Why was the sr 71 blackbird decommissioned?

By the late 1980s the Blackbird was a 1960s design flown by fewer than a dozen airworthy examples. Everything about it was bespoke: the JP-7 fuel that no other aircraft used, a fleet of KC-135Q tankers modified to carry it, titanium airframes that needed specialised inspection after every flight, and spare parts no longer in production. Lockheed's Skunk Works had built 32 aircraft between 1962 and 1968, and twelve had been lost in accidents. Air Force leaders argued that the money spent on the small SR-71 detachment would buy more capability elsewhere, and Congress ended the funding. The last operational flight took place in January 1990; in March one aircraft set a coast-to-coast record on its delivery to the Smithsonian.

The SR-71 was born because the U-2 had become vulnerable and satellites were primitive. By 1990 KH-11 satellites returned digital imagery within hours, while the Blackbird still carried film and radar cassettes that had to be processed after landing. It could not loiter, could not be re-tasked in flight and could not be sent anywhere without a chain of tankers. Its unique strength, penetrating defended airspace at Mach 3.2 and 26,000 m (85,000 ft), mattered less once the Soviet threat receded.

Coverage gaps during the 1991 Gulf War prompted Congress to fund a return: two aircraft were reactivated in 1995 with a datalink for near-real-time imagery. The Air Force never wanted the programme back, its funding was vetoed in 1997 and the aircraft flew their last military sortie in 1998. NASA kept two examples at Dryden for high-speed research until 1999, and unmanned systems such as the Global Hawk, first flown in 1998, took over long-range reconnaissance. Every surviving Blackbird is now in a museum.