A missile approach warning system (MAW) is part of the avionics package on some military aircraft. A sensor detects attacking missiles. Its automatic warning cues the pilot to make a defensive maneuver and deploy the available countermeasures to disrupt missile tracking.

Radar warning receiver (RWR) systems detect the radio emissions of radar systems. Their primary purpose is to issue a warning when a radar signal that might be a threat is detected, like a fighter aircraft's fire control radar. The warning can then be used, manually or automatically, to evade the detected threat. RWR systems can be installed in all kind of airborne, sea-based, and ground-based assets such as aircraft, ships, automobiles, military bases.