Strong Corridor

This is a chamber for training in operating at altitude, a hypobaric chamber, one of several; you can see the entrance to the next chamber through the doors.

There is another way for training individuals to recognise lack of oxygen, a preferred method, in which a mask is clasped tightly to the trainee's mouth and nose.  Oxygen is then reduced induce hypoxia to enable the trainee to recognise the symptoms as they occur.