Originally Posted by
c1223
Welcome to FT.
For obvious reasons BA are currently not flying over Russia. This means the routing is relatively inefficient. Usually the best route for the winds on BA8 from HND to LHR is to head east over Canada as that usually results in the strongest tailwind. As you noted, occasionally it flys back westbound instead. It is almost always due to the prevailing winds.
It’s probably due to the weather at the ETOPS alternates in Alaska and Northern Canada not meeting the requirements, it’s hardly ever due to the prevailing winds.