Por que as rotas transatlânticas para oeste estão localizadas a centenas de quilômetros das rotas para leste?

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Are jet streams a net benefit in time and fuel savings? provides (basic) explanations about jet streams in the Pacific. However I'm looking for an answer focused on North Atlantic area, explaining the track system and the tracks location. In addition BA 185 route seems to be composed of two arcs, did they change their mind in flight because of the wind? or is this related to ETOPS or alternate airport at Santa Maria?

Looking at flights between NY and London (click to see route):

The FlightAware anticipated routes are quite similar in both directions, but the actual routes for past flights are really remote from each other:

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The two westbound routes are either 800 km north or 1,000 km south of the eastbound route (the dotted line shows the shortest path).

  • Why are the two westbound routes different and so remote from each other? Why this difference of about 1,800 km?

  • Why BA 185 route seems to be composed of two arcs?
    Did the pilots changed their mind in flight because of the jet streams? Is it related to ETOPS constraints, or alternate airport at Santa Maria? or something else?

por minutos 01.07.2016 / 11:05

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The reason this is done is due to the winds aloft. The Jet Stream is a powerful current of air that blows in a west to east direction. Airplanes crossing the Atlantic from west to east take advantage of the jet stream to get there faster and save fuel, so a course is chosen to stay in the stream as much as possible. Airplanes going from east to west will be slowed by the jet stream, using more fuel and taking longer to get across, so a course is chosen to avoid the strongest winds.

The difference can be very significant, I've been on flights from NYC to London which take 6h 30m, and ones from London to NYC that take almost 9 hours.

01.07.2016 / 11:36

Wikipedia article about North Atlantic Tracks says it is to avoid jet stream winds (when flying west) or use it (when flying east):

They are aligned in such a way as to minimize any head winds and maximize tail winds impact on the aircraft. This results in much more efficiency by reducing fuel burn and flight time. To make such efficiencies possible, the routes are created twice daily to take account of the shifting of the winds aloft and the principal traffic flow

Article links to daily map of tracks, complete with the position of the jet stream.

Jet stream winds have average speed 100 mph (160 km/h) so they are significant.

01.07.2016 / 17:22

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