I would be very surprised if JFK-LHR is one of the most profitable routes. Ever since the Asian downturn there has been a whole heap of extra capacity on those routes which is just starting to be dissipated (both DL and UA have a few new Asian routes starting April 1, 2001) and there have been crazy sale porices on these routes, eg $228 roundtrip. The fact that the discounts are so low is probably an indication that they're having trouble filling the planes, and thus that the load factors (which govern profitability) are not great. Just a guess though, or course!!!