Soyuz 7K-T No.39
| Names | Soyuz 18a, Soyuz 18-1, April 5th Anomaly |
|---|---|
| Mission type | Docking with Salyut 4 |
| Operator | Soviet space program |
| Mission duration | 21 minutes 27 seconds 60 days (planned) |
| Orbits completed | Failed to orbit |
| Apogee | 192.0 km (sub-orbital spaceflight) |
| Spacecraft properties | |
| Spacecraft | Soyuz 7K-T No.6 |
| Spacecraft type | Soyuz 7K-T |
| Manufacturer | OKB-1 |
| Launch mass | 6830 kg |
| Landing mass | 1200 kg |
| Crew | |
| Crew size | 2 |
| Members | Vasily Lazarev Oleg Makarov |
| Callsign | Урал (Ural – "Ural") |
| Start of mission | |
| Launch date | 5 April 1975, 11:04:54 UTC |
| Rocket | Soyuz |
| Launch site | Baikonur, Site 1/5 |
| End of mission | |
| Landing date | 5 April 1975, 11:26:21 UTC |
| Landing site | Altai Mountains, Kazakhstan (official) 50°50′N 83°25′E / 50.833°N 83.417°E |
| Orbital parameters | |
| Reference system | Geocentric orbit (planned) |
| Regime | Low Earth orbit |
| Altitude | 192.0 km |
| Inclination | 51.6° |
| Period | 90.0 minutes |
| Docking with Salyut 4 (planned) | |
Salyut program insignia | |
Soyuz 7K-T No.39 (also named Soyuz 18a or Soyuz 18-1 by some sources and also known as the April 5 Anomaly): 192–3 was an unsuccessful launch of a crewed 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 make orbit. The crew consisted of commander Vasily Lazarev, and flight engineer Oleg Makarov, a civilian. Although the mission was aborted and did not accomplish its objective, the craft exceeded common space boundaries and therefore is recognized as a sub-orbital spaceflight, which the crew survived. The crew, who initially feared they had landed in China, were successfully recovered.
The accident was partly disclosed by the normally secretive Soviets as it occurred during preparations for their joint Apollo-Soyuz Test Project with the United States which flew three months later. Lazarev never flew to space again and never fully recovered from the accident; Makarov made two more flights on board a Soyuz (both of which were to the Salyut 6 space station).