Soyuz 18a

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**Soyuz 18**
Mission statistics
Mission name:	Soyuz 18
Call sign:	Урал (Ural - "Ural")
Number of crew members:	2
Launch:	April 5, 1975 11:04:54 UTC Baikonur
Landing:	April 5, 1975 11:26:21 UTC Altay Mountains
Duration:	21 min, 27 s
Number of Orbits:	None

Soyuz 18a 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).

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.

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.

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.

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 rare to disclose anything about Soviet failures, and so the first (Soviet) publication about the realities of the flight was not made until 1983 in the Army newspaper "Red Banner".^{[citation needed]}

Details about the abort became known in the West much earlier, however, as it occurred during preparations for the joint ASTP mission, and the Soviets had to inform the Americans what had happened. (There was even a U. S. Congressional Inquiry regarding this failure and several others.) It was revealed that the booster used had been an older model than that planned for use for the joint mission that July. In the report the Soviets made to the Americans, the abort was referred to as "the April 5th anomaly"; and as this was the only term the Soviets ever used for the incident, it became the 'official' designation for years afterwards.

The Soyuz 18a flight has been the only case (as of 2006) of a manned 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 (in May, 1975) received the name Soyuz 18 as the Soviets only gave numbers to successful launches.