AirWillie6475 From United States of America, joined Jan 2005, 2448 posts, RR: 1 Posted (8 years 4 months 3 weeks 6 days 21 hours ago) and read 2095 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?
VirginFlyer From New Zealand, joined Sep 2000, 4537 posts, RR: 48 Reply 1, posted (8 years 4 months 3 weeks 6 days 18 hours ago) and read 2026 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...)
"So powerful is the light of unity that it can illuminate the whole earth." - Bahá'u'lláh
Avioniker From United States of America, joined Dec 2001, 1109 posts, RR: 11 Reply 2, posted (8 years 4 months 3 weeks 6 days 17 hours ago) and read 1987 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
QantasA330 From Iraq, joined Dec 2000, 306 posts, RR: 0 Reply 9, posted (8 years 4 months 3 weeks 4 days 18 hours ago) and read 1472 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.
David L From United Kingdom, joined May 1999, 9294 posts, RR: 42 Reply 10, posted (8 years 4 months 3 weeks 4 days 18 hours ago) and read 1462 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.
David L From United Kingdom, joined May 1999, 9294 posts, RR: 42 Reply 12, posted (8 years 4 months 3 weeks 4 days 7 hours ago) and read 1386 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.