I was just wondering.  I know mostly unpressurized aircraft wouldnt fly above 10,000 ft, but what is about the maximum altitude that you can fly without needing supplimental oxygen?

With proper acclimatisation its possible to climb Everest without oxygen. However the symptoms of altitude sickness can begin round about 5000ft. The Deathzone begins at around 17,000ft at this point there isn't enough oxygen to sustain human life properly and the body begins to die slowly.

If you fly over 12,500 feet for more than 30 minutes you are requred to have suplimental oxygen as flight crew. 


Having undergone high altitude training recently, I lasted about 7 minutes at 25,000 before I had to use the mask. (one of the safety officers in the "chamber" actually had to tap me on the shoulder and help put it on.  Apperantly they were talking to me trying to get my attention for about 2  minutes)  Although, my time of useful conciousness was only about 4 at the most.  After the 4 minutes I had no idea what I was doing.

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I don't think this is correct. Someone can survive on top of Everest without an oxygene mask but not climb . In fact soemone can feel quite well while sitting but most probably would be unable even to stand up.

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This is very interesting. By that I mean the different Laws that countries have. I am presuming that you are American? I am in Canada ( for the time being.....we are moving to Wisconsin) and our CAR's say that we cannot fly over 10,000ft without supplemental O2. Being a Paramedic, I can tell you that the effects of Hypoxia vary with the tollerences and compositions of each individual. I think that these hights are just "guidlines" for the governments to be "safe" so to speak. I do know that while performing some joint training with another country while in our SSF our HALO jumps from as low as 15,000 ft needed O2 equiptment.

Very good points there Hagar. 16.5 !!! in a SPIT ......
......Ok...where do I stop drooling....... 8)

I'm sure you hit the nail with the fact that not much was known back then about Hypoxia. It just seems funny how low the regs are to be safe nowa days
Hmmm..........I wonder.....if possibly some of those "unkown" air loses from all sides was perhaps in some way affected by Hypoxia.

Now all we need is a time machine so we could fine out for ourselves...

16,000ft as this man found out:

(1982, California) Larry Walters of Los Angeles is one of the few to contend for the Darwin Awards and live to tell the tale. "I have fulfilled my 20-year dream," said Walters, a former truck driver for a company that makes TV commercials. "I'm staying on the ground. I've proved the thing works."

Larry's boyhood dream was to fly. But fates conspired to keep him from his dream. He joined the Air Force, but his poor eyesight disqualified him from the job of pilot. After he was discharged from the military, he sat in his backyard watching jets fly overhead.

He hatched his weather balloon scheme while sitting outside in his "extremely comfortable" Sears lawnchair. He purchased 45 weather balloons from an Army-Navy surplus store, tied them to his tethered lawnchair dubbed the Inspiration I, and filled the 4' diameter balloons with helium. Then he strapped himself into his lawnchair with some sandwiches, Miller Lite, and a pellet gun. He figured he would pop a few of the many balloons when it was time to descend.

Larry's plan was to sever the anchor and lazily float up to a height of about 30 feet above his back yard, where he would enjoy a few hours of flight before coming back down. But things didn't work out quite as Larry planned.

When his friends cut the cord anchoring the lawnchair to his Jeep, he did not float lazily up to 30 feet. Instead, he streaked into the LA sky as if shot from a cannon, pulled by the lift of 42 helium balloons holding 33 cubic feet of helium each. He didn't level off at 100 feet, nor did he level off at 1000 feet. After climbing and climbing, he leveled off at 16,000 feet.

At that height he felt he couldn't risk shooting any of the balloons, lest he unbalance the load and really find himself in trouble. So he stayed there, drifting cold and frightened with his beer and sandwiches, for more than 14 hours. He crossed the primary approach corridor of LAX, where Trans World Airlines and Delta Airlines pilots radioed in reports of the strange sight.

Eventually he gathered the nerve to shoot a few balloons, and slowly descended. The hanging tethers tangled and caught in a power line, blacking out a Long Beach neighborhood for 20 minutes. Larry climbed to safety, where he was arrested by waiting members of the LAPD. As he was led away in handcuffs, a reporter dispatched to cover the daring rescue asked him why he had done it. Larry replied nonchalantly, "A man can't just sit around."

The Federal Aviation Administration was not amused. Safety Inspector Neal Savoy said, "We know he broke some part of the Federal Aviation Act, and as soon as we decide which part it is, a charge will be filed."

cheers,
ashar 8)