Philsquares From , joined Dec 1969, posts, RR: Reply 1, posted (8 years 11 months 1 week 3 days 5 hours ago) and read 2846 times:
There is no requirement to use the NAT system. During the winter months, it's not uncommon to go fairly far north, out of the NAT system. By doing that you are now on a random track. Some airlines use that system to minimize headwinds westbound during the winter months.
In addition, flights westbound to southern destinations don't have to follow the NATs either. In some cases it's quicker to just go on a random track.
However, there is no real thing such as a GPS track.
Petazulu From United States of America, joined Jan 2003, 701 posts, RR: 1 Reply 5, posted (8 years 11 months 1 week 3 days 5 hours ago) and read 2799 times:
On a recent flight in December on LH (FRA-JFK), there were really strong headwinds. The plane crossed the ocean farther south than I have ever seen. In fact, we can in straight off the tip of long island into JFK. Normally, we would have come down through Maine, VT, Newfoundland, etc. This time, we were never even close to those places the whole time. The flight was really long and bumpy (people were throwing up behind me and in front!). The pilot seemed to have a lot of vertical mobility in that he changed our altitude by many thousands of feet in an attempt to find clearer air (no luck btw!). My guess was that were on a unique track that day due to the unusual headwinds. It was clear that there were no other planes to tell us where the turbulance was or wasn't because the pilot seemed to have no clue.
We were probably outside of ETOPs range at times, but obviously, this was not a concern. Trailblazing across the Atlantic!
Philsquares From , joined Dec 1969, posts, RR: Reply 9, posted (8 years 11 months 1 week 3 days 5 hours ago) and read 2764 times:
In commercial aviation, the reality is Dispatch chooses the route. At most large carriers, the computer flight planning system looks for a minimum time track and goes with that. Theoretically, the NAT system should accomplish the same thing, but sometimes the data used by the airlines is a little more up to date than the NAT.
By far, the overwhelming majority of the traffic goes on the NAT system.