Soyuz 7K-T No.39, (also named Soyuz 18a or Soyuz 18-1 by some sources and also known as the April 5 Anomaly) was an unsuccessful launch of a manned Soyuz spacecraft by the Soviet Union in 1975. The mission was expected to dock with the orbiting Salyut 4 space station, but due to a failure of the Soyuz launch vehicle the crew failed to achieve orbit. The crew consisted of commander Vasili Lazarev, an Air Force major, and flight engineer Oleg Makarov, a civilian.