Fox (Code Word)
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.
There are four variations of the Fox brevity word, with a number added to the end of Fox to describe the primary type of sensors the launched munition possesses (if applicable). In addition, a separate brevity word for gunfire exists and is grouped with the four Fox codes for convenience.
Fox One – Indicates launch of a semi-active radar guided missile (such as the AIM-7 Sparrow)
Fox Two – Indicates launch of an infrared-guided missile (such as the AIM-9 Sidewinder)
Fox Three – Indicates launch of an active radar guided missile (such as the AIM-120 AMRAAM)
Fox Four/Guns – Indicates air-to-air or air-to-surface cannon fire.