Oxygen, it can come in right handy when you’re trying to make your brain work well enough to do complicated things. Like fly an airplane. Problem is, airplanes perform best when they are up at altitude where oxygen can be in short supply. What to do?
Well, you can either make it by pressurizing the cockpit with compressed air from the engines, like in a jet, or bring it with you. Now flying in pressurized aircraft is a breeze, (see what I did there?) All you have to do is set the field elevation of your destination in the little window and forget it. Easy peasy.
Now if you’re not lucky enough to be flying a pressurized aircraft but still want to enjoy the magic of flight above 12,500 feet you’re gonna need to bring you oxygen with you in a more primitive manner. Like in a bucket. Which is essentially what a portable oxygen tank is.
You can get the O2 from a portable bottle one of two ways. You can use a cannula, which is basically a tube that runs under your nose with two small prongs that stick up into your nostrils or a full blown oxygen mask. The cannula work on most pilots up to around 18,000 feet or so. After that a lot of pilots need to switch the mask type in order to get enough O2 into their system.
I use the term “most pilots” because every pilot develops signs of hypoxia (lack of oxygen) at different altitudes for different reasons. If you’re old, out of shape, a heavy smoker, and heavy drinker, (cargo pilot) you might require O2 at a lower level than say, a young, marathon runner who reads to the blind in his spare time. (present day US Air Force pilot, with a pretty scarf and pressed flight suit)
Another big factor is acclimation. How much time do you spend at altitude not on oxygen? Remember many men have climber Mt. Everest without oxygen because they spend a month getting their bodies used to working in a high altitude environment.
Which is how come I have a particularly good tolerance for flight at high altitude. I work “up there” almost every day as a pilot and more importantly as a professional skydiver. Every summer I spend 6 days a week riding in a plane up to 14,000 feet, strapping some big 250 guy to my chest, stand up, walk down the aisle of the plane and jump out. All without oxygen. And that’s getting into freefall. That part can be quite demanding, believe me. Do that 15 times a day, every day all summer long and your high altitude tolerance will go up too.
What difference does it make you ask dear reader? “Aren’t pilots supposed to be on oxygen any time their above 12,500 for more than 30 minutes?” You might ask? Well, technically, yes. But it’s one thing to be pleasure flying in the good old USA, where you can get your portable O2 tank filled up at almost any airport you stop at. It quite to ferry a plane across the planet on a tight time schedule where oxygen refills can be hard if not impossible to find.
And because someday you might really need an hour or so of oxygen to, say, clear a really nasty thunderstorm or an area of unforecasted icing, you’d be wise to save a little O2 “just in case”
So why not just fly under 12,500′ when not in fear for your life? Lot’s of reasons. Especially when flying over the ocean in small single engined aircraft. You see when you’re ferrying a single, or any small aircraft for that matter, you’ll want to be as high as possible for a number of reasons.
Number 1. Better performance. Unless the high altitude winds are in your face you’ll get better range out of your plane if you’re up high, say 14,000-18,000 feet, because when flying across the ocean you never know when you’ll need that extra hour of endurance.
Number 2. Better radio reception. Back in the old pre GPS days (yes, I’m that old, I made 7 or 8 solo Atlantic crossings using nothing but a compass. Just like Lindberg.) the higher you were the farther out you could pick up the radio NDB beacon in the Azores. And that was the big thing back before GPS. Because once you were out over open ocean you really had no way of knowing what your position was. Oh, you got a winds aloft report before you left but if it was wrong you could be blown miles off course, and when you’re trying to find a small island in the middle of the ocean the farther out you pick up the beacon the better.
Number 3. More time to fix a problem and call for help. If you’re cruising along and your engine quits, you’ve got a lot longer to get out a position report and get ready to ditch if you start at 18,000 feet than if you start out at 8,000′.
So what’s does a real life ferry pilot to do when he wants to fly at high altitudes over the ocean but only has a limited supply of oxygen? Well I can’t speak from personal experience due to the whole self incriminating thing but I do know this one ferry pilot really well and here’s what he told he does. It turns out that this pilot has a really good tolerance for flying at high altitudes without supplemental Oxygen. He told me the trick to keeping his wits about him is to be really still in the cockpit. No excess movement. And if I, I mean he, get a little light headed or winded just a few hits on the old Oxygen bottle and he feels right as rain. In fact he’s done practical experiments using a sensor on his finger that measures the O2 level in his blood. It is truly remarkable how a few breaths of oxygen will bring the levels from the low 70s back up to levels.
And according to this unnamed ferry pilot this method can make a portable oxygen bottle go a long way. Apparently, I’ve been told, and you can’t prove anything.