To start building a fire line, a crew of "tree fellers" walks ahead and cuts down the trees along a belt that is as close to the fire as possible; this will become the fire line. If the fire has fingers, the crew will make a straight line ahead, keeping the fingers inside the fire line instead of trying to follow the fingers. The tree fellers also avoid steep slopes and use natural barriers as part of the fire line.

After the tree fellers come the "sawyers," cutting up the trees on the ground and moving the pieces out of the fire line. They also clear logs, branches, and brush. Following the sawyers, crew members burn out the corridor, removing all the roots and brush, making sure to cut out the section of each root that crosses the...