-
Adjustable FLHV
-
Adjustable thrust factor -Adjustable fuel consumption factor
Flight Operations & Line Assistance Getting to Grips with Aircraft Performance Monitoring
USING THE MONITORED FUEL FACTOR
4.2.2. Simulation of FMS predictions
The intent of this paragraph is to explain how to use the FLIP program to reproduce actual FMS predictions on board the aircraft.
4.2.2.1. Flight planning at given Cost Index
The Standard Flight Planning with FMS speeds should be used with the following assumptions:
1.
ECON speed selection (Managed mode)
2.
FLHV set equal to 18400. BTU/LB (as in the on-board FMS)
3.
LO/ECON air conditioning
4.
Fuel Consumption Factor set equal to (1+FMS PERF FACTOR(%)/100)
5.
Thrust factor set equal to 1.0
6.
Atmospheric conditions as close as possible to the ones used by the FMS
7.
Cost Index as applicable
4.2.2.2. Flight planning at given speed (CAS/Mach)
The Standard Flight Planning with FMS speeds should be used with the following assumptions:
1.
Use Selected mode with FMS regulations
2.
FLHV set equal to 18400. BTU/LB (as in the on-board FMS)
3.
LO/ECON air conditioning
4.
Fuel Consumption Factor set equal to (1+FMS PERF FACTOR(%)/100)
5.
Thrust factor set equal to 1.0
6.
Atmospheric conditions as close as possible to the ones used by the FMS
7.
Speeds as applicable
4.2.3. Determination of the actual aircraft performance
The intent of this paragraph is to explain how to use the FLIP program to calculate the actual aircraft performance.
4.2.3.1. Flight at given Cost Index Airbus recommendation is to use the Standard Flight Planning with FMS speeds.
The Standard Flight Planning with FMS speeds will perform the ECON speeds and fuel flow calculations. The fuel factor(s) have an influence on these two 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 FLIP, only one consumption factor can be entered. The following gives Airbus recommendations to bypass this constraint.
Flight Operations & Line Assistance Getting to Grips with Aircraft Performance Monitoring
USING THE MONITORED FUEL FACTOR
The FLHV is used during the calculation of fuel flows. Basically speaking the higher the FLHV, the lower the fuel flow. The point 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(%)
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