Hi,

Could anyone tell me how the final reserve for jets is calculated?

I know it's the fuel to fly for 30 minutes at 1500ft AAL in ISA
conditions at holding speed... But what weight do you use? Do you
assume that contignency fuel is burnt (so gross weight = TOW - TRIP
fuel - ALTN fuel) when starting the 30' holding and is it 1500ft above
the elevation of the destination alternate or above the destination? I
checked it in 2 publications. They stated the opposite...

Thanks a lot and Merry Christmass, Happy 2005 and many great landings.

Tim

(Tim) wrote

> Could anyone tell me how the final reserve for jets is calculated?
>
> I know it's the fuel to fly for 30 minutes at 1500ft AAL in ISA
> conditions at holding speed... But what weight do you use? Do you
> assume that contignency fuel is burnt (so gross weight = TOW - TRIP
> fuel - ALTN fuel) when starting the 30' holding and is it 1500ft above
> the elevation of the destination alternate or above the destination? I
> checked it in 2 publications. They stated the opposite...

Tim, as can be seen in the following regulation, one considers the
contingnency fuel to have been used. This is arrived at by following
the sequence of steps in arriving at the fuel required.

Hold fuel elevation is computed above the alternate airport.

Of course...this is only true for Part 121 International Operations.
You really didn't give us enough information for the question.....
"jets" is too generic.

Section 121.645: Fuel supply: Turbine-engine powered airplanes, other
than turbo propeller: Flag and supplemental operations.
(a) Any flag operation within the 48 contiguous United States and the
District of Columbia may use the fuel requirements of §121.639.
(b) For any certificate holder conducting flag or supplemental operations
outside the 48 contiguous United States and the District of Columbia,
unless authorized by the Administrator in the operations specifications,
no person may release for flight or takeoff a turbine-engine powered
airplane (other than a turbo-propeller powered airplane) unless,
considering wind and other weather conditions expected, it has enough
fuel—
(1) To fly to and land at the airport to which it is released;
(2) After that, to fly for a period of 10 percent of the total time
required to fly from the airport of departure to, and land at, the
airport to which it was released;
(3) After that, to fly to and land at the most distant alternate
airport specified in the flight release, if an alternate is
required; and
(4) After that, to fly for 30 minutes at holding speed at 1,500 feet
above the alternate airport (or the destination airport if no alternate
is required) under standard temperature conditions.


Bob Moore
ATP CFI
PanAm (retired)