Flank fire

Flank fires (or flanking fires) are designed to burn into the wind, but at an angle to the wind direction. This results in a greater rate of spread and intensity than a backing fire but less than a head fire. On prescribed burns, flank fires are set from an established line to secure the flanks (sides) of the burn unit after the backing fire line is secure and before the head fire is ignited. They can also be used to burn out the interior of a burn unit faster or moderate fire intensity to match the burn objectives or fire behavior conditions.