Fuel Tankering Formula

[Mister Geezer]

Just wondering if someone could perhaps offer some wisdom. I am convinced I have missed something?

My understanding of checking if tankering is worthwhile or not is by doing the following:

1 - Calculate excess fuel to be tankered

2 - Calculate the fuel that will be burned to carry this fuel

3 - Use the result of 2 and divide that by 3 to calculate the percentage of excess fuel that will be burned

4 - Use the result of 3 to compare against the fuel price difference as a percentage between departure and destination airfield. If the price difference is less than the result of 3 then tankering is not suggested and vice versa.

Thanks

[kanetoads]

Are you in a position where you can fly optimal routes/alts?

[RAT 5]

In olden golden days, when more decisions were made by informed crews, we did the following:

Departure airfield = 100%

destination = XYZ%

Time of flight in hours x 2.5% = ABC% & is cost of carrying extra fuel, assuming increased takeoff weight due to extra fuel. If ABC% < XYZ% = tanker.
Now we don't have the % data; we just have a yes/no list. The difference could be a little or a lot and you could make an informed judgement. Now 1% or 10% difference shows up the same yes/no.

[Mister Geezer]

kanetoads:

We fly short haul and some sectors can be quite short so we generally fly the most efficient levels and routes that we can.

RAT 5:

Thanks for that. We are a single aircraft corporate operation so we have a lot of say in how fuel is uplifted.

Time of flight in hours x 2.5% = ABC%

Would it not be the fuel burn multiplied by the factor to carry fuel?

[latetonite]

Extra burn for more fuel onboard: 2.5% x extra fuel x trip time in hours. Simple. i often compare the result with our FPL where the extra burn for more fuel is calculated and given as a reference for the pilot, and it matches about every time. (B737NG)

[BOAC]

The only variable is in the burn factor. Memories fade but I think I used to use 3.5 for 73NG and 4.5 for Classic. It also all depends on your company 'telling' you what they actually pay for fuel where, and that can sometimes be prized information! It is very easy to write a spreadsheet to determine tanking taking in all factors - next sector fuel, MLW. next MTOW, fuel costs, tank capacity, mother's maiden name etc etc. once you know the factor and the fuel costs.

[RAT 5]

Mr. G. My apologies. I see my error. ABC% should read 100% +/- ABC%. This is then compared to the % of fuel price at destination. To use this calculation all destinations need a fuel price relative to 100% at departure field.

[latetonite]

BOAC, the 3.5 % probably assumes you are going to operate a few thousand ft lower due extra weight, very conservative.

[BOAC]

Who knows? I have just 'revisited' the spreadsheet I wrote 'in my last company' for tanking on the 737NG and Classic and 3.5/NG and 4.5/Classic were the company published penalties. You do, of course, often cruise at a lower level. One works on what the company tell you.

[BlankChecks]

OP - You need flight planning software to run scenarios...optimum alts, power settings, differing weights...

I just ran a West Coast Hawaii scenario on Flight Plan.com that was so completely useless, it's hard to believe that anyone would trust it. It's like swatting at flies with a baseball bat, not very precise.

[Microburst2002]

1-In your computer flight plan, check the extra fuel burnt per each extra ton of weight. Most CFPs have that.

2-Then compute the total extra fuel burnt for the maximum tankering you can make taking into account LW and TOW.

3-Then find the factor. For instance, if original trip fuel was 10,000 kg and you need to burn 200 kg to carry the extra fuel, then the factor is 2%.

4-Now you can say that any tankered fuel costs the fuel price plus a 2%. If the fuel at destination is more than a 2% more expensive tankering is advisable.

[zomerkoning]

There are multiple ways to calculate the need for tankering fuel, it also depends on which type of aircraft you are flying.

With us for example in the winter we use a different method than during the summer. The reason being that during medium to long sectors full fuel tanks can lead to induced icing and you then require de-icing at destination, which costs time and money. The total being more than the money you saved on the fuel bill by tankering.

Some many variables, and all of them becoming more important every day with the rising fuel costs. When I started we have 15 minutes of company fuel extra for every leg, that has now been reduced to 0 and variable contingency (with minimum 5 min) calculated for the destination and route.