Identification, Friend Or Foe (IFF)

IFF is primarily a combat identification technique used in air defense procedures to identify approaching aircraft. Typically, IFF is implemented through radio wave or electromagnetic devices that broadcast a specific encrypted signal to the aircraft. If the aircraft responds in a manner deemed as friendly, it is identified as a friend; if it responds inappropriately or not at all, it can be distinguished as a foe. Each airplane is installed with an IFF transponder that responds to all incoming IFF interrogation requests and also defines the intent of the airplane. The IFF system uses two different channels; one is for interrogating the aircraft, while the other for receiving the reply.