Kármán line
As of the launch of Blue Origin NS-16 on 20 July 2021, there have been 349 human spaceflight launch attempts. Two missions did not cross either the Kármán line or the U.S. definition of space and therefore do not qualify as spaceflights. These were the fatal Challenger disaster, and the non-fatal aborted Soyuz mission T-10a. Two aborted missions did cross either the Kármán line or the U.S. definition of space. These were the non-fatal aborted Soyuz mission MS-10 which did not reach the Kármán line but did pass the 80 km (50 mi) line. The other was the non-fatal Soyuz mission, 18a which crossed the Kármán line. Four missions successfully achieved human spaceflight, yet ended as fatal failures as their crews died during the return. These were Soyuz 1, X-15 flight 191, Soyuz 11, and the "Columbia" disaster. Uniquely, Soyuz 34 was launched uncrewed to the Salyut 6 space station, to provide a successful return vehicle for the crew of Soyuz 32. Fourteen of these flights reached an apogee beyond , but failed to go beyond , so therefore do not qualify as spaceflights under the FAI definition.