What If - Problem

[P-air]

Have noticed a problem with Load 21.2, with regards to using the What-If function for performance planning.

Currently, when entering a What-If scenario, if you choose an altitude 500 feet or higher than present altitude, the What-If scenario will work fine.

If however, you try to do a What-If maintaining the same altitude, or lower, the fms will use the next Hard Altitude for the Basis of its altitude calculations.

Example, if an approach or Star is not entered, it will normally use the Airport Elevation. So what the result will usually be is, that the aircraft will base the cruise times and fuel burns on what is likely to be sea level.

One Solution around this, is put in a PBD a few miles prior to TOD, and then enter a hard altitude (your present cruise altitude) forcing the FMS to then conduct the What-If Scenario, at the next known Hard Altitude. (This case now being Cruise Altitude)