Unicom: 01/05


Hum Along With Us
With reference to Dr. Brent Blues article Mid-teens Physiology (November 2004), I may have discovered a way to stretch the bodys ability to process and retain oxygen just a bit more effectively while flying at altitude.

I routinely fly our Cessna T210 at FL190-230 on long trips from St. Paul, Minn., to Providence, R.I. The typical 50+ knot tailwinds let us accomplish this nonstop. Its not uncommon for me to have five of the six seats filled, and of course, we have oxygen strapped on from 14,000 all the way up. With five pairs of lungs sucking my precious O2, however, somewhere over western New York, the gauge is starting to get a bit low. So, not exactly according to the book, we shut off one of the masks and simply pass a mask back and forth between two people in five-minute intervals. Get this, if the folks who are waiting for the mask simply hum softly, there is an unmistakable improvement in the retention of oxygen in their system. I cant be certain, but I believe what happens is a slight pressurization of the lungs, which in turn, improves the absorption of oxygen in the bloodstream.

I discovered this on earlier trips while descending to safe and legal altitudes (when we were down to our last few gasps of our onboard oxygen). While chatting away with the folks at Center, I notice that every time I talked to them, things would brighten up and definitely seemed clearer. So we experimented with a few different ways to simulate what had happened. Talking non-stop isnt much fun, but humming softly works just fine.

Certainly, this is no substitute for proper oxygen supplementation, but if you ever find yourself in need, for whatever reason, this method may provide you with a slight edge in your ability to better process and retain oxygen in your system.

Id be interested in Dr. Blues comments or anyone else that may have noticed this phenomenon.

Chad Crow
Via e-mail

Dr. Blue responds, Humming could increase oxygenation, but I doubt it.When creating a positive end pressure (e.g., pursing the lips and breathing out against resistance), there is an increase in perfusion. This is what chronic lung patients learn to do as well as what happens in a positive-pressure oxygen system used for high-altitude military and NASA flights. However, humming creates so little pressure that I doubt it would have significant impact.

Talking, on the other hand (and maybe humming as a reminder), increases ventilation of the lungs by increasing the depth of each breath which will increase oxygenation. I do not think passing a mask back and forth is a reasonable alternative, if only on hygienic grounds.

Using a larger tank, an oxygen-conserving nasal cannula or a mechanical/electronic conserver would be a better option. Since euphoria and reduced cognition is part of hypoxic spectrum, a pulse oximeter would be a better way to evaluate humming.


Simple Redundancy
Your November 2004 article, Redundant Singles, overlooked a cheap and fast way to get redundancy-add a Garmin 296 to your yoke. For $1600 you get a complete electronic instrument panel plus terrain avoidance, instrument approaches, color moving map, nearest airport data, etc, etc. And if your entire electrical system fails, it has a three-hour internal battery that is always charged.

Karl Malden said it best: Dont leave home without it!

-Lauren Ward
Via e-mail

Thanks, Lauren; youare absolutely right and were smacking our foreheads over the omission. In addition to the features you list, the 296 also has a pretty slick terrain avoidance feature. See the article beginning on page 4 for a discussion of terrain avoidance technology and how to use it.


Risk Management Survey
I just took your risk-management survey on the Web and I have a few comments. First, thanks for putting this together. The various scenarios you posed along with the decisions to be made about each of them are all very instructive and informative. I printed out a list of all 30 questions to demonstrate to my girlfriend the kinds of things I get stressed about when we fly. It was educational for her and, as a result, I think she better understands the kinds of decisions I have to make.

Second, many of your questions and the scenarios posed in them are unrelated to my normal flying. I am not an aircraft owner and rarely venture beyond the local area where I fly for practice and the occasional $100 hamburger or local fly-in. As my career progresses and I have greater financial stability, I hope to buy a airplane and use it for travel, but Im not there yet. So, many of the questions were simply over my head and a few of them I didnt fully understand. I hope I didnt skew the results youre looking for.

By the way, what results are you looking for?

Jim Scott
Via e-mail

Thanks for taking the survey, Jim and for your comments. The Aviation Safety Risk Management Survey (available on our Web site) is not really designed to generate any specific results for the magazine. We are extremely interested in the final results, of course, which will not only tell us a great deal about our readers but, hopefully, will help us design more useful articles and features for the coming months. Instead, its designed to get pilots to think about the various factors that can impact the safe completion of their next flight, whether it means landing in a stiff crosswind or cruising for several hundred miles under a low overcast.

As general aviation becomes more technology-driven, some pilots, especially those new to flying their own plane for personal transportation, dont fully recognize some of the risks. Their electronic devices tell them where they are as they sit back and let the autopilot fly the plane around the bad stuff. Thats fine, but theres more to it than that. As you start to fly more and make more decisions about when and where to go, we hope our little survey will help you make those decisions easier. Thats all there is to it.


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