1966: A B-52G bomber collides with a KC-135 Stratotanker during mid-air refueling at 31,000 feet over the Mediterranean Sea off the coast of Spain, dropping three 70-kiloton nuclear bombs near the town of Palomares and another one into the sea. The KC-135 was completely destroyed when its fuel load ignited, killing all four crew members. The B-52G broke apart, killing three of the seven crew members aboard. The non-nuclear explosives in two of the weapons detonated upon impact with the ground, resulting in the contamination of nearly a square mile by plutonium. The bomb that fell into the sea was recovered intact after a search lasting more than two months. It's the silver tube seen here in the foreground on the fantail of the submarine rescue ship USS Petrel.