Soyuz 18 was a Soyuz spacecraft launched by the Soviet Union but which failed to achieve orbit due to a serious malfunction during launch. The crew consisted of commander Vasili Lazarev, an Air Force major, and flight engineer Oleg Makarov (civilian). April 5 is the 95th day of the year in the Gregorian calendar (96th in leap years). ... 1975 was a common year starting on Wednesday (the link is to a full 1975 calendar). ... UTC also stands for the University of Tennessee at Chattanooga Coordinated Universal Time or UTC, also sometimes referred to as Zulu time, the basis for civil time, differs by an integral number of seconds from atomic time and a fractional number of seconds from UT1. ... The Baikonur Cosmodrome (Russian: Космодром Байконур, Kosmodrom Baykonur), also called Tyuratam, is the worlds oldest and largest working space launch facility. ... April 5 is the 95th day of the year in the Gregorian calendar (96th in leap years). ... 1975 was a common year starting on Wednesday (the link is to a full 1975 calendar). ... For the republic in Russia, see Altai Republic. ... Soyuz TMA-6 spacecraft approaching International Space Station Soyuz 19 spacecraft as seen from Apollo CM Soyuz spacecraft of the Apollo Soyuz Test Project (ASTP) Early 7K-OK Soyuz at National Space Centre, Leicester, England Soyuz (Союз, union) is a series of spacecraft designed by Sergey Korolev for the Soviet Union... Vasili Lazarev Vasili Grigoryevich Lazarev (Russian: Василий Григорьевич Лазарев; February 23, 1928 – December 31, 1990) was a Soviet cosmonaut who flew on the Soyuz 12 spaceflight as well as the abortive Soyuz 18a launch. ... Oleg Grigorievich Makarov (Russian: Олег Григорьевич Макаров; January 6, 1933 – May 28, 2003) was a Russian cosmonaut. ...

The Soyuz 18 mission was supposed to be the second mission to take cosmonauts to the Soviet Salyut 4 space station. Both cosmonauts were on their second mission; they had flown their first mission together, Soyuz 12 in September 1973 to test a new type of Soyuz spacecraft. Salyut 4 (DOS 4) was a Salyut space station launched on December 26, 1974 into an orbit with an apogee of 355 km, a perigee of 343 km and an orbital inclination of 51. ... Soyuz 12 was the test flight of the newly-redesigned Soyuz spacecraft that was intended to provide greater crew safety in the wake of the Soyuz 11 tragedy. ... 1973 was a common year starting on Monday. ...

The launch proceeded according to plan until T+288.6 seconds at an altitude of 192 kilometers, when the second and third stages of the booster began separation. Only three of the six locks holding the stages together released, and the third stage's engine ignited with the second stage still attached below it. The third stage's thrust broke the remaining locks, throwing the second stage free but putting the booster under an unanticipated strain that caused it to deviate from the standard trajectory. At T+295 seconds, the deviation became severe enough that an automatic safety system separated the Soyuz spacecraft from the third stage booster and then separated the orbital capsule of the spacecraft. A kilometre (American spelling: kilometer) (symbol: km) is a unit of length equal to 1000 metres (from the Greek words khilia = thousand and metro = count/measure). ...

At the time when the safety system initiated separation the spacecraft was already pointed downward toward Earth, which accelerated its descent significantly. Instead of the pre-calculated acceleration in such an emergency situation of 15 G (147 m/s²), the cosmonauts experienced up to 21.3 G (209 m/s²). Despite very high overloading, however, the landing parachutes opened properly and slowed the craft to a successful landing after a flight of only 21 minutes. g (also gee, g-force or g-load) is a non-SI unit of acceleration defined as exactly 9. ...

The capsule landed in a rocky area of the northwestern part of China, less than a mile (1.6 km) from the Mongolian border and around 50 miles (80 km) from the Soviet border. The crew was evacuated by Soviet helicopter a few hours after landing, without China being notified. In Brezhnev's time it was not typical to disclose anything about Soviet failures, and so the first publication about the realities of the flight was not made until 1983 in the Army newspaper "Red Banner". 1983 is a common year starting on Saturday of the Gregorian calendar. ...

The Soyuz 18a flight was the only case of a booster accident at high altitude. The mission is referred to in the literature as Soyuz 18-1 or Soyuz 18a, since the following Soyuz mission was also numbered 18 to disguise the accident. Soyuz 18, of the Soyuz spacecraft series, brought cosmonauts Pyotr Klimuk and Vitali Sevastyanov to the Salyut 4 space station where they remained in orbit for 63 days. ...

Crew

• Vasili Lazarev (2)
• Oleg Makarov (2)

Vasili Lazarev Vasili Grigoryevich Lazarev (Russian: Василий Григорьевич Лазарев; February 23, 1928 – December 31, 1990) was a Soviet cosmonaut who flew on the Soyuz 12 spaceflight as well as the abortive Soyuz 18a launch. ... Oleg Grigorievich Makarov (Russian: Олег Григорьевич Макаров; January 6, 1933 – May 28, 2003) was a Russian cosmonaut. ...

Mission parameters

• Mass: 6830 kg

Crew Georgi Grechko (1) Aleksei Gubarev (1) Mission Parameters Mass: 6800 kg Perigee: 185 km Apogee: 249 km Inclination: 51. ... The Soyuz human spaceflight programme was initiated in the early 1960s as part of the manned lunar programme that was intended to put a Soviet cosmonaut on the Moon. ... Soyuz 18, of the Soyuz spacecraft series, brought cosmonauts Pyotr Klimuk and Vitali Sevastyanov to the Salyut 4 space station where they remained in orbit for 63 days. ...