Final reserve fuel is the minimum fuel required to fly for 30 minutes at 1,500 feet above an alternate aerodrome or, if an alternate is not required, at the destination aerodrome at holding speed in ISA conditions. Some Regulating Authorities require sufficient fuel to hold for 45 minutes.¹
There are two ways to calculate Final Reserve Fuel: Constant and Time-Based.
The choice of Final Reserve Fuel calculation can be set up in Aircraft settings by following these steps:
Select ‘Constant’ from the ‘Final Reserve Calculation’ drop-down list.
Specify the amount of fuel that the system will take into consideration while performing the Final Reserve Fuel calculation.
The Final Reserve can be specified separately for instrument and hybrid flight types (IFR, Z, and Y flight types - I/Y/Z) and a VFR flight type.
In the example below the calculation type has been set to Constant, and the amount of final reserve fuel for an IFR flight has been set to 3.00 US gallons, for a VFR of 4.50 US gallons.
The Final Reserve can be seen in the Loading Summary table and in the Flight Log:
Select ‘Time-Based’ from the ‘Final Reserve Calculation’ drop-down list.
Input the required number of minutes and choose Flight level from the drop-down list. The amount of fuel needed for the flight will be automatically calculated.
It is also possible to set separately the ‘IFR Final Reserve’ and ‘VFR Final Reserve’.
Users who have aircraft with the downloaded advanced performance data profiles can select the Power Settings for IFR and VFR Final Reserve from the available profiles in the drop-down menu.
The following altitude selection is available: 1500 feet (which is set by default) and Cruise Flight Level.
Once these steps are completed your planned flights will calculate the Final Reserve Fuel and incorporate these results into the Flight Log.
¹ Skybrary, Final Reserve Fuel / Fixed Reserve Fuel / Holding Fuel