While playing a flight sim, I noticed West winds were very strong at levels >FL350 and weaker around FL270 above the US.
I took a look at Flight Radar 24 to see at which level actual airliners were flying, and I was surprised to see they're mostly over FL350, despite the lower ground speed and increased fuel burn I assume should occur

Is there any reason for that ?

FL270 : Winds at FL270 FL390 : Winds at FL390


marked as duplicate by Dave, fooot, Community Feb 28 '17 at 16:13

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  • $\begingroup$ Related, if not answering the question: aviation.stackexchange.com/questions/12541/… $\endgroup$ – ROIMaison Feb 28 '17 at 14:28
  • $\begingroup$ these answers are really interesting but they don't mention winds $\endgroup$ – Nicolas Feb 28 '17 at 14:41
  • $\begingroup$ I think there is enough difference to not be a dupe if the focus is on why they don't fly at this height for these conditions rather than why they're generally designed to fly at a given height. The answer being that they're designed to fly at FL350 and the detrimental effect of flying in off-design conditions is bigger than the gain from favourable winds. $\endgroup$ – Notts90 Feb 28 '17 at 14:55
  • $\begingroup$ @fooot that's much more like it! $\endgroup$ – Notts90 Feb 28 '17 at 15:33
  • $\begingroup$ indeed ! thank you @fooot ! $\endgroup$ – Nicolas Feb 28 '17 at 16:12