Apart from ZFW, CRZ CG and the PERF FACTORS on the MAINTENANCE page of the FMC, what else affects the MAX ALT calculation?
I'd always thought once airborne, MAX ALT would always go
up assuming you didn't fiddle with any of the above factors...
However, there I was climbing away from CWL yesterday watching the MAX ALT, and having touched nothing, it went
down.
What might be the reason for that? Perhaps a VNAV performance iteration that resulted in a computed ECON TGT SPD that was a little higher, with the corresponding effect on MAX ALT? What other factors affect the MAX ALT calculation?
Cheers.
