| On June
26, 2001, pilots representing West Houston’s Flight School, Ground
School and Civil Air Patrol participated in high altitude flight
physiology training and high altitude chamber "ride". The class was
conducted at the NASA Neutral Buoyancy Lab located on Ellington Field (EFD)
in Houston Texas. Participants included Michael Cauthen, Jacques Ardoin,
Sean Salter, John McGough, Don Fisher, and Randy "Chip" Dale. The
training lasted throughout the full day, with the morning being spent in
classroom instruction, and the afternoon reviewing equipment, procedures
and the chamber ride itself.
The purpose of the training was
to understand and experience first-hand, the effects of high
altitude flight on the human body. At altitude, although the ratio
of gasses (oxygen, nitrogen, and others) in the atmosphere remains
the same, ambient pressure decreases. With this decrease in
pressure, the body is not as efficient in the transfer of oxygen and
carbon dioxide within the lungs. In addition, the decreased density
of these gases results in less oxygen being available in each
breath. This decrease of oxygen in the blood is known as hypoxia.
During the classroom portion of
the training, attention was given to the symptoms and reactions to
hypoxia, with particular focus on aircraft, pilots, and the ability
to perform the duties of Pilot-In-Command. There are many symptoms
of hypoxia, and they can vary from person to person. These might
include lightheadedness, tingling of the skin, decreased field of
vision, bluing of the lips and/or fingernails, and headache,
eventually leading to sleepiness, impaired judgment, and euphoria,
and ultimately resulting in loss of consciousness.
After lunch, participants were
then briefed on the pressurization systems, the breathing equipment
to be used in the chamber, and the flight profile. Each person was
then fitted with a "soft helmet" incorporating the breathing mask,
intercom and associated connectors. They were then led to the high
altitude chamber for their flight. The flight began with a thirty
minute "pre-breathe" of pure oxygen at sea level pressure, to
saturate the blood with oxygen and expel excess nitrogen and carbon
dioxide. This procedure would slow the effective time of the
hypoxia, allowing more time to observe the symptoms and effects.
The door of the chamber was then
closed, and the internal pressure decreased to simulate a climb of
5000 feet per minute, to FL250 (25,000 feet). Upon reaching their
operating altitudes, participants removed their masks and began a
written test. The test included tasks as simple as writing your
name, basic math problems, memory questions, and connect the dots.
Most participants behaved and performed normally during the first
two to three minutes. Between three and five minutes however,
participants begin to experience various symptoms of various degree.
Some participants completed the full five minutes with only minimum
effects, while others were barely able to function and required
assistance to re-establish their breathing functions. At five
minutes, all masks were returned, and the chamber gradually returned
to sea level pressure.
The training then continued with
a rapid decompression demonstration. Two participants at a time were
then placed into a smaller, auxiliary chamber. The main chamber was
again "flown" to an altitude of 25,000 feet, while the smaller
chamber climbed to a level of only 8,000 feet. With the opening of a
single valve and without warning, the pressures between the two
chambers equalized at an altitude of approximately 21,000 feet
within one to two seconds. The chambers instantly filled with a fog
due to condensation in the de-pressurized air. This procedure gave
pilots a chance to simulate a sudden loss of cabin pressure, and
demonstrated the importance of being familiar and prepared with
onboard emergency equipment.
At the end of the day, it was
agreed that the training was very interesting and valuable to pilots
of any experience level. Anyone wishing to participate in this same
program should contact their Flight Standards District Office (FSDO)
and request an application for the NASA High Altitude Flight
Physiology training. The class is free of charge and available to
any person, with an FAA medical exam less than one year old, and
meeting typical military height/weight standards. The classroom
portion may be attended by those not meeting the medical standards.
For more information on the
physiological effects of flying, consult FAA Advisory Circular AC
67-2, "Medical Handbook For Pilots". |
