Launch date – April 5, 1975, launch time 11.03 a.m. GMT, landing at 11.24.27 seconds in the rocky region on the Mongolian-Chinese border (Chinese territory). In-flight time – 21 minutes 27 seconds.

Cosmonauts –

commander Vasily Lazarev, Air Force major,

flight engineer – Oleg Makarov (civilian).

Both cosmonauts were on their second mission. They made first mission together, Soyuz-12 in September 1973 (test of new type of Soyuz spacecraft). This – Soyuz-18 mission was supposed to be second mission on Salyut-4 orbital station (civilian version).

The Souyz-18A flight was the only case of a booster accident at high altitude.

Here is what happened (technically):

- After the launch – flight was standard until 288.6 seconds (altitude – 192 kilometers), when 2nd and 3rd stage of the booster started separation. The 3rd stage engines had already ignited when there was a problem with the 2nd stage separation – only 3 of 6 locks, all of which have to open instantly and free the 3rd stage, functioned properly. The thrust of the 3rd stage broke the still closed locks, and the booster got an unanticipated strain, which caused it to deviate from the standard trajectory. After a certain amount of deviation (at 295 seconds of flight) the safety system devices separated the spacecraft from the 3rd stage – and then, according to the standard procedure, separated the orbital capsule of the spacecraft. Despite very high overloading, the landing parachutes opened properly in time.

- At the time, the safety system initiated – the spacecraft was already pointed toward the Earth. In a normal situation such as this the craft has to be directed toward the horizon. Because it was pointed straight down, its descent was accelerated. That's why instead of the pre calculated overload factor in such situations of 15 G, the cosmonauts experienced up to 21.3 G (recorded data).

The capsule landed in a 'non-standard' region – in a rocky area of the West-Northern part of China – less than a mile from the Mongolian border and around 50 miles from the Soviet border. (Officially – in Altai mountings in the Soviet Union). The crew was evacuated by Soviet helicopter a few hours after landing (the capsule – later the next day) – of course without China being notified.

In Brezhnev's time it was not typical to disclose anything about Soviet Union failures or "non-perfection". The first brief publication about the realities of the flight was not made until 1983 in the Army newspaper "Red Banner".

The reason? – The upcoming joint Apollo-Soyuz mission (May 24, 1975 that same year).
The facts surrounding actual landing place was never published.