Five Minutes at 26,000-Feet Simulated… and I Forgot How to Count

By Addison DeWitt

Each year at EAA AirVenture, the FAA Aviation Safety Center opens up its doors and gives the public access to the Portable Reduced Oxygen Training Enclosure, or PROTE. This traveling altitude chamber lets pilots experience the effects of hypoxia in a controlled environment… and things can get interesting quickly.

After hearing about it for years, I finally decided to get in line and see what all the excitement was about. I had scoped out the sign-up situation earlier in the week, but realized I needed a better game plan after finding out that the 40 daily slots fill up in mere minutes. So, on a later day of the show, I made the early-morning dash and earned myself an 11:00 spot.

The PROTE simulates what it’s like to be at 25,000 feet without cabin pressurization or supplemental oxygen, dropping oxygen levels from the normal 21 percent to around 7.5–8 percent. That’s enough to cause confusion, memory loss, or unconsciousness in just a few minutes, and can be fatal in under 25. It’s designed to help pilots recognize their individual symptoms of hypoxia, which vary from person to person but stay for a lifetime, before they find themselves in a real high-altitude emergency.

When it was my group’s turn, we headed in, signed a waiver, and were handed a worksheet with a series of tasks: a word search, five math problems, and four flight planning questions that, under normal circumstances, would be simple.

Once inside the chamber, the questions stopped looking so easy. My first symptom hit fast: dizziness. By minute two, I had completely abandoned my word search after finding only the word ‘hypoxia’ (fittingly). I never so much as acknowledged the math questions.

Our supervisor, who was constantly monitoring and ready to step in if things got dicey, asked me around the three-minute mark to count backward from 100 by threes. I got to 64, or at least thought I did - I wrote “74” on the paper and still don’t remember doing so.

The chamber has a checklist section for symptoms you can fill out minute by minute - I ticked off dizziness, tingling, and fatigue, and by minute five, I was putting my mask back on. Some people only lasted 90 seconds, though a special few stayed off oxygen the entire time.

After exiting, I had a vague recollection of what just happened…and a much clearer view of how quickly hypoxia can sneak up. Sign-ups for PROTE are open each day of AirVenture and at many events year-round. It’s an eye-opening (and mildly disorienting) experience that I firmly believe every pilot should try, at least once.

FMI: www.faa.gov