On 2 October 1991, Franz Viehboeck launched with Soyuz TM-13 at the MIR space station as part of the Austrian-Russian space project AUSTROMIR-91. The launch took place together with Aleksandr Volkov and Toktar Aubakirov from the Baikonur Cosmodrome.

On the MIR space station, he carried out a total of 15 scientific experiments over a period of six days. On 10 October 1991, he returned to Earth with Soyuz TM-12 together with Anatoli Arzebarsky and Toktar Aubakirov.

So he became the first and so far only Austrian in space.