High Altitude Parachute Class
Senior Airman Jeylyn Capdevilla discusses the physical effects of the high-altitude chamber Nov. 2, 2010, at the aerospace physiology building at Shaw Air Force Base, S.C. The high-altitude parachute class focuses on human performance at high altitudes and high stress levels. Students take this class before freefall school and as a refresher course every five years. Airman Capdevilla is a 20th Aerospace Medicine Squadron operational physiologist technician. (U.S. Air Force photo/Airman 1st Class Tabatha L. Duarte)
Joint forces unite for high-altitude training



by Airman 1st Class Daniel Phelps
20th Fighter Wing Public Affairs

11/15/2010 - SHAW AIR FORCE BASE, S.C. (AFNS) -- "All right, now go ahead and start counting down from 100 by threes," said Senior Airman Jeylyn Capdevilla, a 20th Aerospace Medicine Squadron operations and aerospace physiology technician, while directing the high-altitude simulation from outside the large air chamber.

"100, 19, 97, 94, 87, 77," said a Navy student.

"Alright, go ahead and correct yourself," laughed Airman Capdevilla.

The Navy student fastened his oxygen mask to correct himself from his hypoxia symptoms. Hypoxia is what happens when there is a lack of oxygen in the blood.

"The danger in becoming hypoxic is if it continues, one can pass out, and if not corrected, it can become life threatening," said 2nd Lt. Carolyn Price, a 20th AMS operations and aerospace physiologist.

This scenario was part of a class for high-altitude freefall parachutists, covering high-altitude physiology and human performance related issues.

Thirteen servicemembers from the Army, Navy, Marines and Air Force arrived at the aerospace physiology building here Nov. 2 to take part in the training.

"This class is important for them because the factors that come into play during high-altitude affect your situational awareness ability and the way your brain works," Lieutenant Price said.

The training was divided into two parts: the classroom session and the high-altitude chamber.

The class goes through the details of the atmosphere, respiration, circulation and what happens to the body at high altitudes, Lieutenant Price explained. It also teaches servicemembers how the body can fail to function in flight at high altitudes.

From there the instructor moved on to explain situational awareness factors that decrease and specific threats, such as visual illusion.

Once the class session was done, the students headed to the room where the altitude chamber is located.  There they had their faces measured and received their oxygen masks.

"The chamber gives the experience of high-altitude affects in a safe environment where people can ensure there are no problems," Lieutenant Price said.

Once the students were seated in the chamber, Airman Capdevilla helped familiarize them with the equipment to alleviate any tension they might have. She also answered any questions about the simulation they were about to take part in.

She took her place at the director's seat after leaving the chamber and gave the students final instructions. She led them in an ear and sinus check to ensure everyone was ready.

At the end of her instructions, she told them to put on their masks.

For the next part of the training the students donned their oxygen masks so they had time to de-nitrogenize before the "flight," Lieutenant Price said. To eliminate all nitrogen from the blood, the body needs no less than 30 minutes of breathing pure oxygen. This process helps trainees avoid decompression sickness from the altitude changes.

When that block was completed, the chamber doors were sealed and cabin's "flight" began.

Once altitude was reached, Airman Capdevilla directed the students to remove their masks.

This allowed them to recognize their developing symptoms of hypoxia, she said. After they began experiencing the onslaught of it, they corrected by putting their oxygen mask back on.

"It's really interesting to see what oxygen deprivation does to people," Lieutenant Price said. "I had one student who came in and got real euphoric. He said he felt like he was in the '60s. Their reactions to hypoxia can be really entertaining."

After several minutes of breathing through the oxygen masks to recover from hypoxia, Airman Capdevilla dimmed down the lights in the vault and the lights outside the chamber were turned off.

"This is done to simulate night flying missions," she explained.

Senior Airman Marion Franco, a 20th AMS operations and physiology technician and chamber observer, passed out giant cards with Z's and several lines of different colors to the participants.

"These charts that have been passed out are going to be for a visual acuity test," Airman Capdeviila said. "In a minute, you will take off your masks again and see how hypoxia affects your vision."

She then directed the students to remove their masks. It did take not long for the servicemembers to recognize the effects and put their masks back on.

"Everything went reddish," said a Soldier about the effect.

"There was a foggy haze, and then everything became sharp after I put my mask back on," explained a Marine.

A couple of the students experienced what is known as the oxygen paradox.

"After the masks have been taken off, the body begins to compensate for that lack of oxygen," said Capt. Michael Armstrong, a 20th AMS operation and aerospace physiologist. "When the mask is put back on again, a rush of oxygen comes back to the body. This can cause a shock to the system and a brief worsening of hypoxia symptoms before they get better."

This section concluded the final portion of their training. Once all the students donned their oxygen masks, the lights came back on and the chamber descended back to regular elevation.

"The chamber gives the students experience going to altitude, pressure breathing and gas volume changes," Lieutenant Price said. "In the chamber, you have to stay ahead of hypoxia symptoms more than in an actual aircraft. It's important the participants learn how fast they can become hypoxic because otherwise they wouldn't realize how significant it can be and how fast it can happen."

Navy Senior Chief Petty Officer Mark Wyland, an explosive ordnance disposal technician, was taking the course again.

"Every five years or so, people will come back to take the course as a refresher," Lieutenant Price said. "Life and lifestyle changes can affect the hypoxia symptoms people will experience. The refresher course also allows them to put the dangers of hypoxia back to the forefront of their minds."

Petty Officer Wyland said he experienced numbness and his mental acuity degraded in the chamber.

"It comes on pretty quick," he said. "It's important to be able to identify those symptoms so you can take the appropriate actions to keep yourself and your co-workers safe."