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Thread: Does any other aircraft reach 40,000ft of calibrated altitude?
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Old Feb 23, 2020 | 10:47 pm
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s0ssos
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Originally Posted by Starship73
It's generally more efficient to fly higher if the weight of the aircraft allows (ie there is an acceptable margin between overspeeding and stalling). However it is my understanding that some flight crews dislike going much higher than that in the daytime due to the higher UV exposure. ATC constraints also come into play of course if the airspace is congested. The 747-400 and 777-300ER are certainly capable of cruising at 40,000ft and higher if operational conditions allow.
Interested with the presumption that you get more UV, I looked it up. And it seems there is not a conclusive answer.
One study says there is increased UV exposure: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4476387/
Another one says there is not: https://www.ncbi.nlm.nih.gov/pubmed/28923144
The first study, that says there is, was done in a plane that none of us fly. So maybe it isn't as valid as a commercial jet like a twin aisle Airbus or Boeing.
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