Fox is a brevity code used by NATO pilots to signal the simulated or actual release of an air-to-air munition or other combat function. Army aviation elements may use a different nomenclature, as the nature of helicopter-fired weapons is almost always air-to-surface. 'Fox' is short for 'foxtrot', the phonetic designation for the letter 'F', which is short for 'fire'. The radio call announcing that a weapon has been fired is intended to help avoid friendly fire, cuing other pilots to ensure that they do not maneuver into the path of harm.