An Airliner flies from LA to JFK in 5 hours. In the first 30 minutes the plane climbs to about 30,000ft. For the next 4 hours the plane flies at about 30,000ft. For the next 30 minutes the plane descends to JFK.

What % of the total fuel used for the flight is consumed in each of the 3 phases of the flight, i.e, the climb out, the cruise, the descent?

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    $\begingroup$ You forgot the 4th phase, at JFK: waiting 1 (or 2) hours to get a gate... Needs some fuel too, to keep passengers warm. $\endgroup$ – kebs Jan 6 '18 at 19:11
  • From this site by Boeing for the B737-800: fuel used for TO and climb = 2,300 kg.
  • From this site: fuel burn in cruise for B737-800 is 2,500 kg/hr
  • From this site: fuel burn at idle of a CFM56 engine = 300 kg/hr, so for the half hour descent two engines burn through 300 kg.

Total fuel for a 4 hour cruise flight is therefore 2,300 + 4 * 2,500 + 300 = 12,600 kg. Percentages:

  • TO & Climb = 19%
  • 4-hour cruise = 79%
  • 30-minute descent at idle: 2%
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  • $\begingroup$ Interesting how close my estimations were to those values. $\endgroup$ – Carlo Felicione Jan 6 '18 at 6:39
  • $\begingroup$ I know pretty nearly nothing about airplanes, but I do fly a lot. Surely the "landing" phase has to take significantly more than that 2%—flaps come out about 10 minutes before landing, and engine revs go up significantly. Once the plane actually lands, engines go on full power for braking. And then there's the obligatory circling at low altitude over Heathrow... $\endgroup$ – Auspex Jan 2 at 14:12
  • $\begingroup$ @Auspex Yes, you do not land with engines at idle. You want some engine power to control descent rate and increase safety if you cannot land. $\endgroup$ – Ville Niemi Mar 22 at 18:37

This one varies based upon selected power settings during climb, atmospheric conditions, aircraft loadout, winds aloft, etc. you would have to consult the performance tables in the operators handbook in question for this one. A good estimate would be about 85% of the total fuel consumed would be done during cruise flight, with around 10% used during taxi, takeoff and climb and about 5% consumed during descent.

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