What happens if cabin loses pressure

To better understand why airlines need to pressurize their cabins, it is important to clarify the air pressure once the airplane is at a cruising altitude of more than 30, feet. At 35, feet, the air pressure is only about 4 pounds per square inch compared to In simple words, an average human will lose consciousness within minutes if the cabin is not pressurized.

Most airlines are pressurized to maintain consistent air pressure between 11 psi and 12 psi. To avoid dangers associated with sudden changes in altitude, every plane has a pressurized system that replaces interior air with the air outside the cabin.

These outflow valves are usually found in the aft section of the plane, which opens and closes according to the altitude level maintaining constant air pressure inside the cabin. The cabin is pressurized using vents in the engine of an airplane. In modern commercial airlines, a series of vented rotors are present behind the large fans of the engine. These overflow valves are automatically controlled by the onboard computers, but pilots are also able to control these outflow valves.

When the pressure inside the cabin needs to be lowered, the outflow valves open up to allow air. The process is also called bleeding the air inside the cabin. In a controlled manner, the valve is opened and shut to control the air pressure inside the cabin.

The valve continues to function throughout the journey, which means that a fresh cycle of air is bled inside the cabin every 2 to 3 minutes. In some aircraft, the pressure comes from the combustion of the engine. The hot combustion air also protects the airplane engine and wings from ice buildup at high altitude. When a cabin is suddenly depressurized, oxygen masks pop out of the upper sockets to provide oxygen supply to passengers.

History of Flight. Virtual Space. Like this article? Comment on this Story. Last Name. First Name. Address 1. Address 2. Enter your email address. The symptoms of hypoxia depend on the air pressure, the amount of oxygen and the rate of depressurization. In a slow depressurization at an altitude of 15, feet without taking additional oxygen through a mask, symptoms include blueness of the lips and fingernails; tiredness, sleepiness and headache; sweating; and mental impairment and poor judgment.

At a cabin pressure of 25, feet or more, there will be increasing mental difficulties as well as dizziness and lightheadedness, visual symptoms such as blurred or double vision, tingling in hands and feet, muscular weakness, lack of coordination and tremors. This soon progresses to unresponsiveness and unconsciousness.

Experimental studies have analyzed how long a person deprived of oxygen and affected by hypoxia is able to cope with an emergency situation. At an altitude of 25, feet, a person can think clearly enough and act effectively for two minutes at moderate activity and three minutes sitting quietly.

These windows of time drop to 45 and 75 seconds at 30, feet and only 18 and 30 seconds at 40, feet. If disaster strikes, always comply immediately with the instructions of the flight attendants.

Using supplemental oxygen until the airplane descends to 10, feet and air pressure within the cabin returns to normal can truly save your life in an emergency. Their column runs Mondays in Bay Area Living. You can write to them at P.