Fuel Burn

Is that I do a large flight yersterday and the gasoline remaining was 8 hours. and the flight was 13 hours.😭 I was using an 787 at the Beggining I Cruise at 38000ft

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I can’t quite understand, can you give more brief information?

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Could u provide me with:
What aircraft were you using, what was your cruise alt. and speed, as well as what phase of the flight u were in

Please give the OP a chance to respond. We will end up 12 comments deep with the same regurgitated requests.

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Well that must mean either

A) you poorly planned out your flight and or miscalculated your fuel
B) You accidentally tapped fuel dump
C) You were too heavy for a specific altitude causing your N1 to be high resulting in quicker fuel burn

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Not true. As the fuel burns the fuel remaining will increase because the fuel burn decreases due to a lighter load.

Guys (@sk28, @xSev) hold on a second, read what @Levet said before you go on with your speculations…

I know well that you’re only trying to help but let the guy answer first with specifics about his flight before we indulge ourselves into what we think may have happened without knowing the full story.

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Is that I put 18 hours of gasoline and then it said that there was 6 hours I was climbing at 38000

We’re you in the climbing phase of the flight??

You meant the flight time based on the given fuel increases. Fuel remaining will decrease in regards to quantity.


@Rodrigo_Villalobos depending on your flight profile, weight settings and other conditions like headwind/tailwind you will see changes in the fuel used. IF gives you an estimated amount of flight time based on the amount of fuel onboard. These numbers are fairly accurate in most cases.

Which aircraft were you having issues with?

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Fuel doesn’t have a set time.

If you put fuel in your car, that’s not X amount of hours driving. If you’re driving on the highway with no traffic it’s one set of circumstances, and if you’re stop-and-go in city traffic another.

Same here. You can put in what will give you an estimated time, but if you’re flying high, fast, heavy, etc, that estimate will need to be adjusted.

Weight, speed, altitude; all of these things have an effect on fuel consumption.

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Thank you Tim, glad to see you around here again providing your insight and encouragement. The community missed you pal!

With that being said, a great way to know how much fuel you need is to use a website like https://fpltoif.com. Great way to plan flights :)

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If the flight was 13 hours, then you should not climb to 38000ft straight away, start off at around 32-34000ft!

See the ‘Guide to Step Climbing’ thread for more information…

It’s that simple guys!

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Exactly, long gone are the days where you could climb to final cruise altitude in the regions era.

FL290 - FL310 is a good inital cruise altitude. Also make sure that your speed and climb rate isn’t too high or too low. The link posted above will help you with all of that.

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You must cruise lower altitudes when you nearly full. Because lifting Power decreases when you climb high altitude and plane needs more energy to Cruise that altitude and increased n1. When increases n1 fuel flown increases too.

You should pack 1-2hrs of extra fuel so you don’t run out or are close to running out.
Heavy load = lower cursive altitude (FL290-340)
Light Load= Higher cruise altitude (FL350-400)

Weight altitude and Speed are all factors to fuel consumption

I usually have 4-5 extra for longhaul flights (over 8 hours) because for the climb and first part of cruise, the plane is pretty heavy and wastes more fuel

@Rodrigo_Villalobos

As many have said, fuel burn for long flights is influenced largely by weight, cruise speed, wind, and altitude:

Weight: This is a function of fuel, cargo, and passengers. Passengers can be estimated by using the seat capacity (found at seatguru.com or the airline website). Cargo is flexible, but for long flights it can be best to assume zero.

Cruise Speed: This article lists the proper cruise speed for each type of type of aircraft in infinite flight. Going faster or slower will have negative impacts on you endurance (how long you can fly with the amount of fuel you have) - Cruise Speeds

Wind: Winds can dramatically increase how long you need to fly to cover a set amount of distance. Tailwinds decrease required flight time, while headwinds increase flight time. Windy.com is a good source for information on winds (you just need to choose the right altitude on the right side). If your plane is moving in the same direction as the wind arrows, you are being aided by a tailwind and will complete the flight faster, and need less fuel to cover the same distance.

Altitude: One quick way to estimate what your cruise altitude should be during the flight is to use flightaware.com. See the picture for a more detailed explanation of what to look for to plan your altitudes during flight. More detailed information can be found here: A Guide to Step Climbing

There are more advanced tools like simbrief.com that can provide detailed information on weight, speed, wind, and altitude along with route planning, but they aren’t necessary to enjoy flying long routes in IF.

How to use FlightAware to plan stepclimbs:

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