In Response to Kevin Ware’s “A Medical Look at Hypoxia” (December)

You may recall that after your recent article on hypoxia in Twin & Turbine I contacted you for your recommendations on an appropriate cylinder for my JetProp. Subsequently, I ordered a 9-cubic foot M size cylinder, regulator and carrying case for $168 (a mustache cannula was already in my possession). The local FBO at VNY wanted $70 to fill it. Instead, I went to a medical gas supply house, and after showing my medical license, they filled it for $17.25.

Last night, I had the opportunity to try it out. I was flying an Angel Flight, and after deplaning my passenger in Redding, California, took off again for the 1:45 flight back to VNY. It was well after dark, with cloud tops around 20,000. After leveling at FL250, the pulse oximeter showed my SaO2 to be around 85 percent, with a cabin altitude of 9,500. I put on the cannula with a flow of 1 LPM. After checking a couple of minutes later, my saturation sat around 93 to 94 – a much better place for the oxyhemoglobin dissociation curve! Needless to say, it remained on until the cabin was below 5,000 on my descent. Based on your recommendation, this is my new SOP. Thanks again for your sage advice.

Dr. Stuart Bloom


Great article on hypoxia – thank you. It assisted me in having my commercial oral examiner’s eyes glaze over while I explained the workings of the SA node. 

See the lead article in IFR Refresher, Feb. 2019, vol 33, issue 2. They may have misdiagnosed what occurred to this 78-year-old pilot. Lastly, I bought an oximeter and portable oxygen tank to accompany me in my Cirrus SR22. Thanks again for your insights! 

Dr. Henry Koch, Ph.D. 


A recent reader email raised the question of the effect of cabin pressure on an auxiliary O2 bottle. I have one of these tanks, which is rated at 3,000 psi and can only be filled to that pressure with a booster. At sea level, the atmosphere is 14.7 psi, or about 0.5 percent of the tank rating. In a perfect vacuum, the tank differential would only increase by 0.5 percent, and the pressure relief valve on his type of tank is typically 5,000 psi. One would have to have a structurally defective tank and be very unlucky to have a problem with a cabin depressurization, but hey, nothing would surprise me when flying.

Mike V.


In Response to Scott Kraemer’s “Listen to Your Body” (January)

I would first like to thank you for sharing your personal experience. Second, as a physician, I see so many people who ignore the warning signs their bodies are telling them and live lifestyles that are not conducive to living long and healthy. 

In the pilot population, however, I think some people get a false sense of security because they have been issued a medical certificate. Your case shows how inadequate the FAA medical certification system is for promoting good health. All it does is certify an airman as being fit to fly for the duration of the certificate. It does not look deep enough into one’s fitness level to be able to predict how healthy and how long one may be expected to live. So, I hope more pilots will heed your advice and realize that they need to do more to take care of themselves more than just passing an FAA medical exam every few months or years.

JP Soldo, DO


In Response to Kevin Dingman’s “Debrief” (January)

In your January article, I picked up on a simple and obvious point but I hadn’t thought to do it myself earlier. Almost since I started flying, I’ve taken notes during the flight to help me improve (the debriefing). I normally write these in one of the following places: my nav log; the paper pad that I have on a kneeboard where I write clearances and weather; a separate pad of paper; or a Post-It. I even have some symbology that has evolved over the years to be able to quickly jot down such notes quickly. 

I’ve been very good about following up from my notes but then I just toss them away afterwards. Your point about transcribing them to a persistent journal makes total sense but I hadn’t considered it. I have some physical moleskin type journals I’ve been given that would be perfect. I make extensive use of notetaking and journaling software that would also be great. Hopefully, I’ll later be able to look back on years of lessons learned. Thanks a lot, and keep up the great writing.

Marc Dulude


In Response to David Miller’s “Flying with a Mentor” (January)

I enjoyed your article very much. It is interesting that you and I have many of the same experiences. I have been flying since the late 70s and I recall a similar time. I have always believed in two pilots for business, and have had a professional pilot on my payroll for most of that time – a total of four of them. For personal use, I almost always fly single pilot in case I need to sit on the ground for a day, I can adjust. Interesting in that your formula for a mentor I applied to my professional list, and I think I am two for four. If I had applied your reasoning, it might have been much better. Take care and fly safe.

Ron Fedrick

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