Jet pilots and O2

[DA Aquamaster]

How would you get toxicity problems at altitude (35,000+), even on pure O2?

Diluter demand systems use less than 100% O2 at lower altitudes and automatically adjust the percent based on altitude.

On many systems you can also over ride them and select 100% O2. 100% O2 can do wonders for your night vision.

 

[glbirch]

How would you get toxicity problems at altitude (35,000+), even on pure O2?

As DA Aquamaster said, it would be running on pure O2 at lower altitudes that could cause a problem.

 

[IslandHopper]

DA A .... above 25000 feet, IF one of the two pilots leaves the cockpit, then the remaining pilot must wear a mask while he's alone up there. (Above 41000 one pilot would have to wear it all the time, but that's a moot point since the aircraft isn't certified to fly above 41000 anyway.)

As for O2 toxicity ... even at sea-level, breathing pure O2 would only give you a ppO2 of 1.0 ... toxicity isn't really a problem till you reach 1.4-1.6 ppO2 (as in breathing pressurized air/O2 at depth.)

It could be just because I don't smoke and have good lungs (between running and diving, they get lots of exercise), but I've never noticed any night vision improvement from sucking on O2... and about 90% of my flying is done at night.

 

[glbirch]

As for O2 toxicity ... even at sea-level, breathing pure O2 would only give you a ppO2 of 1.0 ... toxicity isn't really a problem till you reach 1.4-1.6 ppO2 (as in breathing pressurized air/O2 at depth.)

Just guessing here, but as the system on a combat aircraft provides oxygen under postive pressure (IE at greater than 1 atmosphere) the pilot in theory could be breathing O2 at a ppO2 of greater than 1.0? Not sure how pressurized the system is, but I suppose I could wander over to a hanger and ask one of the techs who service the system if I really wanted to know.

 

[IslandHopper]

When delivered at positive pressure, it's done to prevent smoke/fumes from entering the mask/goggles (there are smoke-goggles integrated into the O2 mask). The pressure is not THAT positive, just enough to be greater than ambient.

Could be different on military fighter jets, i suppose, but I doubt it.