2.
LO/ECON air conditioning
3.
Fuel Consumption Factor set equal to (1+FMS PERF FACTOR(%)/100)
4.
Drag factor set equal to 1.0
5.
Atmospheric conditions as close as possible to the ones used by the FMS
6.
Speeds as applicable
4.1.3. Determination of the actual aircraft performance
The intent of this paragraph is to explain how to use the IFP program to calculate actual aircraft performance.
4.1.3.1. Flight at given Cost Index Airbus recommendation is to use the HYBRID mode.
The HYBRID mode will perform the ECON speeds and fuel flow calculations. The fuel factor(s) have an influence on both types of items. The point is that two different fuel factor(s) must be used: -FMS PERF FACTOR to obtain ECON speeds -Monitored fuel factor to obtain fuel flows
In the IFP, only one consumption factor can be entered. The following gives Airbus recommendations to bypass that constraint. The FLHV is used during the calculation of fuel flows. Basically, the higher the FLHV, the lower the fuel flow. The whole idea is to modify the FLHV by a certain amount in order to compensate for the difference between the FMS PERF FACTOR and the monitored fuel factor, that is to say, to compensate the Basic FMS PERF FACTOR.
As a general assumption, one percent FLHV deviation results in one percent deviation in fuel flow. Then,
FLHV . FLHV
CORR ACTUAL
=.FMS _ PERF _ FACTOR(%)
FLHV
ACTUAL
where FLHVACTUAL is the actual FLHV FLHVCORR is the corrected FLHV .FMS_PERF_FACTOR(%) is the basic FMS PERF FACTOR in percent
Flight Operations & Line Assistance Getting to Grips with Aircraft Performance Monitoring
USING THE MONITORED FUEL FACTOR
Then,
FLHVCORR =.FMS _ PERF _ FACTOR(%) × FLHV + FLHV
ACTUAL ACTUAL
The IFP HYBRID mode should be used with the following assumptions:
1.
Corrected FLHV (see above)
2.
Air conditioning/Anti Ice as appropriate
3.
Fuel Consumption Factor set equal to (1+FMS PERF FACTOR(%)/100)
4.
Drag factor set equal to 1.0
5.
Atmospheric conditions as close as possible to the actual ones
6.
Cost Index as applicable
4.1.3.2. Flight at given speed (CAS/Mach) The IFP STANDARD mode should be used with the following assumptions:
1.
FLHV as appropriate
2.
Air conditioning/Anti ice as appropriate
3.
Fuel Consumption Factor set equal to monitored fuel factor
4.
Drag factor set equal to 1.0
5.
Atmospheric conditions as close as possible to the actual ones
6.
Speeds as applicable
4.2. The FLIP program
This paragraph describes the way to use the FLIP program with the different fuel factors, depending on the objective.
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