Excerpt from Air Warriors by Douglas C. Waller, plus links to reviews, author biography & more

A slow leak in an aircraft cockpit or cabin might reduce air pressure, causing an aviator to become hypoxic. Cocky pilots often thought they were supermen and would not admit it. If they were lucky an air traffic controller would notice their slurred speech and order them to strap on their masks. One of the biggest causes of hypoxia was hotdogging in the cockpit. It happened, despite constant lectures and warnings from superiors. In 1989, two F-14 aviators flying at a high altitude over Arizona lost consciousness and plummeted to their deaths. They had removed their helmets and oxygen masks and donned cloth garrison caps so buddies in a nearby plane could photograph them saluting.

Students were run through the hyperbaric chamber to learn the particular symptoms each would develop at the onset of hypoxia so they could correct the problem before blacking out. The instructors also hoped it would throw a healthy scare into the would-be aviators not to play around in their aircraft.

McKinney plopped into one of the plastic bucket seats in the chamber. It held seventeen students at a time. To his left was a black control panel with colored knobs and switches that regulated the air flow into his oxygen mask and enabled him to communicate with technicians outside the chamber. The students faced each other in two rows. At one end inside the chamber sat an instructor wearing a flight helmet with its oxygen mask attached to a gray hose dangling from the ceiling. Two other instructors also wearing helmets and oxygen masks paced up and down the aisle between the students watching for problems.

The exercise was carefully regulated to prevent accidents, but there were risks. Pregnant women or students with ear or teeth problems were not allowed in the chamber. The sudden exposure to lower pressure could be hazardous to sinuses and cavities. Pilots also were not allowed to be blood donors and discouraged from smoking; both compounded the hypoxic condition at high altitudes. Students were closely monitored for an hour after visiting the chamber for signs of any complications, such as the bends, which resulted from nitrogen bubbles forming in joints or bones when the chamber decompressed. Often, they also woke up the next morning unable to hear their alarm clocks because of "postflight ear block," caused by oxygen saturating the inner ear.

The instructors, with oxygen masks already strapped to their faces, began pantomiming orders. McKinney plugged in the jack from his communications cord to the console so he could receive directions from technicians outside. A microphone was implanted in his oxygen mask along with tiny receivers in the earpieces of his helmet. Next he attached the gray oxygen tube from his mask to the air outlet, then cinched the mask straps to the sides of his helmet so the mask fit snugly, creating a tight seal over his cheeks. He flipped the air regulator switch into the positive position. The airflow indicator blinked red, then white as he began to breathe.

The mask felt constricting. Every time he took a breath it sucked his cheeks like a plunger. He'd have to get used to this mechanical act of breathing. He flipped the switch so 100 percent oxygen flowed into his mask. It tasted cool and rich. His lungs felt invigorated.

He hit the test button that force-fed the oxygen from the tube to simulate what he might experience at high-altitude flight. His mask ballooned. It was a rush, as if someone had stuck a blow dryer into his mouth, ramming air into his lungs. He couldn't inhale it fast enough. Every time he tried to exhale it seemed that more oxygen was forced down his throat. Pilots learned a pause-breathing technique -- inhale for three to five seconds, exhale for three to five seconds, pause three to five seconds -- in order to avoid hyperventilating from taking in pressurized oxygen.

The pleasant voice of Susan Redding, a hospital corpsman operating the chamber's controls from the outside, piped into his earpiece. She sounded like an airline stewardess, reciting instructions to passengers.

Copyright © 1998 by Douglas C. Waller