I did four sectors across the pond on a 5 day back 2 back on a B747-400 with no problems.Two weeks later same type of 5 day trip on the 777.......four nose bleeds.
I never feel too bad when I get off the 747 or 767 but the 777!!.
There again BA tell us there is nothing wrong with them so it must be true!!
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WTDWL.
I await with helmet fitted replies from our flight crew to protect their baby!!.