# How much fuel

#1

Ok I am throwing this out to all dispatchers, Capt. F/O, and anyone who might know the answer:

How much would fuel would be burnt to fly an additional 1000 - 7800 lbs of payload around? I’d say an avg. trip of 2500 miles, on an MD-11.

I may not be getting all my info needed to answer this out there…which is why I am throwing it to someone who may know.

TKS

#2

If you know the fuel burn and weights for that trip, you could approximate the impact of a small amount of additional payload using the Breguet Range Equation.

#3

Many moons ago at Flight Safety the instructor told us the rule of thumb for that airplane, Westwind 2, was that you burned 35-40% of any extra fuel carried.
I looked at the Breguet Equation and it all looks like Greek to me. Maybe I’ll print it out and see if the Greek Cypriot family that lives here on the compound can translate it for me.

#4

Thank you for the info. I will look into that equation.

I also spoke with one of our crew last night and he showed me where on their paperwork a break down of how much fuel was needed to move 1000 pounds… I am going to post something on this next week and I’ll tell you the reasoning behind this question in the first place.

Again TKS

#5

I have not done all my homework on this but again, thank you for the input on this. What made me ask this question is f.o.d… Think about it, if you work on the ramp you see load sheets, daily schedules, and other random trash onboard aircraft. Now lets say that random trash adds up to a simple pound…or so. How much additional fuel is the aircraft going to burn every time it has a rotation.

In this day and age it pays to keep any and all undue payload off an aircraft no matter how small.

So going back to the top, if there is just 1 lb. per aircraft and you have 600+ aircraft, that is 600 pounds extra weight being carried in your system. If it takes 1 gallon of JetA to carry that pound now you are talking about undue \$ spent.

#6

You are right although I don’t think you would burn one gallon to haul one pound.
To add to my example of the Westwind, lets say for the sake of argument it has a 6 hour range with reserves. You have a 5 hour flight but fill up the tanks anyway. That means you have about 1500 pounds of extra fuel onboard, taking the instructors rule of thumb you will burn about 600 pounds more fuel on this trip. The range of the airplane and the trip length would have a bearing on your calculations.
The airlines have to weigh (pun intended) the cost of throwing all completely unneeded stuff off the airplane against risking making the passengers so mad they quit flying with you.

#7

I think a 1 for 1 ratio is a bit off. I’d have to do a bit more home work…I do know that a f/o on our B727 showed me on the paper work that to for each 1000lbs. for the 1:14 trip they would need an additional 77lbs fuel. Each trip being unique in length and aircraft…it would take a very long math problem to figure a ratio for the entire fleet.

Thank you porterjet for the 411.