10,000 feet. Night vision is now degraded by 15-25 percent. The blood saturation has dropped to 90 percent and your brain is receiving the absolute minimum supply of oxygen. This is the absolute highest altitude at which you should have any trust at all in your own performance although your judgment is already severely compromised. Euphoria will prevent true self-assessment of your abilities. Physical hypoxic symptoms such as tingling and headache may not become apparent for four hours or more at this altitude, although judgment has long gone by the wayside. Above 10,000 feet blood oxygen saturation and performance degrade steeply.
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I've just started reading a bit and was startled to read references to flying over 10,000 feet without mention of oxygen. I understand that WW1 aviation was really early aviation, but did flyers routinely fly at levels guaranteed to produce hypocia?

Does WOFF in any way degrade performance at altitudes where the pilot would have been a semi-functional zombie?

I think hypoxia is the right spelling...

No WOFF simulates nothing in this regard that I have ever heard.
And yes, plenty of historical accounts of (and by) pilots mention oxygen deprivation or "Hypoxia."

Afaik, the new Realair Legacy v2 is the only flight sim aircraft that simulates hypoXia, was just checking. By WW2 if was known well enough that pilots would have had access to oxygen, I think. But in WW1, when parachutes were verboten, I assume that were hpoXia known the brass hats would have denied it is frivolous. No idea how difficult it would be to implement, just seemed WOFF would be a perfect place to showcase the problem.

IIRC DCS does at least something in that regard.
Oh and Falcon 3.0 :P
But now I'm getting cheesy!

It looks like you're quoting a source, Akmatov.

Personal experience as a military (HALO) parachutist and skydiver:
First of all, the science as I remember it from Altitude Chamber training 40 years ago. The greatest change in density occurs in about the first 5,000 feet above sea level (or mean sea level, MSL, which will be the point of reference for all future altitudes, as air density depends on distance from the Earth's core, not Above Ground Level, AGL). By the time you reach about 17,000 or 18,000 feet you'll be dealing with a density of about 50% that of sea level.

The military requires that all passengers (including crew) must have access to supplemental oxygen on extended (can't quote a definition of "extended", but I'd guess it's safe to assume more than 30 minutes, could be as little as 15) flights above 10,000 feet in an unpressurized aircraft. That's got a safety factor built in. The average person in good medical condition can retain consciousness indefinitely as high as 25,000 feet, although he/she will experience some of the symptoms you described. To what degree depends greatly on the individual, which is why every person in the chamber has to remove his/her mask at that "altitude" until he becomes familiar with what it feels like. For HALO jumpers, we'd use a pass-around bottle unless we were going above 15,000. At that point we'd hook up to a common source with multiple ports until time to stand up, when we'd switch to a bailout bottle carried in our packs.

I mentioned that they would have us take our masks off in the altitude chamber so we could get familiar with our symptoms. Another reason is so we could see just how insidious hypoxia is. It creeps up on you without your realizing it. The closest thing I could liken it to would be someone s-l-o-w-l-y turning up the volume on a stereo or tv, increasing only one degree every few minutes. You wouldn't notice until it was unbearable or turned back down suddenly. That's what happened to me on my first actual experience. We were only jumping at 12,000, an altitude I'd done many skydives at previously. The difference was that we cruised around for a while at that altitude. The instructor with the walk-around bottle told me to take a hit and I said I was ok. He insisted (when a Black Hat insists, you do it), so I took two breaths just to make him go away. I swear, it was like someone turned the lights on. And bear in mind, I'd already been to the chamber many times.

As to WWI; hypoxia was known to balloonists for decades before the Wright brothers ever got off the ground. But oxygen equipment is heavy and bulky, as were parachutes in those days. You're talking about aircraft that were pretty much maxed out carrying the pilot, machine guns, ammunition, and fuel. Some bombers had it. I've seen a photograph of a Gotha nose gunner kitted out for high altitude and he was sucking on an oxygen tube. But scouts? Where would you put it, and what would you do without to carry it? Ammo? Fuel? I'd guess that was the most likely reason.

Here's a photo of a scout with oxygen. This is Wilhelm Hippert of Jasta 74, complete with parachute, demonstrating the use of oxygen with his Fokker D.VII F 505/18. But this definitely was not common, as vB indicated.

Seen this pic many times, still doesn´t cease to amaze me.

Got to love the nose clamp.

That's a new one on me. Thanx, Jim...very cool.

Any info on how the system worked?

Very interesting post, vonBaur, and thanks for your service (though some of that sounds like real fun!)

Yessir, when vonBaur says he'll drop in to see you, he really means he'll DROP IN!!!

(I'll get my coat...)

von Baur, well said!

Like you I have trusted myself to all going well with the HALO experiemce. I go back to the very early days ( the late 1950's) when any thing below 15,000 was with out any Oxygen bottle. I am up for a HALO jump soon with the folks
down in Yuma AZ this spring. My wife is not happy, but she is happy it will be a "tandum jump". My log book has to many whiskers on it to be current and thus "safe".

Now near 79 ( this April ) I hike and hunt the high country in Colorado up to 14,000 feet with my son and grandson.
We check our oxygen level and heartbeat rate a few times during the climb to make sure the "old gezzer" ( me ) is doing OK. I have kept very active my whole life and still show very high Oxygen levels and low heartbeat rates at
high altitude. The WW1 pilots who were in poor shape or hung over would have had a hard time, and been a "target"
more than a hunter.