Hi Guys,

Quick question,

When calculating the variable fuel I understand that it is calculated from the flight fuel. So when you are conducting say a search that incorporates variable reserves, but when you arrive at a destination with a TEMPO (holding) this is not factored into calculating the variable reserve.

However when calculating the safe endurance for PNR's (e.g. question N0 12 pg 4.52) when holding is required at departure aerodrome, the variable reserve is calculated from flight time + the 60 minutes holding (shouldn't it just be calculated off the flight time)

Hope this makes sense.

Cheers,

If you are dealing with fuel for a search, there is really no legal need to carry a variable reserve because a search is aerial work and not charter. However a question like this will stipulate what your company policy is and it might be that you are required to carry variable reserve fuel unless you are holding over an aerodrome. It is normal not to carry variable reserve for holding. You should remember that according to the CAR, it's up to the pilot or operator to decide what fuel reserves to carry, however the exam usually says that your operator has decided to operate according to the CAAP on fuel reserves.

Hi Bob,

Thanks for the quick reply and also for your books as they have successfully got me through every exam with only a couple more exams to go.

I understand, but just still a little confused sorry.

I understand holding fuel "because holding fuel is used after the flight has been completed it is not flight fuel.

Example on Page 4.31

"Flight fuel is 35 gal and the destination requires 60 min holding, minimum fuel at start up"

(flight fuel / variabel) + fixed + holding + taxi
(35 x 1.15) + 15 + 17.2 + 3 = 76

However for the PNR example on Page 4.49 it is

(Total fuel - taxi - fixed reserve - holding) / 1.15

(680 - 15 - 90 - 120) / 1.15
= 396 lts

How come the PNR is not

(Total fuel - taxi - fixed) = flight fuel
(Flight fuel / 1.15) - holding (as you are over the holding aerodrome)

(680 - 15 - 90) / 1.15
500 - 120
= 380 lts

Sorry if I am going around in circles.

Cheers,

The holding fuel is not flight fuel. So in the example you have given the correct approach is to simply treat the holding as if it was an extra fixed reserve.

(680 - 15 - 90 - 120) = 455. So 455 is 115% of the flight fuel.

So flight fuel = 455 ÷ 1.15 = 396.

In your working you have (680 - 15 - 90) ÷ 1.15, so you have taken out 15% of the holding fuel because the figure you divided by 1.15 includes the holding fuel.

Bob

Thanks Bob, I get it now. Looks like I was confusing myself over something pretty simple.

Fingers crossed for performance.

Cheers