If you’ve ever traveled by plane, you know that life at 35,000 feet is reasonably comfortable, aside from sitting in the same seat for hours.
The primary requirement for human survival is oxygen. So how can hundreds of people breathe in the same cabin on journeys that last for hours?
Given this fact, traveling in a commercial airplane is not much different from being on land, with ample oxygen on the plane keeping us alive.
We are not talking about emergency oxygen masks that automatically drop in case of cabin pressure drop. How do we breathe so easily on an airplane under normal conditions?
There is natural oxygen in the air
The air at the altitude at which most commercial aircraft operate is actually quite enough to breathe. In other words, there is plenty of air at 35,000 feet and enough oxygen in it.
However, the pressure of the oxygen in that air is too low to be inhaled directly by humans. So how do we breathe on the plane?
How to provide fresh air to passengers on flights
Most commercial airplanes have a mechanism that lets hot compressed air in through their jet engine, then processes that air and transfers it to the passenger cabin.
When an airplane is flying, fast-moving air enters both jet turbine engines. This fast-moving air is compressed as it passes through the layers of fan blades inside the turbine. Some of the hot air is collected through the turbine with the help of the compressor.
However, since the collected air is quite hot, cooling should not be applied. Therefore, the hot air is then cooled and expanded by passing through the heat exchanger.
This cool, filtered air is then distributed into the passenger compartment at a pressure that people can breathe comfortably.
There is also usually an outlet valve at the rear of the cabin that allows ‘used’ air to be expelled from the aircraft, thereby regulating the air quality in the cabin. Thus, the air in the cabin is constantly renewed during long journeys.
In short, the two jet turbine engines you see on either side of the plane not only keep the plane in the air by providing forward thrust, but also help maintain cabin air pressure so that we stay comfortable and conscious throughout our flight.