Fox.

About Fox

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 NATO phonetic designation for the letter "F", which is short for "fire". A fighter pilot announcing that a weapon has been fired is intended to help avoid friendly fire, alerting other pilots to avoid maneuvering into the path of the munition.