A question for flying any fighter aircraft, not just the F-14.... How uncomfortable is it to wear, and breath through an oxygen mask? How much of your exhaled breath do you rebreath?
I've never had one on, but I have worn those clear, plastic medical oxygen masks that go over your nose and mouth. And they're horrible. You can watch the condensation build up on the inside of the mask, because you are inhaling part of the last breath you just exhaled.
Do aircraft oxygen face masks push more oxygen in order to help prevent this?
Navy regulations required that you wear the mask anytime you were on the flight deck, and from takeoff to landing, and I was always conscientious about that. Other folks were not, and suffered some severe consequences as a result.
There was a famous mishap in which crew took off their masks and helmets for a photo opportunity with another airplane, after the photo was taken, that crew dropped back a bit from the formation, and was never seen again, the aircraft hit the ground about 10 minutes later and they did not survive. Without a flight data recorder, the working theory was hypoxia.
A squadron mate, and frequent bozo in the airplane, was flying around one night without his mask on, and got the bends. Nitrogen narcosis, the result of the nitrogen in his blood boiling off at altitude, he was able to make an emergency landing, and got rushed to the pressure chamber at Norfolk Navy base where the N2 went back in solution. Don’t worry, he flies for UPS now.
I never found the masks objectionable. I have a rather long face, as measured from the bridge of my nose to the bottom of my chin, and so I had to get a rather unusual size mask, but once I got one that fit, the thing just worked great.
We each had our own masks. There is no sharing, or common use. So, I was careful to clean the thing, and keep it clean. I would’ve been a lot less inclined to use it, had it been something that I had to share with other people. Clamping something on your face for hours at a time when it’s a common use item, just seems a little, unsanitary.
Breathing is pretty easy with them on, there’s not a whole lot of your breath coming back in. But it’s not like breathing through a paper bag - what’s coming in is 100% pure oxygen in Navy aircraft (the Air Force uses diluted oxygen) So, even if there’s just a little bit of mixing with your exhaled breath, the fact that you’re breathing in 100% pure oxygen means it’s way easier to breathe, and you’re getting more oxygen than you do breathing pure air at sea level.
Your breath, the carbon dioxide, and the moisture in it, are completely exhaled. And what’s coming in is pure, dry, oxygen it’s nothing like the medical mask that you experienced, that’s clammy and has a little bit of oxygen coming in. What you’re breathing in with those is a mix of ambient air, exhale, air, and oxygen. What we got was pure O2 - dry, clean, odorless. In fact, I always carried a plastic canteen/water bottle, because that stuff would dry you out.
By the way, after a few minutes, on pure oxygen, most of the nitrogen in your blood comes out of solution. So, even if you take the airplane up to a very high altitude, you’re not susceptible to the bend, unless you’re a bozo, and were flying around with your mask off.
Once you start taking the airplane up to high altitude, the cabin altitude inside the cockpit gets pretty high as well. For example, when I once took the airplane up to 60,000 feet, the cabin altitude inside the airplane was over 27,000 feet at that altitude, the oxygen regulator is pushing, sea level pressure onto your face, and there is a substantial difference between sea level pressure inside the mask, and the cockpit pressure outside the mask, so the O2 is being forced into your lungs, and exhalation is actually something you have to, physically, consciously, do. Breathing out took some real effort.
Most of the time I wasn’t even aware that I was wearing the mask. It was just part of the kit from head to toe; I had on a helmet, oxygen mask, flight suit, torso harness that went from my legs up over my shoulders, and around my chest, survival vest attached to the torso harness, G-suit, boots, and gloves. The thing on my face was just another part of the whole experience. The connection of the oxygen mask into the seat itself, included the communications wiring. So, as you plugged into the airplane, you connected the microphone that was in the mask, and the speakers that were in your helmet. Because the mask and the helmet were separate pieces, there was a little connector plug between the mask and the speakers in the helmet.
The one time the oxygen mask became an issue was when I was at low altitude, in Puerto Rico, running in on a bombing target. We had been at 500 feet, 480 knots, running in at low altitude. As we “popped up“ for the weapon delivery, we peaked at about 4000 feet, rolled, inverted, and began pulling down to deliver the bombs to the bull’s-eye. While we were inverted, I took a quick glance to my left, to check my relative position against my wingman when I came back, that communication cord that connected my oxygen mask to the speakers in my helmet earcup became disconnected.
I wasn’t aware that it happened.
So, as we pointed at the ground at over 480 kn, well above an airspeed at which an ejection would be survivable, I could not hear the range officer clear us “Hot“ for weapon delivery. Our bombs were live, and this was a very important, safety consideration. I asked my RIO if we were cleared hot, but because my helmet speakers were disconnected, I couldn’t hear even myself, so I said it really loud.
Hearing nothing, I repeated, “ARE WE CLEARED HOT?” But all my RIO heard was my unintelligible yelling, because I was so loud.
As my RIO, “Vart” tells the story to this day, “Here we are, pointed at the ground, at 500 knots, too fast to survive an ejection, with seconds to impact, and Astro is yelling unintelligibly, and I am wondering what the **** is wrong, if I am about to die or, if this is all going to work out…”.
I did not drop the bombs (since I didn’t have clearance) at release altitude, I pulled up and off target, rejoined the flight, and realized what had happened. I plugged that little cord back in, and, much to Vart’s relief, was able to hear him, and the radios, again.
