In the December 2014 issue, I discussed a marathon flying day I had many years ago (“Advanced Pilot: Fit to Fly?”). I was in my late twenties then, and I quickly learned why spending half a day at altitudes from 8,000 to 11,000 feet really can take a toll on those of us who live at lower elevations.
In the late 1990s, as a reviewer of products for AOPA Pilot, I got a chance to play with a pulse oximeter and used it on several flights. The results were eye opening. I always attributed headaches following long flights to my David Clark headset—affectionately known otherwise as “David Clamps.” I should’ve given my old DCs some slack. After cruising home from Wichita at 11,500 feet, a check of the pulse oximeter showed my oxygen saturation level (SpO2) at about 88 percent and my pulse was pushing 100 beats per minute (bpm). At sea level, I registered 99 percent SpO2 and pulse of 60 bpm. No wonder I felt so beat after long flights!
I almost always climb high for long flights since that’s where light airplanes achieve their best true airspeed on minimal fuel. But what the pulse oximeter so vividly told me was that I was starving my brain of oxygen while my heart was working overtime to keep it satisfied. I descended to 9,500 feet where SpO2 was 92 percent but my heart was still beating fast.
I began to bring an oxygen bottle and learned the positive effects that using it had even at the so-called “breathable” altitudes, where the regulations don’t require supplemental oxygen. After strapping on the oxygen at 11,000 feet, SpO2 returned almost instantly to 98 percent and, over time, my heartbeat settled down to a much more reasonable 70 bpm. Most important, when I landed after a long flight at altitude, I didn’t feel like I’d been run over by a truck anymore.
Later, when I started flying long flights for a major airline, I noticed the importance of staying hydrated. At first, I noticed sinus problems because of the dry air at altitude. I also could drink a liter bottle of water on a four-hour flight and not have to visit the lavatory. After a little research, I found that the cockpit of an airliner has about 3 percent humidity, even less than the Sahara Desert. Airline cabins are dry, too, but better (10- to 20-percent humidity) since there are so many people breathing back there.
With desert-like conditions, I’ve learned to combat the effects by drinking plenty of water. Pilots are ripe to get kidney stones and word in the crew lounge is that passing one of these will be a lifelong reminder that staying hydrated is a good thing. I use a saline solution to keep my sinuses hydrated and apply lotion containing sunscreen to give my skin something to drink, while combating the UVB rays of a less-filtered sun up there.
I like to avoid alcohol within two nights prior to a trip. While alcohol is great for getting you to sleep, it also provides a lousy quality of sleep and wakes you up early. Thinking of knocking a few back on your next flight as a passenger? Given the 8,000-foot cabin altitude, the drying effects of alcohol, and the aforementioned humidity level, you can imagine the compound effect. In fact, many of the medical issues that occur in the cabin involve people fainting. Not surprisingly, most of them admit to not drinking water and/or consuming alcohol instead.
Many years ago, I took a flight physiology course at Andrews Air Force Base in Maryland. The climax of the program was a “ride” in the altitude chamber, where participants are taken off oxygen at a simulated 25,000 feet and are given tasks to do while noting how they feel. Being the youngest guy in the chamber, I figured I’d hang on longer than most and divided time between my tasks and checking out how the others were doing. I didn’t note any symptoms such as dizziness, fingernails turning blue, or inability to focus.
What I do know is that I woke up to the proctor in my face saying, “we almost lost you” and an oxygen mask force-feeding me a rush of air. What happened? Apparently I’m the worst type of person when it comes to hypoxia—I’m fine until the moment I’m not. Apparently, the proctor ordered me to put my mask on multiple times. He observed me twitching like a fish out of water. When it was clear I was out of it, he strapped the mask on for me. A few seconds later, I was back in reality with 15 other guys looking at me as the shining example of hypoxia. Crow eaten.
Because of this experience, I’m far more aware of the negative reactions I personally have with hypoxia. I highly recommend taking the time to attend one of these courses to learn your own symptoms and ability to recognize them. These days the free program is only available at the FAA’s Mike Monroney Aeronautical Center adjacent to the Will Rogers World Airport in Oklahoma City. For more information visit the website or call 405-954-4837.
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