The callsign Yantar (amber) was used. The Soyuz 7K-OKS spacecraft was launched on 6 June 1971, from Baikonur Cosmodrome in central Kazakh Soviet Socialist Republic. Several months earlier, the first mission to the Salyut, Soyuz 10, had failed to successfully dock with the station. During the first day of the flight, maneuvers were made to effect a rendezvous with the unmanned Salyut (1971-032A). When Soyuz 11 was 6 to 7 km from Salyut, automatic devices took over and in 24 minutes closed the gap between the two ships to 9 m and reduced the relative speed difference to 0.2 m/s. Control of the ships went from automatic back to manual at 100 m. Docking took 3 hours 19 minutes to complete and involved making the connection mechanically rigid, engaging various electrical and hydraulic links, and establishing air-tight seals before locks could be opened. When the pressure was equalized between the ships, the locks were opened and all three members of the crew passed into Salyut 1. Soyuz 11 successfully docked with Salyut 1 on 7 June 1971 and the cosmonauts remained on board for 22 days, setting space endurance records that would hold until the American Skylab 2 mission in May–June 1973.