Hypoxic but saved

November 4, 2009 by Bruce Landsberg

hypoxiaLack of oxygen causes brain fade or incapacitation. It happened again last week when the pilot of a Cessna 400 mentally dropped out but fortunately his daughter, who was not a pilot, was able to talk to ATC. The Corvallis was cruising at FL230 and had been cleared to descend but the pilot didn’t respond.

ATC and the daughter were able to work out a descent plan and finally got the aircraft down to a more oxygenated atmosphere. Even then, it a took awhile before the pilot was really with it and able to land uneventfully.

This is the second time this year that ATC have been “hypoxic heroes.” A Lear 35 crew also dropped out of reality and were barely functional. Controllers talked them down safely and all ended well.

A few thoughts: First, FAA should reward controllers for getting pilot certificates as they become far more capable of assisting in an emergency and are much better able to understand what they’re controlling – we could have a long discussion on that point.

Secondly, these incidents should be looked at closely for the potentially deadly consequences that would likely ensure without outside intervention. Did the C400 pilot run out of O2? Was he using a cannula above FL180 where a mask really is required. What is the monitoring system to let the pilot know immediately that he or she is about to become a vegetable?

As an aside, ASF offers both an online Pinch-Hitter course and a wonderful DVD that make great stocking stuffers for your cockpit companion.

As we ply high altitudes in light aircraft, it’s essential that both pilot and equipment are up to the challenge. High altitude training is essential even if you don’t fly a pressurized aircraft above the mandatory FL250. In my view, if you’re flying anything that is consistently above 14,000 get some solid training.

Bruce Landsberg
Senior Safety Advisor, Air Safety Institute

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4 Responses to “Hypoxic but saved”

  1. Cary Alburn Says:

    Forty plus years ago I had the opportunity as an AFROTC cadet to go through the high altitude training at Buckley AFB, CO. Although I was a resident of Laramie, WY (elev. 7377) and supposedly accustomed to higher elevations, my abilities at higher altitudes simulated in the altitude chamber were little better than the other guys, many of whom came from much lower elevations. At 18,000′ simulated, I was pretty useless.

    As I’ve gotten older, I have realized that my physical ability to process oxygen has deteriorated to some extent. While I once regularly flew without supplemental oxygen at the 11 and 12,000′ level, I now check my pulse ox with my pulse oximeter any time I’m flying above 8500′, and often I need supplemental oxygen just to bring my O2 percentage to 90% at elevations as low as 9000′. Lower oxygen levels compromise mental acuity and significantly affect night vision. I understand that anything less than 90% is likely to cause mental “fuzziness”, and I can attest that it is true.

    Part of the issue is that the FAA rule mandating O2 for pilots (12,500′ or higher for more than 30 minutes, or 15,000′ or higher) is unrealistic and fails to take into account density altitude. Just like an airplane’s engine is affected by density altitude, so is the pilot’s “engine.” There are many other reasons why an individual pilot might require supplemental oxygen at lower altitudes: if a smoker; if even slightly ill with a disease that compromises lung function; if slightly anemic; or just being older.

    Any of us is subject to needing supplemental O2, even at relatively low altitudes. Being aware of the possibility is the first step. Knowing when to use supplemental oxygen is the second step, and only a pulse oximeter can determine necessity. Purchasing and using supplemental oxygen when needed is the third. For less than a thousand dollars, a good supplemental oxygen setup and a quality pulse oximeter can be purchased, and it’s money well spent.

    Cary

  2. Rich Romaine Says:

    When I look at the typical O2 system for non-pressurized aircraft I wonder how many failure modes there are in the vinyl tubing, connectors and valves for what is a single string system to keep the pilot alive/functional. As a former tactical aviator (lots of O2 and pressure chamber time), current pilot and systems engineer (in my day job) it surprises me that there isn’t at least a failure warning requirement…hypoxia can be very subtle in a gradual failure.

  3. Peter Row Says:

    I agree wholeheartedly with Mr. Alburn.

    A simple pulse oximeter can be purchased for $50 to $75. One of the key benefits to the pulse oximeter is that it measures the ultimate parameter: oxygen in your blood. Thus, it detects failures in your mechanical oxygen delivery system, as well as failures in your biological oxygen delivery system. Generally, the only thing that will “fake-out” the pulse oximeter is carbon monoxide. Ideally, your pulse oximeter would also have an audible alarm, so that you don’t have to be looking at it (or more importantly interpreting its numbers) when you are hypoxic.

    You should make a personal commitment that you are descending if the alarm goes off, even if you have to declare an emergency with ATC to get the descent clearance.

    Peter L. Row, MD, EMT-P, FACEP
    Commercial, Multi, Instrument pilot

  4. Margaret Medford RRT, CPFT Says:

    Just wanted to point out that the mask pictured is attached to a small volume nebulizer used to give bronchodilator and other respiratory medication treatments. This would not be used to deliver O2 in an airplane as it has many small, unnecessary pieces that could be easily disconnected and lost. I would think that a simple mask running on at least 6 lpm O2 flow or a nasal cannula with 6 or less lpm O2 flow would be used.

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