A4H Flight Member Dr. Erik Seedhouse recently completed High Altitude Indoctrination (HAI) training at Defence Research and Development Canada, Toronto, which has a hypobaric chamber capable of simulating conditions up to 100,000 feet altitude.
The HAI Erik completed included a rapid decompression to 10,000 feet while he was breathing a Combined Altitude Depleted Oxygen (CADO) mix of 10%, which allowed him to reach an equivalent altitude pressure of 25,000 feet. While at 25,000 feet Erik completed various mathematical tests to experience the effects of hypoxia. Then he connected his air mask back to the regular air supply and descended.
HAI is an important exercise because it prepares one for emergency situations when an air or space craft might lose cabin pressure, such as when the vehicle must be abandoned during flight. The resulting rapid and explosive decompression doesn't give passengers and crew much time to react. Thus, they must be able to recognize the signs of hypoxia.