After the problems with Cosmos 186/188, the State Commission would not agree to an attempted manned flight. They demanded an incident-free unmanned rendezvous and docking mission first.
The launch of the active spacecrafat in the docking exercise, Cosmos 212 (7K-OK(A) s/n 8), came first. The launch was almost been scrubbed two hours before launch, when data from the spacecraft indicated failure of the primary orientation engine controller. However it was not clear if the system had actually failed, or if this was just an incorrect signal. Since there was a backup system aboard, it was decided to launch anyway. The decision to go came at 12:34, just 26 minutes before the launch time. Soyuz s/n 8 was launched into space at 13:00 local time. At 14:30, at the beginning of the second orbit, it began maneuvers preperatory to rendezvous with s/n 7. Ground control received 8 items of telemetry from the spacecraft. On the third orbit the spacecraft oriented itself to the sun. Soyuz s/n 7 and 8 were the first manned spacecraft fitted with the 76K infrared horizon centre, which established local horizontal for the spacecraft. Ion sensors were used to detect the direction of motion, as had been proven on the Zenit spy satellites. Using these sensors, s/n 8 accomplished its first rendezvous manoeuvre on its fifth orbit, raising first its apogee by 6 km, then its perigee by 22 km.
Cosmos 213 launched at 09:36 the next day, and Cosmos 212 immediately began the active rendezvous phase. By 12:54 the two spacecraft were 33 m apart, closing at 2 m/s - then ground lost contact with them. There was tremendous relief at 13:21 when the Alma Alta tracking station received a positive parameter 2 in the telemetry - confirming hard dock and electrical connection between the two craft. A loud "Ura!" echoed through the control centre. The docking had been accomplished despite 14 of the 28 orientation thrusters being inoperative due to the controller failure. The two ships spent 3 hours and 50 minutes docked, and then separated. S/n 8 was put through tests of the alternative sensor systems. Another orbital change was made on the 51st orbit using the new infrared horizon scanner and the ion sensors for orientation. Another manoeuvre was made on the 52nd orbit using only the solar sensors. As a backup in case of failure of the ion sensor, it was planned that a cosmonaut on earth would use television of the Vzor optical orientation device to orient the spacecraft in the direction of movement. This was tested as well. Cosmos 212 reentered without a problem on 19 April.