The principle of the existing reliability level of space engineering, and first of all, of rocket-launchers is laid into the milestone of the cosmonauts training (the successful launch of "Soyuz" space vehicle is close to 1, but it is less than 1), that causes a possible landing of space crews outside the regular landing site.

The forced (emergency) landing can take place on any unpopulated difficult accessible terrain in various climatic and geographical regions or in the aqueous areas of the World (global) ocean.

Search, rescue and evacuation of the space vehicle crews is assigned to a search and rescue complex.
However, search operations can be hampered by difficult meteorological and geographical conditions in the region of emergency landing.

Therefore, the crew might have to stay for a long time in conditions of independent (autonomous) existence, and its favorable outcome will mainly depend on its ability to survive.

Survival implies active, expedient actions to be undertaken in order to preserve a life, health and work capacity under conditions of unfavorable factors of the environment at a site of forced (emergency) landing.