skopsko From United States of America, joined Feb 2013, 28 posts, RR: 0 Posted (3 years 4 days 11 hours ago) and read 3221 times:
I flew IST-IAD yesterday and was surprised by the flight path as it seems like it added 2 hours to the flight. In Europe, instead of heading toward Germany/France and below UK, the plane flew north toward Sweden and above UK. What's the reason for this? From IAD to IST, the flight path was much more reasonable (going through Germany) and hence the flight was 2-3 hours shorter.
planeguy727 From United States of America, joined Mar 2007, 1306 posts, RR: 1
Reply 1, posted (3 years 4 days 11 hours ago) and read 3161 times:
Flights often take more northerly or southerly routes based on the winds. While the direct line approach makes basic sense to most, you factor in the wind and shorter distance flight in strong headwinds can be more time than a longer distance with lighter winds. Going E to W across the atlantic you factor mostly headwind, and W to E you seek favorable tailwind.
FredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 25
Reply 2, posted (3 years 2 days 15 hours ago) and read 2892 times:
1) Winds, as pointed out by planeguy. That's most of your time difference.
2) Great circle routes. The most direct route goes over the middle of the UK and Ireland and never over France. They do not appear straight on your normal map, but they are the straightest route when flying. Check it out in Google Earth.
3) The GC distance is around 4550 nm. If you instead go all the way to the southern tip of Sweden and then on to Washington, it's 4620 nm or so (as measured in GE). That's 70 miles added distance, or mere minutes at airliner cruise speeds. Diversions typically add less distance than you'd think.
I thought I was doing good trying to avoid those airport hotels... and look at me now.
Yikes! From Canada, joined Oct 2001, 284 posts, RR: 1
Reply 3, posted (3 years 23 hours ago) and read 2648 times:
Every day, twice a day, the Air Traffic Control units responsible for the North Atlantic Track System (NATS) publishes east & west-bound "canned" tracks, each identifiable by an alpha letter - lower letters being eastbound; higher letters being westbound.
The tracks are designed for "best time" or shortest time enroute. On that particular day, the shortest great circle route might have actually taken much longer than the route you flew because of environmental impacts.
Starlionblue From Greenland, joined Feb 2004, 17494 posts, RR: 66
Reply 4, posted (3 years 23 hours ago) and read 2645 times:
Quoting skopsko (Thread starter): From IAD to IST, the flight path was much more reasonable (going through Germany) and hence the flight was 2-3 hours shorter.
The differing flight paths definitely did not make a difference of 2-3 hours. That's mostly due to the winds in the jetstream. Going from North America to Europe, airliners can take advantage of winds of 50-200 knots. Westbound airliners avoid the jetstream and thus have a much lower groundspeed.
"There are no stupid questions, but there are a lot of inquisitive idiots."
rfields5421 From United States of America, joined Jul 2007, 7805 posts, RR: 32
Reply 5, posted (3 years 23 hours ago) and read 2645 times:
Yesterday there was a huge hump in the jet stream. Flights trying to cross the Atlantic anywhere much south of Vagar/ the Faroe Islands would have been flying head on into 150 knot winds 3/4 of the distance from the UK to Greenland.
Most trans-atlantic aircraft yesterday flew far more north than usual.