While the mask is off, subjects may be asked to do trivial tasks, such as arithmetic and signing their own name. When such tasks start taking excessive lengths of time to be done or are done poorly, it is usually a sign that the "Time of Useful Consciousness" has been exceeded and that the mask should be replaced. Subjects may also insure that they are able to do tasks such as clear their nose and sinuses easily, as pain from such problems can be a major distraction in an emergency such as rapid decompression.
There are many procedures followed during chamber training for aircrew. Usually new aircrew will undergo a familiarization profile, where the chamber ascends to an altitude of 10,000ft. During the ascent they are instructed on the proper procedure to clear the ears. During ascent, students are asked to yawn and on descent they need to perform the valsalva technique. If they perform the valsalva during ascent, they risk suffering barotrauma of the ear. This is because the ears are suceptible to Boyle's Law.
There are also other profiles, such a hypoxia training profile, where the chamber ascends to an altitude of 25,000ft. Upon arriving at 25,000ft, students are removed from their oxygen supply two at a time, for around 2 to 3 minutes. During this time, they will be asked to complete simple tasks such as copying shapes on a piece of paper. They are asked during the time off oxygen how they feel. After being placed back on oxygen, they see how their judgement was impaired during the time that they were experiencing hypoxia.
The training goes further with rapid decompression profiles, where the chamber is very rapidly ascended from 8,000ft to 22,000ft within 10 to 20 seconds, to simulate the loss of a cabin door. For fighter pilots this is done from an altitude of 25,000ft to 43,000ft within 5 seconds which simulates the loss of a fighter aircraft's canopy.
QT dispersion during hypobaric hypoxia/ alcak basinc ortaminda olusan akut hipoksinin QT dispersiyonu uzerine etkisi.(Original Investigation/ Orijinal Arastirma)(Clinical report)
Aug 01, 2008; ABSTRACT Objective: Hypoxia is one of the major concerns in aviation. Clinical hypoxia has been shown to increase QT dispersion...