[Scoundreller]

Also bad for fuel economy (and/or take a hit on cargo/pax/luggage carrying capacity): You have to take off with all that fuel even though you only need X / hr. Increased weight = more flying at a lower altitude (+ air resistance) until the fuel burn makes it safe to fly higher.

On shorter flights, you still have the weight impact from that empty tank and its infra. If they had to make a bump out on the fuselage, you have a permanent aerodynamics hit.

It's like permanently attaching a cargo carrier to your vehicle to carry more fuel. Fewer fuel stops, but more burn per mile. Can make sense in some situations.

The study of breaking up long-haul flights for reduced fuel burn is usually called: "Intermediate Stop Operations"

[literalAardvark]

You're still cutting a take off and landing so I can't imagine it'd be too hard to break even for flights where this increased capacity is helpful.

[nine_k]

Not only do take-offs spend large amounts of fuel; the fact of a landing and the servicing and refueling in the airport also cost the airlines.

Not having to land but instead having to carry some extra fuel while the engines work in their most efficient mode, and the air drag is low at a high altitude, should make airlines money. Else they won't try that :)

[schiffern]

Not just cost, but that limited airport "slot" represents (a slice of the) significant carbon emissions from building/operating the airport.

So even if you only care about carbon emissions, it can still make sense to skip the stop even if it causes slightly more total fuel burn.

[Ferret7446]

Semi-tangential, but this is why free markets are much more efficient than armchair experts.

Armchair experts won't correctly estimate all of these incidental costs nor the value of the saved time and overhead for everyone involved.

[Scoundreller]

It's basically the business model for some airlines like the Icelandic and middle eastern ones. Hub in the middle so you're not paying (potentially extra) staff to rest on an aircraft and/or hotels at each end. Be at home more rather than an out-station. Fuel up more where its cheaper. Do some "scissor" routing. Fly cheaper/less specialized aircraft. Not as easy for Qantas to get all those advantages. Cargo airlines do the same to carry more cargo.

[inigyou]

It's okay that different businesses specialise differently. Icelandic Air can do the two short hops and Qantas can focus on the super long nonstop routes, they're both valid. When companies in an industry become carbon copies of each other, they race to the bottom and the industry rapidly enshittifies.

[Scoundreller]

At some crossover point, the reduced fuel carrying (and max capacity requirement) makes up for the additional takeoff+landing. When we're talking ultra-long-haul, constantly fighting against more gravity due to incr fuel weight adds up to a lot of cost/burn.

[matt_kantor]

A compromise option is a technical stop[0] where the plane lands to refuel but passengers don't have to transfer to another aircraft (and often don't even have to deplane). I've never experienced one of these but it sounds way less annoying/stress-inducing than a connecting flight.

[0]: https://travel.stackexchange.com/q/1598

[sandworm101]

But it may allow operation of more routes without the need to refuel at both ends. That can be logistically interesting, paticularly going forward in a world of fuel crisis and uncertainty. Being able to deliver people in and out of Cuba without having to refuel in that country would be a market niche.

[Scoundreller]

Assuming you can regularly land with your fuel tanks half-full. You could overbuild everything to support that, but usually airlines don't want to pay for a niche design to support that. I'd bet military aircraft do get that treatment though.

[sandworm101]

It is actually rather common. Many airlines running shorter flights will not refuel at every stop. It saves time on the ground, which can be more valuable then fuel.

[Scoundreller]

rather common amongst (ultra)-long voyages?