If you\'ve flown in a commercial airliner, you have heard the flight attendants
ID: 65549 • Letter: I
Question
If you've flown in a commercial airliner, you have heard the flight attendants instruct you that in case of a sudden loss of cabin pressure, oxygen masks will be deployed. At a cruising altitude of 30,000 feet the "oxygen" arrives in your mask at the surrounding atmospheric pressure, which is substantially lower than the atmospheric pressure at sea level. Why does breathing an oxygen-enriched gas mixture help keep you alive at high altitude, when the pressure is so low overall? Can you tell if you're getting enough oxygen, and why is it necessary to put on your own oxygen mask first before helping someone who needs assistance?
Explanation / Answer
In the event that the plane loses cabin pressure while at altitude, the oxygen masks will fall from the ceiling. This is to provide adequate oxygen for the passengers. Imagine yourself on such a plane, traveling with your children or grandchildren. The hatches above the seat open and the masks fall. Your natural inclination would be to get the masks on your children and only then help yourself. In the worst-case scenario, you might black out before you got your child’s mask on. Then your children slip into unconsciousness, and both of you suffer brain damage. The only way to ensure that you can help those around you is to help yourself first, thus the admonition from the flight attendant to “put on your own oxygen mask before helping those around you”.