View Full Version : FMC Correction factors
Hi all,
On the Boeings and Airbus, Embraer etc, is there a limit to the entry that can be put in the FMC for amending the drag factors or the fuel flow factors? I presumed that it was 9.9% but I note that at least one FMSCDU emulator permits larger(and smaller :)) entries.
Does anyone in the FMS world have a good answer on that matter, it is a point of some interest with a test flight I just flew.
Please don't mess with this in a real plane, this is for those in the Smiths/Thales/Honeywell area, etc.
regards
FDR
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RocknRola87
25th Nov 2022, 12:52
As you pointed out, on the B737NG the AMM states allowable DRAG FACTOR entry range is -9.9 to 9.9 . The same apply to the F-F fuel flow factor .
As you pointed out, on the B737NG the AMM states allowable DRAG FACTOR entry range is -9.9 to 9.9 . The same apply to the F-F fuel flow factor .
That was my recollection for the whole range of Boeings, from the B737 through 744, 75, 76 77 and the 78. Was surprised that the A320 seems to accept the higher values, which is helpful to me, sucks for Boeings.
RocknRola87
25th Nov 2022, 13:22
Had to deal with this figure once, when the FMC calculated a relatively low arrival fuel at destination, reviewed all parameters ground distance , entered winds & so on .. finally jumped to PERF FACTOR page as las resort , found a 9.9 figues on the Drag factor 😅. As you pointed out earlier, one must not plays with those figures.
Is it possible for someone in the SIM to check what the FMCGS will do please for the A320/330/350/380? I need to be able to enter /-31.6% or /-31% and I believe the Thales FMGCS will accept that, I have discussed the matter with Smiths and Honeywell, and they are prepared to look at the mask change to suit my STC series, the alternative is a change to the ePDB ASCII to provide the new data set rather than the bias. You can see why this is necessary if you watch some of the video of one of my baby jets in test at www.delta-burn.com
regards,
A320 and A330 FMS AMI configuration files from Honeywell specify that the range of the Perf Factor that can be entered is from -9.9 to +9.9.
And lets face it. If your flying an airplane that has a higher perf factor then something somewhere on that plane needs to be brought back to spec.
pineteam
15th Apr 2023, 08:34
Is it possible for someone in the SIM to check what the FMCGS will do please for the A320/330/350/380? I need to be able to enter /-31.6% or /-31% and I believe the Thales FMGCS will accept that,
regards,
I just tried now on the real aircraft ( A320 with Thales FMGCS). As mentioned by Nnco, the max value is 9.9 for both the Idle and Perf factor.