ALARM

ALARM, short for Air-Launched Anti-Radar Missile, is an air-launched weapon designed to destroy ground-based air defence radars and the radars of surface-to-air missile batteries, so that attack aircraft can fly through hostile defences. It homes on radar transmissions and follows them down to their source. Its distinctive feature is an optional loiter mode: the missile climbs to about 40,000 feet, deploys a parachute and descends slowly while its seeker searches for any radiating emitter. When it finds a target it releases the parachute and falls onto it. This answers the usual defence of switching a radar off when a missile is detected, because the missile remembers where the emitter was and still attacks that spot. Direct firing modes also let it be launched straight at a surface-to-air missile site once the emitter has been located. A Tornado GR1 can carry seven of them. The source says it entered service in the early 1990s and proved very effective in the Gulf War.