The US was not told in advance of the Soyuz 16 mission. although it was known that a dress rehearsal was to be flown. Only when the Soyuz reached orbit did mission managers inform their American colleagues. NASA was able to put the mission to some use through tracking it and, at the Soviet Union's request, conducting a simulated launch so that the Soyuz crew had something to 'aim' at.

Apart from the initial orbit which was a little higher than planned for ASTP itself, all of Soyuz 16's activities mimicked the flight which was to follow only eight months later. One major activity was raising and lowering the atmospheric pressure in Soyuz. A compromise had to be reached to allow the mission to take place as there was a fundamental difference between US and Soviet spaceraft design. Cosmonauts breathed air at normal atmospheric pressure - astronauts survived in a pure oxygen atmosphere at on-third normal pressure.

Some have suggested that the higher than expected initial orbit may have resulted from a trajectory error and others have suggested that the Soviet Union had chosen it deliberately in order to demonstrate flexibility in controlling a mission through recovering from such an error. Either way the chosen orbit matched that of Cosmos 672 another ASTP simulation mission flown about four months earlier.