st and East to West on this route of about an hour, but with these winds sometime blowing at over 200 mph this varation can be considerably more. So overall I would think that on a Great Circle route which is curved on a normal flat map projection it would be between 11 to 12 hours heading west from Manchester to San Franciso. It is pretty much the same distance from Heathrow to San Franciso and the time can range bewtween 9 and 12 .5 hours for that trip. Hope that answers your question.
Conway New Hampshire