JOINT BASE ANDREWS, Md. –
"In case there is a loss in cabin pressure, yellow oxygen masks will deploy from the ceiling compartment located above you ... breathe normally."
Flight attendants say these words while conducting a safety demonstration aboard an aircraft, informing passengers of what to do in case of an in-flight emergency. The same concept is used for military members who protect and serve the country from 25,000 feet in the air, except the speech is not given while aboard on aircraft, but in the seat of an altitude chamber.
The 779th Aerospace Medicine Squadron aerospace and operational physiology training flight trains aviators and special operations high-altitude parachutists how to recognize physiological stresses and human performance factors associated with military flying. More importantly, they train them how to overcome these challenges.
The flight conducts approximately 15 classes a month to instruct students about the atmospheric physiology, spatial disorientation, decompression sickness, survival, crash and escape and how to recognize signs of hypoxia.
"Hypoxia is the state of oxygen deficiency in the blood and tissues," said Maj. Daniel Gibson, flight commander. "Becoming familiar with the signs and symptoms, and knowing how to react accordingly, is the difference between life and death in the aerospace environment."
These include tunnel vision, air hunger, numbness, mental confusion and other states of disorientation. Students experience hypoxia once they reach 25,000 feet in an altitude chamber, which simulates levels of ascending and descending altitudes.
Before entering the chamber, students are issued a head gear unit and an aviator mask. After verifying the gear is working properly, the students sit in the chamber and breathe 100 percent oxygen for 30 minutes - a process known as denitrogenation.
"As the term suggests, denitrogenation eliminates nitrogen in the body," said Master. Sgt. Jeff Gilbert, NCO in charge of the flight. "A build up of nitrogen in the body can cause serious effects when you reach high altitudes. Breathing supplemental oxygen for a certain period of time removes one-third of the nitrogen from our bodies."
The flight technicians follow a flight profile which illustrates pressurization levels in the chamber. It is essentially a timeline of when and to what altitude to descend and ascend for the duration of the demonstration.
After 30 minutes of breathing 100 percent oxygen, the students ascend to 25,000 feet and drop their mask to experience hypoxia. Half of the class keep their masks on and observe the visual effects of hypoxia while the other half is experiencing the physical effects. After five minutes, they switch.
Technicians have the students watch each other for two reasons, said Tech. Sgt. Dan Kilbride, NCO in charge of logistics. The first reason is so the student can externally see the changes of the body as well as internally feel the effects of hypoxia. The second reason deals with the wingman concept. While onboard an aircraft, if your wingman is showing the signs and symptoms of hypoxia, then you will be able to recognize it and react accordingly.
The journey in the altitude chamber is not over. The next stop on the flight profile is 18,000 feet.
Here, the lights are dimmed, windows are blocked and a night vision demonstration is conducted. The students take off their masks at this altitude to experience the dramatic difference in the sharpness of their vision between flying with and without 100 percent oxygen during night operations.
After the night vision demonstration, the students descend to ground level.
For the students, they return every five years for a refresher course; however, the officers and flight technicians take the journey in the altitude chamber one to four times a month.
Limitations on how often the flight technicians are allowed to fly are in place to reduce the possibility of developing decompression sickness, said Major Gibson.
"The environment created within the altitude chamber is unique and not without risks," he said. "But we are dedicated to the mission to those we serve, and we truly operate at the limit of our operational capability."
The physiology flight is the last stop before aircrew members and special operations high-altitude parachutists take to the sky. The flight trains all branches of the military, the Federal Air Marshals, the Federal Aviation Administration, Civil Air Patrol and NASA.
And sometimes that capability makes the ultimate difference.
"It does not happen often, but when we get an e-mail or phone call from a former student who shares their story about how our training saved their life, the feeling is second to none," said Major Gibson. "It is great a reminder that we really are making a difference with those who we train."
So ladies and gentlemen, please bring your tray tables and seat backs to their upright and locked positions and rest assured knowing the airborne angels who protect and serve the country are properly trained to handle any kind of in-flight emergency.