Northern Prairie Wildlife Research Center
There are three basic kinds of prescribed fires: (1) backing, (2) head, and (3) flank fires.
Backing fires are generally the easiest way to burn. Flame lengths are shorter, rate of fire spread is slow, and smoke density is generally less than in head or flank fires. Backing fires burn hotter at the ground surface and do a better job of total fuel consumption than head or flank fires. Overall burn costs per acre will be higher, however, because of the longer time to complete the burn.
Backing fires work best with wind velocities of 6-19 km/h (4-12 mph) from a constant direction. Some disadvantages are the time required and the need for interior firelines at frequent intervals (usually every 150 to 300 meters) to speed up the burning of a large or long area.
Burning downward on slopes has an effect similar to backfires in flat country.
Because head fires burn faster than other kinds of fires, lower overall burn costs can be expected per acre of burn. Containment becomes more critical, however, as wind speed and fuel quantity increase.
You must be absolutely sure the fire will not escape. Burn out a strip downwind with a backfire wide enough to control the head fire.
Flank fires are often used to secure the flanks of a head fire as the head fire progresses. This method of firing can stand little variation in wind direction and needs expert crew coordination and timing.