What’s wrong with 747?

Hello. When i tried to fly a long-haul flight on a 747-8, i planned fuel with fuelplanner, but actually that wasnt enough, and i just ran out of fuel.(acft was below MTOW). I made some tests offline, and find out that 747 with 0 winds needs 6h more fuel to fly, but that’s doesn’t always work. After few time i had an idea to put off pax and cargo, so my plane had only fuel aboard. And guess what? That wasn’t enough! Guys who’s flying on 747 in IF, how do you do it and how do you plan fuel?

So I have a few questions in regard to this.

First, what is your flight path (start and end is sufficient I don’t need the whole thing)? What is your cruise altitude and how fast are you flying? What was your weight at takeoff? Are you step climbing or just going straight to cruise? Also, have you trimmed the aircraft properly? I’ve flown the 747 long haul a number of times, and done many more long hauls with other aircraft and have never had an issue of running out of fuel, but it is really easy to burn a lot of fuel if you don’t take the proper considerations, especially with a heavy craft like the 747.

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I’m flying only real life flights, so my path must be suffisant. I’m flying on FL330-390 for my LH flights, using the Mach speed that i find on Wikipedia. My weight is also correct, and im climbing straight on the cruise altitude. Actually, I’m grade 3 and i have 278K of xp, and I’ve never issued the same problem on other aircrafts. I’m really surprised with this plane’s behavior. I tried also to trim the plane, but it doesn’t helps(
Anyway, thanks for replying

So with heavy aircraft it is super important not to climb straight to your cruise altitude but use a method called step climbing. This is a good topic to read for it:

Also, trimming the aircraft is definitely important as well. Another good topic from Deer Crusher on this:

You are right in saying that if you are following a real flight plan then you shouldn’t be running out of fuel, but if you aren’t taking the steps that the actual pilots will be taking then you will absolutely run out of fuel :). Definitely look into step climbing because 747’s have a really hard time maintaining cruise altitude when they are heavy, and so you are likely using way more fuel than you should be for that point in the flight. Hope this helps!

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Ok, thank you! I’ll try to do whatyou said, i hope it will help! Thanks

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One other question. Where do you plan fuel for your fligths? I’m using fuelplanner.com

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Fuel estimates are based on average fuel burn, or something thereabouts. It’s an estimate. There’s no way to say “you have exactly this much fuel” as there are to many variables.

You’ve already claimed 0 wind, which would be a miracle at altitude, but even presuming the winds were deathly still at altitude, there are still other considerations. It seems you eschewed step climbing. Your V/S plays a role in fuel burn. Weight. Speed. Any number of thing really. There are too many to find the exact cause without watching your fuel burn at every point of the flight in conjunction with your settings and winds and whatever else.

Low fuel shouldn’t be a surprise, as your fuel remaining is calculated at every moment of flight, and the info can be made readily available at the bottom of the screen.

I would ask one question, though, regarding your route. When you say you’re flying real routes, do you mean you’re flying real flight plans, or flying directly to your destination without a flight plan in between? Direct lines are actually longer distances than utilizing Great Circles, etc, due to the curvature of the earth. The longer the flight, the greater the difference.

But, again, without all of the necessary info, there are way too many variables to know.

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If you use simbrief or fpltoif.com to plan your flights, not only will this get the fuel right but will also tell you exactly when to step climb and by how much.

Always on the 747 when you are on the initial climb the fuel consumption is high and it appears that you won’t have sufficient fuel, however once you have burnt off some of the weight the consumption improves and you will land with same amount of fuel that simbrief told you that you would do.

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Yes, i know all this stuff, and surly im fling with a flightplan, and i observing my fuelflow etc.

So what route did you attempt to fly? Also how far out from your destination did you run out of fuel?

I attempted EDDF-RJTT and first time I’ve tried, at beginning of the flight on cruise FL, i observed a difference of about 3h with fuel remaining and flight time. So next time i added 6h more and that worked

That’s a route I’ve flown many times. I personally like to fly EDDF-RJBB with the 747-400 more, but it’s alsmost the same thing.

Anyways, in the first phase of your flight, you’ll see a difference in fuel. Most likely you’ll find yourself with less fuel than required to get to the destination as the 747 itself is a heavy aircraft and requires more power to take off and being heavy early on, uses more engine power to stay in the air, it will consume more fuel than it will later on in the flight.

My next follow up question is: How do you step climb?
What are the altitudes do you cruise at, from your initial to final altitude. What step do you take, like FL330 to FL350 or FL330 to FL370, etc…? And for how long, approximately do you stay at those altitudes?

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Personally I don’t use a fuel planner, I’m kind of a nerd so I enjoy doing those parts myself! I have meteorology training so I tend to just look at prevailing wind patterns, make predictions about how those winds may change in flight, and look at barometric pressures and such, and then I make decisions about fuel. The features that Wunderground picked up from Intellicast are particularly useful if you would like to do this yourself. That being said, I’m sure fuelplanner does vastly similar things in much shorter amounts of time, so that shouldn’t be an issue if you are using it.

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I usually never use a fuel planner. But when doing a long haul I go on a full tank and if I am above the minimum landing weight I just dump fuel while descending. Unrealistic, but I do not want t risk stalling mid air and forcing myself to restart a flight. Though I do use a decent calculator and Flight Plan Database.

If you always take a full tank then you will be at a much higher chance of stalling, especially if you are not planning the flight correctly with speeds and step climbs. Fpltoif.com is your friend!

Trim trim trim. Yes. 👍

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