Return Flight Time Differences West To East

[Prudie]

Can anyone explain the reason why standard stated flight times are always much longer travelling East to West than the other leg. I understand about weather impact and route variations but in general the flight time is always much longer travelling East to West than it is the other way even though the flightpath is the same.

[bednobs]

also perhaps trade winds are slower?

[Prudie]

There are three prevailing wind belts in each hemisphere,
Tropical Easterlies: From 0-30 degrees latitude (Trade Winds).
Prevailing Westerlies: From 30-60 degrees latitude (Westerlies).
Polar Easterlies: From 60-90 degrees latitude.

I really am leaving it at that, I'll ask real people elsewhere who won't be so likely to be snitty (as usual)

[237SJ]

When you fly from for eg, Singapore to London you don`t go anywhere near the equator. You go north. When you fly from HKG to London you go across Siberia. And that is where the westerly winds are. Granted, the winds are more pronounced over the ocean which is why you can gain 1.5 hours on the way back from the Eastern Seaboard and only an hour from LHR to SIN but the winds do still come into play. If you fly up from South Africa you will find there is hardly much deviation in times at all.

[jno]

who's being snitty? 237SJ has given a full and informed answer.

[bednobs]

probably me, sorry i didnt mean to be - i literally have no understanding either of how winds work but honestly didnt understand how if a wind is coming from the west, it wont continue to go west round a circle.
PS, i am a real person

[jno]

it's also to do with routes, bednobs. the shortest distance between two points may be a straight line on a map but it can be very different on a globe.

[zebo]

Our flight from Singapore landed about an hour and a half early at Heathrow a few years ago. FLights back from the US are almost always much earlier that publicised, unless you have a tight connection at Amsterdam, then it's a run through the airport.

[jno]

zebo, they'll frequently exaggerate flight times, so people can't demand compensation for being late.

[douglas9401]

I blame Mercator for raising hopes and expectations.

[237SJ]

Flight times have always been scheduled longer than they take. Since long before compensation came into play. It`s to make up for last minute problems. Plus, the scheduled time is from push back, not take off so taxi time is factored in.

[KARL]

bednobs, the jetsream does not go directly east, not only does it weave quite a bit but in essence it travels in a spiral toward the pole, thus does not complete a circle.

[New Judge]

The idea that the rotation of the Earth is a significant factor is fanciful. By that notion, a helicopter could take off vertically from Hyde Park, hover at 500 feet for fifteen minutes, then descend and land in Bristol.

The determining factor in the difference in journey times is the prevailing wind. I've just returned from the western Caribbean. It took almost eleven hours flying time to get there (via southern Greenland, Newfoundland then down the East Coast of Canada and the USA, all to avoid a 200mph Jet Stream). It took just eight hours to get back when at times our speed over the ground (or rather over the Atlantic) exceeded 750mph - courtesy of the same Jet Stream.

[Zacs-Master]

But....if you look at a map of prevailing winds over the Pacific, they’re generally east to west BUT flight times from LA to Sydney (in theory with those prevailing winds) are an hour longer than the return journey.

[237SJ]

^ blimey, that was a long way around. What aircraft was it?

[New Judge]

Airbus A330-200. All the transatlantic flights that weekend (the weekend of Storm Ciera) took a similar routing. Newfoundland had recently seen over 100cm of snow and some of their airports were closed for four or five days.

[JimF]

The biggest effect in time difference is due to winds, whichever direction they happen to be blowing at the time, which is why sometimes flights between the same endpoints use different routes so as to avoid them. The atmosphere rotates along with the earth which is why e.g. the mushroom clouds from the two atomic bombs stayed above their targets. There are two effects which come into play here: Coriolis and centrifugal.

The Coriolis effect is most pronounced when flying from a pole to the equator. During that flight, the plane will need to build up the extra 1,000mph that the Earth is moving at the equator. Or, put another way, the plane propulsion will have to compensate for the Coriolis pseudo-forces.

The centrifugal force comes into play because the earth is curved, which means that the plane has to change its speed in a vertical way. However, at this point, the gravity is actually helping the plane because, due to the earth's rotation, the gravity is slightly less than it would be if earth didn't rotate. So the plane needs to produce less lift.

But there is absolutely no difference in flying West or East.