They can be fitted with tanks or buckets to deliver water and fire retardant to the fireline. Large, heavy-lift helicopters can fill their water tanks with a snorkel that siphons water from lakes, rivers, or other sources. Smaller helicopters carry water in buckets that hold between 100-400 gallons of water. Each bucket has a release valve on the bottom controlled by the helicopter crew. When the helicopter is in position, the crew releases the water to extinguish hot spots.
Helicopters also deliver firefighting crews called helitack crews to fires for initial attack. Some helitack crews are trained to rappel from helicopters to fires in remote locations. All Forest Service helicopter operations follow Federal Aviation Administration and interagency standards, policies, and safety procedures.