Fox is a brevity code

Brevity code

Multiservice tactical brevity codes are codes used by various military forces. The codes procedure words, a type of voice procedure, are designed to convey complex information with a few words.-American/NATO codes:...

 used by NATO pilots to signal the simulated or actual release of an air-to-air

Air-to-air missile

An air-to-air missile is a missile fired from an aircraft for the purpose of destroying another aircraft. AAMs are typically powered by one or more rocket motors, usually solid fuelled but sometimes liquid fuelled...

 munition or other combat function. Army aviation

Army aviation

Army Aviation refers to aviation-related units of a nation's army, often described as an air corps. These units are generally separate from a nation's dedicated air force, and usually comprise helicopters and light support fixed-wing aircraft....

 elements may use a different nomenclature, as the nature of helicopter

Helicopter

A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

 fired weapons is almost always air-to-surface

Air-to-surface missile

An air-to-surface missile is a missile designed to be launched from military aircraft and strike ground targets on land, at sea, or both...

. 'Fox' is short for 'foxtrot', the phonetic

Phonetic alphabet

Phonetic alphabet can mean:* phonetic transcription system: a system for transcribing the precise sounds of human speech into writing.** International Phonetic Alphabet : the most widespread such system...

 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

Friendly fire

Friendly fire is inadvertent firing towards one's own or otherwise friendly forces while attempting to engage enemy forces, particularly where this results in injury or death. A death resulting from a negligent discharge is not considered friendly fire...

, cuing other pilots to ensure that they do not maneuver into the path of harm.

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

Sarh

Sarh is the third largest city in Chad, after N'Djamena and Moundou. It is the capital of Moyen-Chari region and the department of Barh Köh. It lies 350 miles south-east of the capital Ndjamena on the Chari River...

 guided missile (such as the AIM-7 Sparrow

AIM-7 Sparrow

The AIM-7 Sparrow is an American, medium-range semi-active radar homing air-to-air missile operated by the United States Air Force, United States Navy and United States Marine Corps, as well as various allied air forces and navies. Sparrow and its derivatives were the West's principal beyond visual...

)

Fox Two - Indicates launch of an infrared-guided missile (such as the AIM-9 Sidewinder

AIM-9 Sidewinder

The AIM-9 Sidewinder is a heat-seeking, short-range, air-to-air missile carried mostly by fighter aircraft and recently, certain gunship helicopters. The missile entered service with United States Air Force in the early 1950s, and variants and upgrades remain in active service with many air forces...

)

Fox Three - Indicates launch of an active radar guided missile (such as the AIM-120 AMRAAM

AIM-120 AMRAAM

The AIM-120 Advanced Medium-Range Air-to-Air Missile, or AMRAAM , is a modern beyond-visual-range air-to-air missile capable of all-weather day-and-night operations. Designed with the same form-factor as the previous generation of semi-active guided Sparrow missiles, it is a fire-and-forget...

)

Fox Four - Historical term indicating air-to-air or air-to-surface cannon fire. Current usage is Guns