Preparation

For a "Chamber Run".  The hypobaric chambers are used to train aircrew in the signs and symptoms of hypoxia – recognition in themselves and in other crew members.  There are several less drastic ways to carryout this training, for instance using a "normobaric" installation in which only the subject is deprived of oxygen by means of an air-tight mask, but the chamber produces all the drama of a decompression in flight and is a valuable part of the training.

In the Extra photo one of the trainees is having his oxygen checked – both for the pre-oxygenation process to reduce the chance of decompression sickness and for the essential oxygen while "at altitude" in the chamber.