Heres something interesting that's happening to me. it all started earlier this week when i way flying my Alaska 739. I loaded up the FMC, put in my flight plan and got everything set up. then i went to the cruise page to view my computer calculated optimum cruise altitude. funny thing is that it was 200 feet above my maximum cruise altitude. like it said opt/max: 375/373. Now whenever i fly either the 738 or 739 i get this same opt/max altitude problem, always the same 200 foot difference. I dont know if anybody else has had this problem. its not terribly high up on the bug list if it is a bug. just something to take a look at. thanx in advance for any helpdavidinformation:Alaska 739KSEA--KLAXfuel: 19000 lbsOpt/Max: 375/373Qantas 738YBBN--YPPHfuel: 29000 lbsOpt/Max: 365/363

Though I didn't get that specific problem, I do get some calculation errors with opt/max calculation while on the ground. At the gate my FMC would say something like 370/390, even though I know the REAL opt should be 350 :) And sure enough, once I got in the air, the FMC changed it to 350.

I think the FMC would have calculated the OPT/MAX cruise altitude with respect to the present elevation on the ground.Once in the air the baro is set to STD so it recalculates the cruise altitude.Cheers,-Navneet-|www.precisionmanuals.com|-http://www.precisionmanuals.com/images/forum/800driver.jpg

Hi David,I have the same problem here. I'm flying a long flight with the B737-900 (OMDB-EHAM 2755nm). I'm sure I entered the correct weights and fuel. My optimum FL is now 337 and the maximum FL is 326.Jasper :-wave