Question about fuel

Hello IFC, I have a question regarding fuel

I am currently doing a flight from Atlanta to Icheon on a 747-9 and at ATL I made sure to fuel the aircraft the Estimated flight time said 23 hours remaining and now 4 hours into the flight The remaining fuel I have is for 7 hours and I’m supposed to land in 8 hours. Why is the fuel decreased?


Hello, what speed are you flying at? If you’re flying too fast, or too high, that might be a reason why you have burned fuel faster than expected. It does also appear that you are flying a Boeing 747-800, which I do think has a shorter range than the Boeing 787-9.

Edit: The choice is up to you, but if you consider diverting, I would suggest diverting to Fairbanks International Airport (FAI/PAFA). It’s runway comfortably accommodates a Boeing 747-8.

Check on Infinite X Im currently over Canada and close to Alaska My callsign is Korean Air 175 Heavy

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Im travling at Mach 0.92
Altitude, 38,000


I may not be able to divert to PAFA because its an overnight flight

Mach 0.92? That’s way too fast.


What speed should i go?

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0.85 for a 787

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Im on a 747-9

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0.85 for 747s. And drop to FL280 you’re way too high.

I would say mach 0.81-0.84. Aren’t you overspeeding?

If you see that you can’t make in time, consider diverting.

Im not overspeeding

Its still way too fast

Standard cruising speed is from .75 to .82 Mach. Make sure that you do not have any flaps or anything similar that induces drag and hirer fuel burn. Another trick is if possible change the winds or find a tailwind. As for 747-9 I think you have invented a new plane.

You’re not overspending but it’s inefficient. You need to slow down and drop altitude. You can most likely still make it.

If you don’t have the time to land now, execute a Flight Resume, come back whenever you’re ready and land.

Thank you so much

No problem. Happy to help!

I ran the numbers for you. I don’t know how heavy you are but at 50% load you’re burning 28000 pounds per hour at 0.92 at FL380. Drop down to 0.85 and FL280 and you save 6000 pounds of fuel an hour. If you take action quickly you should be able to make it.

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I believe that’s right. As long as you fix your aircraft’s inefficiencies quickly, you might escape the diversion. Worst things worst, there’s also Japan that you can divert to later on.

Got a few wise words.

Never trust the infinite flight estimated flight time for fuel. It doesn’t adjust for payload, cargo, altitude, headwind, tailwind, etc. I suggest simbrief 😜