Disparity in LGW-CUN flight duration

Old Apr 4, 11, 4:40 pm
  #1  
DS7
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Disparity in LGW-CUN flight duration

Now i know that prevailing winds etc mean that flight times US airspace bound are a little longer than UK bound but I've been meaning to post (and keep forgetting!), I did the LGW-CUN run a few months ago. 11hrs there but less than 8.5 on the way back; and that's runway to runway!

Forgive my ignorance but please educate me. Why such a big difference when somewhere like SFO is less than an hrs difference???

com

bracing myself for the plethors of "Simples" responses

Thanks
DS7
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Old Apr 4, 11, 5:25 pm
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I think this pretty much sums it up....

http://squall.sfsu.edu/gif/jetstream_init_00.gif

Basically you are almost always fighting a headwind on the way there, and it is almost always a tailwind on the way back.

LGW-CUN is about 5000 nautical miles...

So think, if you can average 500 knots for your trip, with no wind this would take 10 hours to cover 5000 nautical miles.

But on the way you have a headwind, say average 50 knots, so your average speed is now 450 knots hence 11h7mins, and on the way back this is a 50 knot tailwind so 550 knots hence 9hr5mins....

This explains a 2 hour difference so not difficult to work out where 2.5 hours difference comes from. There is usually no obvious (sensible) way to avoid these winds.

SFO/LAX/SEA/YVR are a bit different because the majority of the flight can be flown outside the jetstream, or a shorter distance (over greenland/northern canada) on the way out avoiding the jetstream, but on the way back taking advantage of the jetstream, but on a longer route (northern USA, normal north atlantic route), hence the time difference is not so large.
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Old Apr 5, 11, 1:17 am
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Originally Posted by limabean767 View Post
SFO/LAX/SEA/YVR are a bit different because the majority of the flight can be flown outside the jetstream, or a shorter distance (over greenland/northern canada) on the way out avoiding the jetstream, but on the way back taking advantage of the jetstream, but on a longer route (northern USA, normal north atlantic route), hence the time difference is not so large.
I don't know about CUN but certainly flights to MEX often still deviate way North to find the most efficient route ... I remember being on an LHR-MEX flight which went over Iceland, central Greenland, Hudson Bay and then pretty much due south over the US to MEX ... but then on the MEX-LHR the route back was much more straight line looking passing out over Florida and straight over the mid Atlantic to LHR.

All sorts of complex calculations I'm sure go into determining the optimum routes .. it often seems to me that I'd prefer the shorter flight to be the outbound day flight rather than the night flight home .. but I guess you can't argue with the winds !
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Old Apr 5, 11, 2:48 am
  #4  
DS7
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Very useful. Thanks very much folks.

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