The airplane, without human control, may continue to fly until its fuel is exhausted and then crash. Gradually one becomes more euphoric, belligerent, or disoriented and behaves irrationally, unreliably, and dangerously. The impairment of judgment leaves one feeling just fine and confident in one’s performance. There is a serious degradation of judgment, memory, and thought. When blood oxygen saturation is down from the normal 97% to a dangerous 85%, colors fade and vision dims.
Without supplemental oxygen at sufficient pressure the pilots gradually and progressively lapse into incompetence while maintaining an absolutely euphoric faith in their own ability. Vision would begin to degrade, in particular at night. The retina of the eye is more demanding of oxygen than any other organ of the body - even of the brain itself which demands 30% of the overall supply. In those precious minutes, the most insidious effects of hypoxia would sneak in, affecting the eyes and brain. The pilots may lose precious minutes looking for a false alarm, instead of immediately donning their oxygen masks. In contrast, a slow depressurization of an aircraft cabin may be not recognized until an automatic alarm sounds and oxygen masks deploy for passengers. Items (and human beings) could be sucked outside the aircraft as happened on the Aloha Airlines B-737 in 1988. Dust and debris will be picked up and rush toward the opening where the pressurized air is rushing out. This may be preceded by a loud popping sound. It is accompanied by a good deal of noise as the higher pressure air in the cabin rushes out until the pressure equalizes with the external ambient pressure. This is one of the reasons we fly in pressurized airplane cabins.Ī sudden failure of a pressurized cabin is generally very dangerous but immediately recognizable.
At a certain point we get oxygen starvation, or hypoxia. The higher we climb into the atmosphere surrounding Earth, the lower is the partial pressure of oxygen in the alveoli. the pressure of the oxygen component of the gas mixture) is 14% (160 mmHg) when the air we breathe is at the usual 1 atmosphere (760 mmHg), at sea-level. Usually the partial pressure of oxygen in the alveoli (i.e. The oxygen from air passes into our bloodstream through small sacs in our lungs called alveoli. Hypoxia is a phenomenon that receives a lot of attention in aerospace medicine. Too much and anything can become flammable, too little and you get deadly hypoxia resulting in impaired judgment at the precise time it is most needed.Ĭlick to see the physiological effects of hypoxia (Credits: Mayo Clinic). In the operation of aerospace and other systems, oxygen is a friend or an enemy depending on quantity.
Should inspections reveal cases of cracks, in particular on B-777 variants structurally identical to that of the Malaysian Airlines Flight MH370, the slow decompression hypothesis would appear to be an increasingly likely explanation.
#Helios 522 crack#
For the latter case it should be noted that following the discovery of a 40 cm crack on a B-777 on 6 March, just two days before Flight MH370’s disappearance, the FAA issued an Airworthiness Directive requiring inspection of B-777 fuselages for cracks at an antenna location that they said could lead to decompression. The slow decompression could be due to an operational error, as was the case for Helios Flight 522, or because of structural failure. The apparent erratic conduct of flight MH370 and the disabling of some communication equipment could be explained either by impaired pilot judgment typical of hypoxia (oxygen starvation) triggered by a slow cabin decompression, or because of the intervention of someone onboard with limited flight piloting experience who may have tried to replace the hypoxia incapacitated crew. After its last communication Flight MH370 is thought to have crossed back over the peninsula (Credits: Wikimedia user Sailsbystars).
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