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Flat Earth Investigations / Re: What is the true map of the earth?
« Last post by Tom Bishop on Today at 02:58:06 AM »You're talking about the jetstreams as being a constant phenomenon.
Correct. The jetstreams are present year-round.
https://www.popularmechanics.com/science/environment/a9181/how-the-dual-jet-stream-sparks-this-weird-summer-weather-15634917/
"The jet stream is a year-round feature of our atmosphere, but the double jet stream phenomenon is more common in winter."
https://www.rmets.org/metmatters/jet-stream-weakening
"In the UK, we feel the influence of the polar jet stream (which is also sometimes called the ‘mid-latitude’ or the ‘eddy-driven’ jet stream), which forms due to the difference in the temperatures between the pole and equator. On its northern side lies colder air, and on its southern side warmer air – so its position is important for what type of weather we experience in the UK. It waxes and wanes with the seasons, being strongest in winter, but is a year-round phenomenon."
https://en.wikipedia.org/wiki/Jet_stream
"The northern hemisphere polar jet flows over the middle to northern latitudes of North America, Europe, and Asia and their intervening oceans, while the southern hemisphere polar jet mostly circles Antarctica, both all year round."
They aren't, they are variable, in location, direction and velocity. Like I said, its just a wind. If its above 60 kts, as you say, they term it a jetstream, but its still just a wind.
And you are absolutely correct that favourable jetstreams (like other winds) are exploited for the purpose of speed and economy, but if the jetstream is absent, or unfavourable, the flights still occur.
They don't. Flights are canceled all the time, especially long haul flights. See this quote by travel writer Maggie Teneva:
“Long-haul flights are often associated with long layovers and delays or cancellations.”
If there are unexpected changes to the jet stream or winds mid-flight, a non-stop flight might even stop for fuel:
“ Dozens of Continental Airlines flights to the East Coast from Europe have been forced to make unexpected stops in Canada and elsewhere to take on fuel after running into unusually strong headwinds over the Atlantic Ocean.
The stops, which have caused delays and inconvenience for thousands of passengers in recent weeks, are partly the result of a decision by United Continental Holdings Inc., the world's largest airline, to use smaller jets on a growing number of long, trans-Atlantic routes. ”
Per ETOPS, plane flight routes are required to be in vicinity of airports or landing strips for unexpected stops like that. Even long haul flights over oceans need the capability to make detour routes to islands with landing strips in case something like the above happens.
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Just look at the post-Covid-resurrected Qantas/LAN services between Chile and Australasia; they take place on schedule every time, eastbound and westbound. They can't be that anomalous can they?
Now try Googling Air France flight AF174 on 8 May. (Or here's a link);
https://www.flightradar24.com/data/flights/af174?utm_campaign=website&utm_medium=email&utm_source=sendgrid.com#351eba3d
Airbus A350 F-HUVC departed Paris CDG as AF174 for Mexico City but developed a problem over Newfoundland and returned to CDG. Flight tracking data shows that the return leg was performed almost completely along the same route and at a similar altitude as the outbound leg. Pretty dumb with a 300mph wind wasn't it, or maybe the airline actually knew the windspeed?
The Jet Stream can change in nature within hours. This is why those non-stop flights stopped for fuel in the previous quote I gave. Those planes didn't take off knowing that the winds would be unfavorable. Planes have a network which tracks the Jet Stream to follow the best path in real time. If that was the path it took, then it is simply because the flight logistics people determined that it was the best path at that specific time.
https://en.wikipedia.org/wiki/Jet_stream
"Jet streams may start, stop, split into two or more parts, combine into one stream, or flow in various directions including opposite to the direction of the remainder of the jet."
In this case, the jet stream probably just moved out of the way and the plane had enough fuel in its wings to take a long trip back, or there was a favorable path at a lower altitude.
Most typically, the planes take different routes on the return trip:
https://aviation.stackexchange.com/questions/29729/why-are-westbound-transatlantic-routes-located-hundreds-of-km-away-from-eastboun
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Why are westbound transatlantic routes located hundreds of km away from eastbound routes?
Looking at flights between NY and London (click to see route):
BA 185 (EGLL - KEWR)
United 941 (EGLL - KEWR)
United 16 (KEWR - EGLL)
The FlightAware anticipated routes are quite similar in both directions, but the actual routes for past flights are really remote from each other:
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?
