Launched 26 August 1974, the Soyuz spacecraft arrived at the station, but cosmonautsLev Dyomin and Gennadi Sarafanov were unable to dock because of a fault in the automated docking system. Without sufficient fuel for prolonged attempts at manual docking, the mission had to be abandoned. The crew landed 28 August. Analysis of the launch window was cited by observers for concluding a flight of 19 to 29 days had been planned.
It was later claimed by Soviet authorities that no docking had been intended and that the flight had been undertaken merely to develop techniques for maneuvering near the space station. They also said that a new automatic docking system was tested which would be used on future Progress transport craft.