https://science.howstuffworks.com/space/aliens-ufos/area-5114.htmHow Area 51 Works. 1962: The first A-12 arrives at Groom Lake. The first test flight takes place two months after the aircraft's arrival to the base. CIA pilots arrive at the base nearly a year later to begin flight training. 1967: The first MiG 21, a Soviet aircraft, arrives at Groom Lake.