It has made recent news that certain symptoms during air travel are due to altitude sickness. This seems simple enough. Air pressure inside common passenger aircraft is equivalent to mild altitude exposure.

People who get symptoms when going to the mountains may get the same headache, tiredness, achyness, and other symptoms of altitude in flight. Drinking alcohol adds to symptoms. Severity of symptoms depends on several things, mainly how high the altitude, and how fast you reach it.

Cabin pressure varies with cruising altitude and type of aircraft. During a flight, the inside of a large commercial passenger air flights may range between 5000 to 9000 feet (~1525-2743 meters), occasionally higher or lower. Small lower planes flying may be able to maintain pressures closer to (or equal to) ground pressures.

How fast aircraft reach these altitudes depends on the flight path, final cruising altitude, type of aircraft, and other factors. Some of my commercial pilot friends say they will pressurize the cabin far more gradually when they see babies onboard, so that they (the babies) cry less as pressure changes around their ears. Pressure change on the ears is not altitude sickness, just simple air volume change. Earplugs do not prevent this problem, and can make it worse in some situations. Future posts can cover why.

Susceptibility to altitude sickness does not seem to be affected by better or lesser physical conditioning, or any kind of fitness or physical training. It is still a hugely interesting topic to understanding how the body reacts to and works at altitude, why certain interventions work or don't, and how soon you can fly after going scuba diving - important to risk of decompression sickness.

Reader Bill, athlete and pilot, writes, "Regulations require no more than a 10,000 foot cabin altitude (3048m) be maintained for commercial passenger flights. Anyone not acclimatized to altitudes between 7 to 10 thousand feet (~2-3 thousand meters) will feel some symptoms of a mild hypoxia, surely after several hours or/and a couple stiff drinks."

The next post tells more about altitude sickness on flights and more interesting issues and a few proposed cures -Altitude Sickness, Viagra, and Bubbles on Flights.