Infantry Drills

F-81: Principal Direction of Fire

Previous: F-79: Final Protective Line

F-81. PDF is assigned to a gunner to cover an area having good fields of fire or has a likely dismounted avenue of approach. It also provides mutual support to an adjacent unit. Machine guns are sited using the PDF if an FPL has not been assigned. If a PDF is assigned and other targets are not being engaged, machine guns remain on the PDF. A PDF has the following characteristics:

  • It is used only if a final protective line is not assigned; it then becomes the machine gun’s part of the unit’s final protective fires.
  • When the target has width, direction is determined by aiming on one edge of the target area and noting the amount of traverse necessary to cover the entire target.
  • The gunner is responsible for the entire wedge-shaped area from the muzzle of the weapon to the target, but elevation may be fixed for a priority portion of the target.

Next: F-82: Dead Space and Grazing Fire

Go Back To: U.S. Army FM 3-21.8: The Infantry Rifle Platoon and Squad