FMC MAX ALT Calculation

[dartman]

without digging into the books on this. When you are on the ground, the Max Alt, performance numbers are based on the manually input ZFW, GTOW, and C of G. This will give you a Max Alt of xxx.x Once airborne, the C of G defaults to a conservtive forward position, and will give a different lower figure for Max Alt. Assuming you haven't fiddled with anything else, as in the original question, you can override this cruise default C of G, with the actual C of G based on ZFW C of G, and FOB. This will give, all other things aside the Max Alt. And yes, changing CI will affect the MaxAlt.