medical certificate can normally sign up and receive altitude training from several commercial facilities and a very limited availability from a government facility. 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 10,000 ft. 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 maneuver. If they perform the valsalva during ascent, they risk suffering barotrauma of the ear. This is because the ears are susceptible to Boyle's Law. There are also other profiles, such a hypoxia training profile, where the chamber ascends to an altitude of 25,000 ft. Upon arriving at 25,000 ft, 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 will understand 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 8,000 ft to 22,000 ft within 10 to 20 seconds, to simulate the loss of a cabin door. For fighter pilots this is done from an altitude of 25,000 ft to 43,000 ft within 5 seconds which simulates the loss of a fighter aircraft's canopy. Hypobaric chambers are also finding increasing use as a means of improving athletic performance. Since the human body adapts to extended mild hypoxia by increasing the quantity of red cells in the blood and this raises aerobic performance, athletes sleep in them as part of their training regimen. This has roughly the same effect as training in high altitudes, but the use of hypobaric chambers plays into the controversial issue of enhanced athletic performance. Mika LaVaque-Manty asks in his book, "Are hypobaric chambers, which simulate high-altitude conditions, a natural way to improve your body?" This hints that the hypobaric chambers use can be likened to blood doping and thus be deemed an unfair athletic advantage. This could lead to a ban on hypobaric chambers for athletic training. Institutions with hypobaric chambers terraXcube, Eurac Research, accredited laboratory for environmental