SR-71 Facts: 29 Details That Might Surprise You

Sonic Boom Referred To As “The Sound Of Freedom”

The sonic boom made by the SR-71 was used as a signaling device to POW’s in Hanoi, Vietnam. Secret missions of three SR-71s left Japan and crossed paths simultaneously over Hanoi at times throughout the Vietnam War. The sonic boom heard below was a signal to those POW’s that if they had an opportunity to escape – do so now because U.S. Navy ‘Frogmen’ are down river waiting for you. This style of signaling occurred to U.S. Heads of States in other countries as well, specifically Panama. It was a signal to get out.