Air attack is an industry term used for the actual application of aerial resources, both airtanker and helitack, on a fire, although colloquially, "air attack" is also a term used for the airborne manager in a spotter plane who is charged with directing the use of the aerial resources. Initial attack refers to the first-response of aerial assets to suppress a fire before it grows out of control; aviation assets can usually respond to a reported blaze much quicker than ground elements, especially for wilderness fires. Extended attack refers to the continued use of aerial assets on an out-of-control fire, primarily to assist ground units in the establishment of firelines in advance of the fire.
Airtankers or water bombers are fixed-wing aircraft fitted with tanks that can be filled on the ground at an air tanker base or, in the case of flying boats and amphibious aircraft, by skimming water from lakes, reservoirs, or large rivers.
Various aircraft have been used over the years for firefighting. Though World War II era bombers were for a long time the mainstay of the aerial firefighting fleet, newer purpose-built tankers are coming online. The smallest are the Single Engine Air Tankers (SEATs). These are agricultural sprayers that generally drop about 800 gallons of water or retardant. Medium aircraft include the S-2 Tracker (retrofitted with turboprop engines as the S-2T) as used by the California Department of Forestry & Fire Protection (CDF), as well as Conair Group Inc. of Abbotsford, British Columbia, while the Douglas DC-4, the DC-7, the Lockheed C-130 Hercules, P-2V Neptune, P-3 Orion and others have been used as heavy tankers. The largest aerial firefighters currently in use include two converted Martin Mars flying boats in British Columbia (one of which was brought to southern California in September 2007 to help battle the wildfires there), carrying 7,200 U.S. gallons of water or fire retardant each, and Tanker 910, a converted McDonnell Douglas DC-10 that can carry 12,000 gallons of water or retardant. The Russian Ministry of Emergency Situations operates convertible-to-cargo IL-76 airtankers that can carry up to 15,000 gallons but have been operating with 11,000 gallon tanking systems, and Evergreen International Aviation is developing a Boeing 747 aerial firefighter, known as the Evergreen Supertanker that can carry 24,000 gallons fed by a pressurized drop system.
Bombardier's Dash 8 Q Series aircraft are the basis for two new ventures. Cascade Aerospace has converted two pre-owned Q400s to act as part-time water bomber and part-time transport for France's Sécurité Civile, one of which is registered F-ZBMC, while Neptune Aviation is converting a pre-owned Q300 as a prototype to augment their P2V aircraft.
Similar in configuration to the World War II-era PBY Catalina, the Canadair CL-215 Scooper, and Bombardier CL-415 SuperScooper are designed and built specifically for firefighting. The "Super Scoopers" are not common in the United States where only 2 operate seasonally in southern California. Los Angeles County leases two CL-415s from the Province of Québec during the fall when the Santa Ana winds are at their worst. 6 American owned CL-215s operate for various State and Federal agencies. Critics of scoopers in the US claim that there is not enough suitable water in fire prone states. CL-215s have been employed with success in North Carolina, Minnesota, Michigan, Wisconsin, Washington, Alaska, Northern Idaho, and Montana.
French "Sécurité Civile" owns the entire Canadian CL-xx series, a handful of Grumman Trackers and some Russian helicopters, French version more exhaustive. Their pilots are usually recruited amongst the best pilots from "l'Armée de l'Air", usually from "Aéronavale" (Navy pilots on aircraft carriers) or acrobatic teams like "La Patrouille de France". It is a highly risked job that requires very skilled aerial fighters.
Another amphibian is the Beriev Be-200. It can carry a maximum payload of about 3,170 gallons (12,000 litres) of water, making "scoops" in suitable stretches of water in 14 seconds.
Some water-dropping aircraft carry tanks of a guar gum derivative to thicken the water and reduce runoff.
Helicopters can hover over the fire and accurately drop water or retardant. The S-64 Helitanker has microprocessor-controlled doors on its tank. The doors are controlled based on the area to be covered and wind conditions. Fixed-wing aircraft must make a pass and drop water or retardant like a bomber. Spotter aircraft often orbit the fire at a higher altitude to coordinate the efforts of the retardant-dropping aircraft. Lead planes fly ahead of larger airtankers to mark the trajectory for the drop.
Water is often dropped directly on flames because its effect is short-lived. Fire retardants are typically dropped ahead of the moving fire or along its edge and may remain effective for two or more days. This can create an artificial firebreaks where the terrain is too rugged or remote for ground crews to cut fireline.
Helicopters are also used to deliver firefighters or ignite backfires and controlled burns. A driptorch slung beneath the helicopter (helitorch) can be used for this purpose. Another device called a Delayed Aerial Ignition Device (DAID) can be used, which shoots a stream of flaming "ping-pong balls" into the forest. The small plastic spheres which contain potassium permanganate are individually injected with ethylene glycol or glycerine just before they are ejected from the aircraft. This method's delayed oxidation reaction (which results in vigorous fire in just minutes after mixing the chemicals 
) poses less of a danger to the helicopter than carrying along materials which are already burning. The ping-pong ball system works best in continuous fuels or in areas where a mosaic burn pattern is desired.
Aerial firefighting is almost always used in conjunction with ground-based efforts, as aircraft are only one weapon in the firefighting arsenal. However, there have been cases of aircraft extinguishing fires long before ground crews were able to reach them.
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