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Why was there a wall near runway at S Korea plane crash airport?

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Re: Why was there a wall near runway at S Korea plane crash airport?

#251

Post by Xixi »

inoffensivename wrote: post #245
Xixi wrote: post #239

Earlier quoted context omitted.

You are making an assumption here, that I think is unreasonable: that the pilots (who have probably landed at this airport hundreds of times, it's not like they don't know the place) were expecting a large piece of reinforced concrete to be in the path of the plane. I'm speculating, of course, but pilots made the decision to land there (albeit in a very short amount of time). They probably made the reasonable assumpt…

> I'm speculating, of course People should stop doing this. Transport category airplanes are designed to suffer multiple failures and still be controllable. Why the airplane landed where it did, when it did, and how fast it did are the relevant questions.

I do not think speculations on HN are impacting the investigation in any way, shape or form, although I understand your perspective.

I do hope the investigation yields results that improve air travel safety.

Re: Why was there a wall near runway at S Korea plane crash airport?

#252

Post by WeylandYutani »

Aeolun wrote: post #111
Yeul wrote: post #47

I have been to airports whose runway end in the ocean, a swamp, a mountain and a 5 lane highway.

I’m worried about the ocean all the time, so it’s weird to think that’s actually the best kind of scenario.

Well depends on the weather conditions. All the successful plane ditches happened when there weren't any waves.

Re: Why was there a wall near runway at S Korea plane crash airport?

#253

Post by WalterBright »

hyperific wrote: post #224
WalterBright wrote: post #222

Why are we seeing random videos of this from bystanders? Why are there not video cameras constantly recording the activity on the ramp and runways?

Maybe the footage from runway cameras was sequestered for internal review.

I've watched nearly all the "Aviation Disasters" episodes. I don't recall any footage other than incidental amateur footage. The investigators spend a lot of time even figuring out where on the runway the various planes were, implying there was no footage.

Re: Why was there a wall near runway at S Korea plane crash airport?

#254

Post by SoftTalker »

dredmorbius wrote: post #215
mmooss wrote: post #89

Earlier quoted context omitted.

> it took them ~1.7 sec from leaving the tarmac until they hit the construction. If you measure the distance on Google earth you come up with ~140m. That means they hit the construction with roughly 296km/h or 160 knots. (Assuming the math is correct:) That's the average speed over that distance. The plane would have been slowing down the whole time.

Physics hack: The average velocity at constant deceleration is halfway between the initial and terminal velocities. So if we know the landing speed (which should come out of the flight data recorder), we'll know the terminal velocity given the average speed (distance/time) which is determinable from the video. No doubt Jeju 2216 was moving hot, but a longer run could have bled off far more speed, and kinetic energy i…

The plane was sliding on its belly, wheels up. It wasn't slowing down very much. Ever play on a slip-n-slide as a kid?

Re: Why was there a wall near runway at S Korea plane crash airport?

#255

Post by Xixi »

reso wrote: post #244
Xixi wrote: post #239

Earlier quoted context omitted.

You are making an assumption here, that I think is unreasonable: that the pilots (who have probably landed at this airport hundreds of times, it's not like they don't know the place) were expecting a large piece of reinforced concrete to be in the path of the plane. I'm speculating, of course, but pilots made the decision to land there (albeit in a very short amount of time). They probably made the reasonable assumpt…

You're making an assumption that the outcome would have been different if that wall wasn't there. You're wrong. 50m past that wall is another wall, 5m after that is a highway.

Indeed I'm making tons of assumptions, but you have not yet convinced me that they are wrong. A brick wall is no reinforced concrete, and how is a road at plane level fundamentally different from the runway the plane was "gliding" on?

Re: Why was there a wall near runway at S Korea plane crash airport?

#256

Post by neom »

WalterBright wrote: post #220
neom wrote: post #158

Earlier quoted context omitted.

It was in gound effect floating till very near the end, these two video show the story very well: https://x.com/vinfly4/status/1873285591900836307 https://www.reddit.com/r/aviation/comments/1hopl7d/longer_vi... As you can see, it actually isn't touching the ground for quite some time, it looks like it because one of the engines is smoking and the plane is throwing up dust etc from the ground as it floats above. Pure…

The reason he touched down halfway down the runway could have been because the gear was up. If the gear was down, he would have touched down much earlier. He may not have known the gear was up, or did not account for the gear being up in his approach.

They executed a pretty difficult turn, apparently it's called the impossible tear drop and you're trained specifically NOT to ever do it. I looked at the flight tracking, I suspect the maneuver they pulled just put them at that point in the runway[1]. If you read my reply to the comment above you, it has some additional context you might find interesting. They pilots I watched all mentioned really, it doesn't make sense they cut off the approach, they should have taken the bird strike and continued the landing. The probable reasons given was: took evasive maneuvers to avoid the brids so came off glide slope, not enough engine power for a full go around, then started to get way behind the plane.

[1]https://s.france24.com/media/display/579312a0-c8cb-11ef-81bd...

Re: Why was there a wall near runway at S Korea plane crash airport?

#257

Post by mannykannot »

reso wrote: post #149

The wall is a red herring. The plane landed halfway down the runway at high speed. Something bad is going to happen if you do that at any runway on earth. In SFO you'll end up in the bay or hit the terminal depending on the orientation. In Toronto you'll crash into a highway. Stop looking at the wall and look at the minutes before the crash.

This crash raises two separate questions: why did the airplane land the way it did, and did it make any sense to have a massive concrete barrier just off the end of the runway. The answer to either one does not render the other irrelevant. As it happens, we already know the answer to one of them.

Re: Why was there a wall near runway at S Korea plane crash airport?

#258

Post by Animats »

reso wrote: post #149

The wall is a red herring. The plane landed halfway down the runway at high speed. Something bad is going to happen if you do that at any runway on earth. In SFO you'll end up in the bay or hit the terminal depending on the orientation. In Toronto you'll crash into a highway. Stop looking at the wall and look at the minutes before the crash.

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...

Re: Why was there a wall near runway at S Korea plane crash airport?

#259

Post by scripturial »

FabHK wrote: post #235
timewizard wrote: post #226

Earlier quoted context omitted.

> The wall is a red herring. This is not how safety works. > Something bad is going to happen if you do that at any runway on earth. Then the question is can we do any sort of engineering to reduce the number of fatalities that might occur when this _inevitably_ happens. > Stop looking at the wall and look at the minutes before the crash. The plane hit the wall and exploded. The wall seems pretty important here. I me…

You could mandate that airports incorporate runways shaped as disks with 10 km diameter and another 5 km of empty space around them. Accidents would still happen.

Your suggestion is absurd and impractical. You’re not contributing anything useful. Of course accidents happen. Knowing accidents happen, People are asking why a large solid concrete structure is at the end of the runway. Especially given that it was known to be a bad idea.

Re: Why was there a wall near runway at S Korea plane crash airport?

#260

Post by sitkack »

likeabatterycar wrote: post #192
tooltalk wrote: post #184

Earlier quoted context omitted.

Occam's razor: the wall is most probably the cause of the unnecessary explosion that killed 179 people. The airport built ILS, or localizer, on unnecessarily over-engineered concrete structure where there shouldn't have been any obstruction. The ILS are supposed to be built on level surface or "frangile" structure so they can be easily destroyed when there is an overrun. There are reportedly at least 4 other airports…

[flagged]

You are disingenuously misrepresenting their argument. Please don't.
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