Matthew
You must go through at least once through Getting to grips with performance and FCTM.
Wind entries should be made for as many levels as possible to reflect the actual wind and temperature profile. This will ensure that the FMS fuel and time predictions are as accurate as possible and provide an accurate OPT FL computation. In cruise if wind difference is more than 30kt/30degrees modification at two flight levels 4000ft below and 4000ft above the current FL should be done. FMS creates a forecast model from pilot entered winds and a creates a predicted model by adjustment with current winds.
In GTG with PERF old figures for 320-232 specific range penalty for cruising at +2000 above optimum are 1.4% and 2000ft below 2.1%. Similarly - 4000 will be 6.2%. They are different for each model of A320.
Last edited by vilas; 25th Sep 2016 at 08:01.