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Old 03-29-2008, 04:02 PM   #7 (permalink)
Yariv
 
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you guys are talking about two different things. the only thing the FMS learns is the specific performance of the aircraft you're in. this means fuel flow and resulting speed at different altitudes.

The paragraph from the CFM doesn't take into account the programming error in the XR FMS which gives you FL333. it's true that the FMS will wait for you to climb to the cruise altitude in the perf init (which is why you need to change it if you don't plan on climbing that high) but the FMS will continue to use data for FL333 even after you climb above it due to this error. it basically sees 333 as the highest the aircraft is capable of at the speed entered. to change the cruise altitude, change the cruise speed first, as was mentioned here earlier.
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