Titan II Missile Silo 374-6 accident
September 19, 1980 – An United States Air Force repairman doing routine maintenance in a Titan II ICBM silo in Arkansas drops a wrench socket which rolls off a work platform and falls to the bottom of the silo. The socket strikes the missile, causing a leak from a pressurized fuel tank. The missile complex and surrounding area is evacuated and eight and a half hours later, vapors within the silo ignite and explode with enough force to blow off the two 740-short ton (670 t) silo doors and hurl the two megaton W53 warhead 600 feet (180 m). The explosion kills an Air Force specialist and injures twenty-one other USAF personnel.