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by Animats 530 days ago
Right. Pilot boards agree on this. It's clear that the plane landed halfway down the runway at high speed, no gear, flaps, slats, or speed brakes. A runway overrun was inevitable from that point.

Nobody knows yet why they landed in that configuration. Failed go-around? Engine out landing? Cut wrong engine after a bird strike? Loss of hydraulics? Too rushed for landing checklist in an emergency? All of those are possible. More than one may have happened. Wait for the flight data recorder data.

One article says the runway was equipped with EMAS, an Engineered Materials Arresting System.[1] This sits in the area just past the end of the runway, the part marked with painted chevrons. It's a thin layer of concrete over blocks of a material which includes foamed plastic holding pumice-like rocks. If a plane overruns the runway, the wheels break through the thin concrete layer and start pushing through the plastic/rock mixture, grinding the rocks into powder to absorb the energy. This usually damages the landing gear, but the rest of the plane survives. 22 planes saved so far.[2][3]

It didn't help here. The plane seems to have skidded over the EMAS area on its belly, instead of breaking through and getting the braking effect. The surface of the EMAS area has to be tough enough to survive jet blast on takeoffs, so it can't just be a sand pit.

[1] https://focustaiwan.tw/society/202412300010

[2] https://ops.group/blog/swerving-to-avoid-why-arent-we-using-...

[3] https://www.faa.gov/newsroom/engineered-material-arresting-s...

3 comments

> One article says the runway was equipped with EMAS, an Engineered Materials Arresting System.

> https://focustaiwan.tw/society/202412300010

Nowhere in that article says Muan Airpot has EMAS, it says a local official confirmed that Songshan Airport in Taipei has EMAS, following local concerns that Songshan Airport has an even shorter runway (2600m vs 2800m in Muan).

A thread full of armchair experts is already bad enough, please don't make it worse with seemingly well-supported misinformation.

Oh, you're right. Different airport. Sorry.

Muan does have the chevron markings on the overrun area, but that does not always indicate EMAS.

It does seem unlikely to me that a surface designed to give under the pressure of an aircraft wheels’ contact patch would function as designed under the comparatively lower pressure of an aircraft skidding along its belly.
It is clear that the main cause of the disaster was the landing in the middle of the runway and at excessive speed. However, if instead of that concrete wall there had been, for example, an extension of the runway filled with some material that could help dissipate the kinetic energy, perhaps the death toll would have been lower.