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Comment by jahabrewer | Hacker News Reader

> The max takeoff weight of a Boeing 787 is 50 tons more than it's maximum landing weight

I honestly don't know, but could this be part of the design simply because the engineers know the plane will weigh less on landing? Seems like that design would change if so much mass from fuel was no longer lost/burnt.

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This, but the reason it's engineered that way is because landing gear face far higher loads on landing. During takeoff, landing gear essentially only have to support the weight of the aircraft. During landing, the gear have to arrest the aircraft's descent (which may be momentarily 3 or 4 g's of acceleration if the aircraft encounters turbulence while landing); and then they need to brake the entire weight of the plane within the remaining length of the runway, which is a high loading in a different direction (along the aircraft's longitudinal axis). So maximum landing weight is set by the landing gear, while maximum takeoff weight is usually set by the wings and engines.

I didn't realize that most of the braking on landing was handled by the landing gear. I'd always assumed that the obvious sound of the engines reversing when we landed did most of the work, but some casual googling suggests that it's only supplementary, to reduce the load on the landing gear.

https://www.pprune.org/archive/index.php/t-379610.html is interesting :-).

Also, https://aviation.stackexchange.com/questions/1219/for-large-... .

The stronger the gear needs to be, the heavier it becomes. Planes are optimized for safety first and foremost, but weight is a very close second. Heavier plane = more batteries = more weight = more batteries etc.

yes and no, because now it's a pain in the butt when there is a takeoff issue. If there is a tail strike, an engine issue on take off, or a passenger emergency early in the flight, now they have to loop around in circles for hours with a damaged airplane before landing. Or they have to dump fuel, but they do it extremely rarely, because most planes can't even do it, and it's a pain in the butt and actually quite slow for the planes that can do it.

here is an example: https://www.youtube.com/watch?v=VSq9r05lVTo

and because fuel dump is only allowed above 4000ft/1300m.

It is way more complicated than just altitude, with zones and procedures, incredibly long checklists and a bit of maths. But a plane that can't reach 4000ft is probably in a mayday situation, and there is absolutely no time to try to dump fuel, it's a slow procedure.

All aircraft landing gear are certified for landing at MTOW, they just need inspected afterwards before the plane can re-enter service. The fact that frequently the captain's judgement is to prefer to land at a lower weight is a separate issue.

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