Launch from the Baikonur Cosmodrome; landing
125 km east of Dzheskasgan.
Following a one day solo flight Soyuz T-4
docked with Salyut 6 on March 13, 1981. The docking with Salyut 6 was delayed
after the onboard Argon computer determined it would occur outside of radio
range with the
TsUP.
The cosmonauts became the
fifth and final
resident crew of the Salyut 6 space station.
In mid-May 1981,
Vladimir
Kovalyonok and Viktor
Savinykh replaced the Soyuz T-4 probe with a Salyut drogue.
This may have been an experiment to see if a Soyuz-T docked to a space station
could act as a rescue vehicle in the event that an approaching Soyuz-T equipped
with a probe experienced docking difficulties and could not return to
Earth.
Visiting crews were the Interkosmos missions
Soyuz 39 on March 23, 1981 and
Soyuz 40 on May 15, 1981, resulting in
common science research onboard the station. One of the first mission
objectives of this crew was, to unload the earlier launched Progress 12
spacecraft. Meteorological studies from the Bermuda triangle were conducted
too.