Planned second crew to the first Almaz space station. Cancelled after the loss of control of Almaz OPS 1 (Salyut 2) in orbit.
On 4 July Soyuz 14 docked with the Salyut 3 space station after 15 revolutions of the earth. The planned experimental program included manned military reconnaissance of the earth's surface, assessing the fundamental value of such observations, and some supplemental medico-biological research. All objectives were successfully completed and the spacecraft was recovered on July 19, 1974 at 12:21 GMT, landing within 2 km of the aim point 140 km SE Dzkezkazgan. After the crew's return research continued in the development of the on-board systems and the principles of remote control of such a station.
Soyuz 15 was to conduct the second phase of manned operations aboard the Salyut 3 military space station, but the Igla rendezvous system failed and no docking was made. The two day flight could only be characterised as '... research in manoeuvring and docking with the OPS in various modes, and development of methods for evacuation and landing from space complex in new conditions....' The crew was recovered on August 28, 1974 20:10 GMT. Officially: Conduct of joint experiments with the Salyut-3 orbital scientific station.
Second TKS flight that would have docked with the cancelled Almaz OPS 4 military space station. The spacecraft was instead flown unmanned to Salyut 7 as Cosmos 1443.
Third TKS flight that would have docked with the cancelled Almaz OPS 4 military space station. The spacecraft was instead flown unmanned to Salyut 7 as Cosmos 1686. For that mission the VA reentry capsule was retained but stripped of its heat shield and all recovery equpment. In their place military optical test sensors (infrared telescope and Ozon spectrometer) were installed.