> planes that are simply too old

Planes don’t really age like that, at least not if they’re serviced. They’re constantly being rebuilt and inspected.

The only reason airliner fleets churn as much as they do is fuel efficiency and maintenance standardization.

Nit: at some point you start getting metal fatigue issues (see Aloha Airlines Flight 243) but in general yes: fuel efficiency and fleet standardization.

Also airliners usually just become cargo planes for quite a long time before retirement. Eg. there's a bunch of DC-3s still being commercially operated. Jet engine noise regs killed a bunch of early jets, but older prop aircraft are still going strong.

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labcomputer 7 hours ago | parent | next [-]

> Also airliners usually just become cargo planes for quite a long time before retirement.

Yes, but that's a function of how fuel economy and capital impact the overall economics.

Cargo = (usually) one flight per night.

Passenger = (usually) many flights per day.

It's important for cargo airlines to have low capital costs for an asset that spends a lot of time not making money, but it's important for a passenger airline to have low operating costs for an asset that's burning fuel all the time.

Passenger airplanes are repurposed for cargo when newer, more fuel efficient airplanes come on the market.

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JumpCrisscross 11 hours ago | parent | prev [-]

> Nit: at some point you start getting metal fatigue issues

Good point. The B-52 doesn’t pressurize the whole fuselage. Just the crew compartment.

> airliners usually just become cargo planes for quite a long time before retirement

Out of curiosity, do they not pressurize the cargo hold?

	▲	bri3d 10 hours ago \| parent [-]
		> Out of curiosity, do they not pressurize the cargo hold? Well, the DC-3 is a fun example, because it wasn't pressurized to start with. But no, normally converted freight aircraft are fully pressurized; it's more expensive and more intrusive to redesign the plane to have a cockpit pressure bulkhead than it is to just leave the whole thing pressurized. There are some exceptions like the Beluga, usually due to door design constraints (at some point, making a cockpit pressure bulkhead becomes easier than making a giant pressurized door). This trend in retrofits might change; flat aft-pressure-bulkhead retrofits are becoming a thing to increase cubic footage capacity, and at some point someone might decide that the effort required to engineer and certify a cockpit bulkhead would be worth some advantage in door design or cargo capacity in a broader sense. But for now, they're usually fully pressurized. The main reason why planes get a second life in freight is that freight carriers have _way_ more options for utilization; they fly fewer hours overall, hold the plane until it's completely full, and utilize different airports and routes. A loud, inefficient plane is OK to fly twice a day between two fixed airports with no noise restrictions, but useless to a passenger carrier who wants to make four or five turns between whatever airports are necessary and doesn't have guaranteed utilization to cover the overhead - right back to your original point, which I don't think anyone was really disagreeing with.