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Flying At FL400+  
User currently offlineAirWillie6475 From United States of America, joined Jan 2005, 2448 posts, RR: 1
Posted (9 years 1 month 3 weeks 2 days 7 hours ago) and read 2320 times:

The WN and FL 73Gs, I noticed, cruise at 39-40k altitude range during long flights . There are advantages to cruising at that altitude if you can manage to get there but is it safe to stay up there? Isn't there an issue of atmoshperic radiation above 40k that could affect the passengers?

12 replies: All unread, jump to last
 
User currently offlineVirginFlyer From New Zealand, joined Sep 2000, 4537 posts, RR: 41
Reply 1, posted (9 years 1 month 3 weeks 2 days 4 hours ago) and read 2251 times:

I am not too sure what the exact radiation doses at altitude are. However, I did learn something interesting just yesterday - it is a requirement to carry a geiger counter if flying above FL490 (under Australian regulations anyway...)

V/F



"So powerful is the light of unity that it can illuminate the whole earth." - Bahá'u'lláh
User currently offlineAvioniker From United States of America, joined Dec 2001, 1109 posts, RR: 11
Reply 2, posted (9 years 1 month 3 weeks 2 days 3 hours ago) and read 2212 times:

737NG's have a top cruise altitude of 410 while classics are limited to 370-380.
Radiation at those levels isn't high enough (according to current "wisdom") to be a factor in those aircraft. With fuel being the highest cost item as of last Thursday I'm certain you'll be seeing the airlines operating as high as ATC will allow.



One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 3, posted (9 years 1 month 3 weeks 2 days 2 hours ago) and read 2203 times:

Whatever happened to concerns about cabin ozone concentration in long east-west flights in northerly latitudes, especially in the spring and fall?

That was the safety issue about twenty years ago.

Then there was the safety of the potable water put onboard airliners.

All I know is that jet airliners kill bees.

I find dead bees on the ramp all the time. Ever see dead bees lying around in your neighborhood? Something must be done!



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineB744F From Germany, joined Jan 2006, 0 posts, RR: 0
Reply 4, posted (9 years 1 month 3 weeks 1 day 20 hours ago) and read 2064 times:

Bees only live for a few weeks once they go out of the hive, so that explains why you see so many dead bees.

And according to a recent study, any radiation is harmful, no matter the amount. So who really knows?


User currently offlineContnlEliteCMH From United States of America, joined Mar 2005, 1458 posts, RR: 44
Reply 5, posted (9 years 1 month 3 weeks 1 day 17 hours ago) and read 2004 times:

Quoting B744F (Reply 4):
And according to a recent study, any radiation is harmful, no matter the amount. So who really knows?

Uh huh. So will any thinking person listen when a person flying at 41,000 feet complains about radiation, on a trip to lie on the beach for 20 cumulative hours?



Christianity. Islam. Hinduism. Anthropogenic Global Warming. All are matters of faith!
User currently offlinePilotpip From United States of America, joined Sep 2003, 3150 posts, RR: 11
Reply 6, posted (9 years 1 month 3 weeks 1 day 12 hours ago) and read 1949 times:

Quoting SlamClick (Reply 3):
Then there was the safety of the potable water put onboard airliners.

I won't drink it. Will you? I've heard about/seen the insides of those storage tanks and seen how the rampers care for that hose. I'll pass Big grin



DMI
User currently offlineMADtoCAE From , joined Dec 1969, posts, RR:
Reply 7, posted (9 years 1 month 3 weeks 1 day 6 hours ago) and read 1880 times:

Concorde cruised at FL600(I think).
Is radiation dangerous up there?


User currently offlineBongo From Colombia, joined Oct 2003, 1863 posts, RR: 5
Reply 8, posted (9 years 1 month 3 weeks 20 hours ago) and read 1813 times:

Quoting MADtoCAE (Reply 7):
Concorde cruised at FL600(I think).

Yes, you are right. And BTW at that altitude you can see the Earth's curvature...such a nice thing  Wink



MDE: First airport in the Americas visited by the A380!
User currently offlineQantasA330 From Iraq, joined Dec 2000, 306 posts, RR: 0
Reply 9, posted (9 years 1 month 3 weeks 4 hours ago) and read 1697 times:

The risk associated with high altitude radiation is far less apparent than the risk involved in the unlikely event of a depressurisation.

At FL400, a passenger has a Time of Useful Consciousness of only 30 seconds, a pilot at that altitude has only 20 seconds. At FL450 this reduces to 20 seconds and 15 seconds, respectively. Factor into this the notion that passengers will only be using a 'continuous flow' oxygen mask, which isn't at all efficient at that altitude. At that altitude, one must breathe PURE oxygen... not recycled air from the lungs.

Furthermore, above 40,000ft even breathing PURE oxygen does not provide that blood with sufficient oxygen, due to the lower partial pressure at that altitude. Special 'pressure demand' masks are required to deliver 100% oxygen at an increased pressure... and only the pilots will/should have these. This isn't even considering the fact that during an emergency oxygen intake can increase by a factor of twenty or so.

While radiation is certainly an issue for pilots at those altitudes over the course of a lifetime, the effects on passengers are negligable. That said, the most serious risk at these altitudes remains to be the rather improbable likelihood of a depressurisation.


User currently offlineDavid L From United Kingdom, joined May 1999, 9524 posts, RR: 42
Reply 10, posted (9 years 1 month 3 weeks 3 hours ago) and read 1687 times:

Quoting MADtoCAE (Reply 7):
Concorde cruised at FL600(I think).
Is radiation dangerous up there?

The radiation level was about double that of subsonic flights at FL350-ish but the flights took less than half the time so the net dosage was no worse. Crews carried some kind of dosimeter and, as far as I know, no-one ever received a dose that was considered to be worth worrying about.


User currently offlineVc10 From United Kingdom, joined Nov 2001, 1408 posts, RR: 16
Reply 11, posted (9 years 1 month 3 weeks 3 hours ago) and read 1681 times:

Concorde crews did not wear any radiation badge but the aircraft itself monitored both the instananeous and cumalative dose of radiation that it received.

little vc10


User currently offlineDavid L From United Kingdom, joined May 1999, 9524 posts, RR: 42
Reply 12, posted (9 years 1 month 2 weeks 6 days 17 hours ago) and read 1611 times:

I'd forgotten about the radiation meter but I'm sure I've read about individual meters. I'm not saying all crew wore them on all flights but I'm sure some were used, perhaps on earlier flights. However, until I can find positive proof, I'll have to concede that one.

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