I heard that blood boils at 67,000' at ISA....can any of you astronauts confirm this...?

At or just above 55,000 ft your blood begins to boil so take care!

Pressure suit an absolute essential - otherwise prepare to scatter the ashes.

I suppose rather than a lung full of -40 degree air Id say your lungs would be exhaling the cabin pressure. I wonder if this rapid exhale is any good for the lungs.
while your are exhaling, one would be doning masks, switch mike audio to mask, activate the "rubber jungle" if it allready hasnt deployed simultaneoulsy emergency descent off the airway and advising ATC your actions, then a cabin announcement after that.All with that one exhaled breath! :):p
Nah only kidding. But the name of the game is to get DOWN ASAP and NOT deal with super chilled Oxygen difficient air.

My 2 cents worth.

Sheep.

P.S used to FLY unpressurised B90 King Airs on long hikes across the Gulf of Mexico and Carribean sea. Its lovely stuff Oxy,makes your mouth dry, and very hard to swallow cake and drink tea. But once you take of the mask off at say 22-26000 ft, the initial symtoms of hypoxia dont take long to develope, tunnel vision etc. From experience its pretty bad stuFF not recommended, only incontrolled decompression chamber conditions.

Emergency breathing techniques? Don't even think about it. As indicated on another currently running forum, it's the Oxygen partial pressure (or lack of it) that's the killer. With certain breathing techniques you may be able to increase the air pressure SLIGHTLY, but to nowhere near the degree necessary.

Holding your breath? At 40,000 feet depressurised, to maintain Sea Level pressure inside your lungs would be a 12.0 PSI pressure differential. That's enough to burst any aircraft pressure hull.

Oxygen is the ONLY answer, and at higher levels, at 100% and under pressure.

Regards,

Old Smokey

Just to confirm my colleague was wrong...:E

Is there a difference between climbing at very high altitudes in an unpressurized plane, breathing oxygen, and being at the same high altitude in a pressurized plane, experiencing a sudden decompression?
(like suddenly opening a bottle of coke).
That was his point...

Does the second case make the blood boil, at least for a few seconds?

Armstrong's Line
 

The phenomena of blood boiling at high altitude is a fact. It is due to gas (Boyle's) laws. At about 62,000 feet, air comes out of solution (blood). This altitude is also known as the Armstrong's Line. This is why pilots who fly the U-2 and SR-71 high altitude a/c has to wear a full pressure suit, to avoid this unpleasant event. Colonel Joseph Kittinger, the man who did the world's highest altitude parachute jump at 102,800 feet also had to wear a pressure suit when he leaped off from the balloon!

So that scene in the movie "2001 A Space Odyssey" where Dave has to spend some 20 seconds or so in the vacuum of space without a space suit helmet while getting back into the mother ship is BS? Even HAL didn't think he could do it!

http://www.palantir.net/2001/sounds.html
"You're going to find that rather difficult."

William H Rankin, famous as The Man Who Rode Thunder, ejected from a F8U at in excess of 47000ft and M=0.82 and took 40 mins to get to the ground.

He was wearing no protective gear at the time although he was on oxygen at the time of the ejection.

You can read the story in Wild Blue, Pg 38-61.

I have always thought that! It was one of the resons I have always marked the film down. It was so patently not possibly for a human being to be in a total vacuum for 20 seconds and live.

Unless I mis-remember, this mistake was also made in one of the Alien series.
--------------------
"I tell you, we are here on Earth to fart around, and don't let anybody tell you any different." Kurt Vonnegut, Jr.

It's appropriate that a discussion regarding the usefulness of "Emergency Breathing Techniques" at high altitude should have drifted into the realm of science fiction, because that's what it is - PURE FICTION.

To LEM's question - "Does the second case make the blood boil, at least for a few seconds?", the answer is YES. And the end result of a few seconds of blood boiling is about the same as the micro-second that it takes for a bullet to pass through your heart - You're Dead!

Emergency / Rapid breathing techniques at Medium altitude will lead to hyperventilation, unconsciousness, and death.

Regards,

Old Smokey

So now I'm really puzzled!...

Old Smokey, you mean a SUDDEN decompression at level 400 is fatal anyway?

It can't be! The whole aviation business would have to stop!

:confused: :confused: :confused:

Not even remotely LEM, the "blood boiling" syndrome does not occur until well above 40000 ft, various sources differ, but in the vicinity of 60000 to 82000 feet.

Regards,

Old Smokey