Safelife,
Yes i have been keeping an eye on the winds and it doesnt appear to be the cause. Yesterday east bound strong tailwind opt and max were the same and on the west bound the same daywith strong headwinds up high it still had opt and max together.
We tried ci changes and both opt and max remained together from ci 0 to 60. In old airlines with same engines we would fly ci 40 and there was always a split of several thousand feet.
Interestingly, the Qrh rec max agrees with the fmc each time I have checked but the qrh opt is often 2-3000 feet less than the fmc opt.
My take thus far is that there is something odd about the fmc opt alt predictions in these aircraft.
Flight detent, fms setup. Honeywell fms 2