Depressurization

Depressurization is a rapid loss of atmospheric pressure due to damage of fuselage construction when the air inside the aircraft becomes as thin as outside and thus not appropriate for breathing.

Pressurization problems can be caused by:

• Technical reasons ( malfunctioning of the air-conditioning system, electrical system failure, engine failure because engine supplies the work of air conditioning system , metal fatigue, glass fatigue )

• Outside factor (bird strike on a windscreen on high level, detachment of engine that can damage the fuselage, encountering adverse weather conditions, such as turbulence, lightning strike that can cause significant damage of the construction of the aircraft)

• Human factor (explosion of bomb, shooting, not properly closed door, poor maintenance service before departure)

• Any damage to the system could result in a leakage and consequently a rapid loss of cabin pressure.

Pressurization problems can cause an immediate danger to the aircraft, as the reduction of the cabin pressure will affect the crew and the passengers. The time during which people can retain consciousness without oxygen depends on the altitude flown, the size of the oxygen leak and the dimensions of the fuselage. It can vary from 4 to 30 seconds.

• There are two types of depressurization: rapid (explosive) and slow (gradual).

  • A rapid decompression is a drop in cabin pressure in a matter of seconds. It occurs faster than the lungs can decompress the air. Pilots and passengers are short of time to don the oxygen masks, otherwise they will faint.

  • A slow decompression is a gradual change of cabin pressure. It is complicated to determine it without automatic visual and aural warning system All of them are very dangerous as during explosive and rapid depressurization pilots are pressed of time to react while during slow one they can not even notice it and faint. Rapid decompression is easy to recognize as it is accompanied with a loud bang, sudden fogging of the air. During decompression at high altitude the temperature inside the aircraft will plummet to the ambient outside temperature with the danger of frostbite. So cabin pressure will instantly drop well below the freezing point while moisture in the air condenses to form of thick fog. Slow depressurization also poses the hazard as the pilots can not notice it and thus faint.

In all these critical conditions crew will have to retrain consciousness by donning the oxygen mask and initiating an emergency descent.

So, people can suffer from

• Hypoxia ( condition of oxygen starvation in the human’s body that can lead to sluggish thinking, dimmed vision, impaired motor skills- not able to coordinate body movements, loss of consciousness and even death)

• Decompression sickness (disease caused by the rapid loss of pressure of inhaled air mass which being dissolved in the blood starts producing bubbles that block the bloodstream. It can result in paralysis and death)

• Altitude sickness (disease state which is connected with oxygen starvation due to low partial oxygen pressure in the air at high altitudes; it can cause fatigue, nausea, sleepiness, dehydration of the body)