There are several passenger trijets still existing - they are just not commercial airliners. Dassault for one is quite fond of the design; the Falcon 900, 7X and 8X are trijets, and I'm pretty sure the latter two are still in production. I wouldn't be at all surprised to see another trijet design from them probably around 2030.

The industry also responded to those crashes. For example, the El Al 1862 incident prompted a redesign of the engine strut that was subsequently mandated as a retrofit for all 747s.

And here's a more detailed description of that ground run incident. It also found that the failure was related to a design flaw, and mandated that aircraft be grounded for inspection and rework. https://skybrary.aero/accidents-and-incidents/b762-los-angel...

I'm not a regulator or aerospace engineer or anything like that so I can't really say which actions are or are not appropriate. But I do want to observe that these are all unique failures with unique risk profiles that can't all be painted with a single broad brush. All I was trying to do in the previous post was speculate on why a MD-11 failure could result in a grounding of the DC-10 and KC-10A as well. The first thing that came to mind is that I think those are the only remaining trijets of that general shape that are still around. Though I suppose another possibility is that they all share an identical pylon design or something like that.

It wasn’t failed. It was designed for a very specific reason and served that purpose well.

Once the reason went away, better designs took over.

They were designed to allow smaller jets to fly over the ocean further than a two engine jet was allowed (at the time). Airlines didn’t want to waste all the fuel and expense of a huge 4 engine jet, but 2 wouldn’t do. Thus: the trijet.

The rules eventually changed and two engine jets were determined to be safe enough for the routes the trijets were flying.

Using two engines that were rated safe enough used less fuel, so that’s what airlines preferred.

It was never designed to be used anywhere else as a general design. Two engines did that better.

> in which case, why have the tail engine at all?

"you know what this motorized piece of anything needs, less power"

-nobody, ever

Airlines operate to a much stricter standard than one in a million. If one in a million flights ended in a fatal crash, the US alone would see about 3 airline passenger deaths per day on average. The actual average over the past 10 years is under 0.02 deaths per day.

It's true that you can never get to zero. There's always a chance of some catastrophic failure. The lesson of modern airline safety is that you can get extremely close to zero by carefully analyzing and learning from the failures, which is exactly why these thorough investigations are done. The lesson from UA232 was to make sure one failure can't take out all of the hydraulic systems.

In this specific instance, "the engine fell off and took out another engine, leaving the aircraft with insufficient power to climb" is definitely not in the realm of "probabilities will get you eventually." It's very much in the realm of a mechanical failure that should not happen, combined with a bad design flaw that turns that failure from a mere emergency into pretty much guaranteed death.

Cargo is held to a lower standard than passenger service, but I suspect this will still spell the end of the DC-10 and MD-11, at least in the US. Engines will fail, and for an aircraft of this size, that needs to be survivable in all phases of flight just for the safety of people on the ground.

One other accident that was similiar, but these planes have had a ton of crashes for other reason.

The airforce retired the KC-10 in 2021.

The KC-10 went out of service last year. None are operating.

Most of the DC-10s in service in the US are used for fire fighting.

Sure, but if the engine grenades it can take it’s mounts with it and not shoot off like a bottle rocket in front of and over the plane, dropping down and under the plane instead (or even just sit there). Same with a compressor stall, or whatever.

It’s clear from the photos this wasn’t the engine failing at all, and in fact the engine kept producing a ton of thrust (probably until it ran out of fuel as it pulled it’s fuel line apart while departing the wing), and instead the thing that is supposed to be so incredibly strong that it restrains all this chaos failed.

Which is a pattern in this family of aircraft, but definitely not a common or normal thing in general eh?

Most aircraft, the engine stays with the airframe even if it turns into a giant burning pile of shrapnel and dead hopes and dreams.