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.

[Old_Geezer]

Prevailing wind ?

[emeritus]

The jet stream can be a factor

https://en.wikipedia.org/wiki/Jet_stream

[bookbinder]

The prevailing winds blow from west to east in the northern hemisphere, so they have the effect of slowing aircraft.

[Prudie]

I wondered that and that may be the reason crossing the Atlantic but this seems to be the case the world over and that's not got prevailing westerly wind.

[bhg481]

It's the earth's rotation. The earth is rotating under the aircraft so the destination is moving away from the departure point.

[brainiac]

To do with the jet stream. In a recent storm a 787 plane coming from the USA reached a record speed of 800 mph instead of the usual cruising speed of 560 mph, and arrived an hour early.
https://www.telegraph.co.uk/travel/news/virgin-atlantic-dreamliner-speed-record/

[sanmac]

Prudie, are maybe thinking about different time-zones...Just a thought?

[Prudie]

No - and I think the jet stream answer must be it. I recently travelled and as I hate flying these little things add to my anxiety :-) My trip is quoted as an hour longer coming back and it was even though the flight path was near identical. Also looked up a possible future long haul holiday destination with BA and it's 10hr 20 to get there and an hour longer to get back (both these journeys are travelling back East to West).

[237SJ]

Prevailing winds. Much more noticable in the winter as well (at least in the West)

[KARL]

bhg has it, if you fly "with" the rotation you are trying to reach a destination which to a degree is moving away. If flying against the rotation the destination is moving toward you. However, winds are of course very important and the flight plan (track and height) is adjusted accordingly.

[bhg481]

To amplify my earlier post; the circumference of the earth is roughly 24,000 miles and the earth rotates on its axis every 24 hours. This means a person standing on the equator is travelling at 1,000mph in an easterly direction.

[TheChair]

Here's a NASA Flight Controller explaining why the earth's rotation does affect latitudinal airplane travel, Karl & BHG

[TheChair]

Oops - forgot the link:
https://www.forbes.com/sites/quora/2017/03/31/why-the-earths-rotation-does-not-affect-latitudinal-airplane-travel/#246dcd9cddcd

[237SJ]

It's the winds.

[bednobs]

i cant read that article - can someone precis it? is it because all the air is moving too?

[THECORBYLOON]

The earth is spinning at about 500 yards a second at the equator. If I jumped from some point on that line and were in the air for half a second, would I land 250 yards away?

[Prudie]

Well that would at first seem to make sense but in fact it doesn't. The earth spins anti-clockwise which means the west gets closer to you - which would mean East to West flights (ie travelling West) would get you to your destination more quickly when in fact it's quite the opposite???

[bhg481]

TCL - No, because you would have the same east to west velocity as the earth when you jumped up, so you would travel with it.

[bhg481]

Prevailing winds blow from the west because of the rotation of the earth; without the earth's rotation they would blow north-south or south-north, depending on the latitude.

[237SJ]

We took 11:25 to get to Mexico recently. Blimey, we could have to got to Hong Kong in that time. Took 8:30 to get back (Storm Ciara) Going against the winds on the way out, riding the winds on the way back.