Originally Posted by
The dude
Is this a new FMZ unit or has there been changes to the software made recently? I've seen that on newer A/C and if I remember correctly it is because the FMS doesn't have enough flights in the system to compute an "average"...if you will. After enough legs the Full Perf. feature will always be available. Could be wrong but that's what comes to mind.
This is possible but it sounds like on occation Jetflyger initially has full perf until some time during the flight. I know the box is designed to automatically revert to CURRENT GS/FF if the data becomes invalid for some reason.
I might look into why the data might have become invalid either through crew inputs, a set-up issue seeing bad data (cross-talking), or an internal issue with the box.
Kevin