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Comment by amelius | Hacker News Reader

And how are these numbers in subsonic flights?

A flight from London to Singapore. How much fuel would it need without stops, versus how much fuel in the least-fuel case (but more-stops case)?

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One thing to take into account is that landing and taking off is very wasteful with fuel - jet engines use significantly more fuel when running in dense air and that doesn't include increased power for climbing.

I'm sure there's someone who can plug in numbers into a flight planner here, I'm interested in actual numbers.

OK, sure, I plugged this into a sim flight planner (http://onlineflightplanner.org/). This is on a Dreamliner.

    Heathrow - Changi: 63933 kgs
    
    Heathrow - Tehran: 26957 kgs
    Tehran - Changi: 39580 kgs

So at least based on this it's not too much of a difference, only 4% more with a stop. (Tehran looked to be roughly in the middle on the flight plan between London and Singapore.)

Interesting, I'd expect it to be a larger difference considering how much the carriers avoid stopovers.

Maybe the fees and organization of refueling tips the balance?

Carriers don't want to do a stop unless they're offloading and onboarding passengers, so they'd rather run one flight to the intermediary, and another direct.

Well yeah, we're talking a about WHY it's a problem for them to stop.

IIRC airframe lifetime is rated in pressurization cycles.

It adds a surprising amount of time. You have to descend, land, taxi to a fueling area, refuel, taxi, take off, climb. And that's if the local regulations allow fueling with passengers on board.

That's probably around 2 hours extra. And this in turn can require the plane to carry additional pilots and flight attendants.

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