helicopters can lift between 360 litres and 9,000 litres of liquid, depending on the type of helicopter and the weather conditions.
Fire retardant, foam and water can all be used to slow a fire’s growth. They are not used to put out fires, but to cool them down and slow their progress. This supports the efforts of ground crews who are working to contain a fire.
Retardants are commonly used in fire suppression because of their long-lasting effect on fire behaviour. They are usually dropped ahead of an advancing fire by airtankers and helicopters to help contain the wildfire.
Retardants contain ammonium salts and are essentially water-soluble, industrial-strength fertilizer (with colouring added) that affect the burning process of forest fuels. The colouring, which gives fire retardant its characteristic red colour, allows crews to easily see where the retardant has landed. When flames come into contact with retardant, the resulting reaction releases a combination of water and carbon dioxide that helps cool and suffocate the fire.
Foam can also be used to help suppress a wildfire. It absorbs the heat from combustion while its bubble structure slowly releases water, which is absorbed by wood fuels.
Depending on the ratio of water to foam concentrate, the resulting mixture is either a “dry” or “wet” foam. Dry foams have smaller, high-insulation bubbles that offer greater heat absorption, while wet foams have larger bubbles that allow water to penetrate forest fuels more easily. Wet foams are generally considered to be more effective fire suppressants because dry foams are difficult to apply effectively (often getting caught in wind currents or tree canopies).
Water is used to both suppress and extinguish wildfires. It 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 used for water drops, where appropriate.