Why Do Pilots Wear Oxygen Masks When They Fly At Very High Altitudes?

At higher altitudes, oxygen is lessened and it is important for these pilots to breath well in order to fly the plane properly. The brain of the pilots needs oxygen too and this gray matter needs to function well for these airmen to keep the whole aircraft safe together with all the people on board that flying metal!

Hello

The higher your go, the thinner the air and thus the thinner the Oxygen levels. Once you get to a height of 10,000 feet, the Oxygen levels are too low for a person to function and by going higher, could even cause death. Since there are lots of aircraft that can fly well over 10,000 feet  the pilots would need to wear an Oxygen mask.

I hope this answers your question

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Pilots must wear oxygen mask when flying at high altitudes because of the lack of oxygen.  Approx. 71% of the atmosphere is nitrogen and 21% oxygen.  The other 8% doesnt really matter in this case.  If you look on the Periodic table of elements Row 2 column VI and VII, oxygen  O2 is slightly more massive than nitrogen  N2 and in this case slightly denser than air, which is mostly made of nitrogen.  Therefore at high altitudes little to no oxygen may be present requiring a SCBA (self contained Breathing Apparatus).  Hope this helps.

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Above 12,500 feet over 30 min. The FAA requires Oxygen for the air gets thinner above there!

At high altitude there is less oxygen so they wear oxygen masks while flying at very high altitude.

Above 10,000 ft, their is not enough oxygen in the air to allow humans to remain mentally sharp.  The oxygen mask assures pilots that they won't black out from lack of oxygen and crash their airplanes.

They want to be alive when they again make contact with Terra Firma!
Without sufficient percentage of oxygen being available in the breathing atmosphere that they would be operating in, 21.8 ppm is normal at the surface of earth, their brain would close down to 'entrap' oxygen in the brain's arteries, otherwise they go unconscious, followed by a crash landing on return to the earth's surface!