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

bbc.com

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

#171

Post by loeg »

gazchop wrote: post #51
K0balt wrote: post #39

Earlier quoted context omitted.

We don’t know why the pilot elected to double back instead of go around. There may have been indications of a progressive failure that indicated that course of action, but it does seem hasty. That haste may have caused them to not be able to set up a stabilized, minimum speed approach, and may have contributed to the long touchdown, which certainly was a contributing factor. If there were significant winds it would h…

They retracted the gear after the first landing attempt. I suspect they either missed it on the teardrop or had secondary hydraulic failure and no time to do a gravity drop. I would err on the side of crew error because there were clear signs the hydraulic systems were functioning (thrust reverser and that they could retract the gear in the first place). Hydraulics don’t fail instantly and one engine was spooling sti…

I've seen reports they had gear down in the first approach and also that they didn't. Is there anything conclusive yet?

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

#172

Post by loeg »

notimetorelax wrote: post #63
dredmorbius wrote: post #49

Earlier quoted context omitted.

This depends strongly on the airport, terrain, and variability of winds. There are airports in which approaches always or very nearly always follow the same profiles given local conditions. SFO, SJC, and SAN would be three examples off the top of my head. SFO's major approaches are over the bay, opposite approaches would involve rapid descents dictated by mountains near the airport. SJO and SAN are both limited by pr…

You’re right. Looking at the charts, it appears that both 01 and 19 can be used - https://aim.koca.go.kr/eaipPub/Package/2020-07-30/html/eAIP/... What’s noteworthy, there’s a note to use extreme caution due to this wall if landing or taking off towards it.

FYI, the 01 and 19 names are short for 10 and 190 degrees -- so it's always going to be the case that the opposite runway direction is 18 mod 36 from the other direction.

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

#173

Post by loeg »

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.

No one is discouraging investigation of the other factors or thinks they aren't significant.

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

#174

Post by est »

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.

You are missing the point. Runways are supposed to provide some room for errors. It's part of the investigation. You can't simply blame a human. Everything needs to be designed just in case

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

#175

Post by Affric »

MoreMoore wrote: post #161
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.

People keep saying that, but I don't see how it's excusable for there to be a massive concrete block against which planes disintegrate at the end of any runway. Maybe everybody would've died some other way, maybe only 10 people would have survived, who knows. But we won't know because somebody put a massive concrete block in the way. We aren't talking about any of your examples in this crash. And it isn't relevant fo…

Exactly.

Causality isn’t an equivalence relation with blame. A moral aspect has to be established.

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

#176

Post by loeg »

hu3 wrote: post #137
blueflow wrote: post #77

I'll recite an avherald comment: If you look at "Video of aircraft after touchdown sliding along the runway and impacting the fence:", you will find out that 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. If it wasn't the construction it would have…

160 knots? Google tells me: "Modern jets land between 120–150 kt. This depends on weight, weather conditions and several other factors." So even after scratching asphalt for 2/3 of the runway it was still faster than the normal landing speed. My uneducated gut feeling says pilot was trying to abort the landing.

Yes, it was a very fast landing.

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

#177

Post by loeg »

kristjansson wrote: post #167

The graphic in the article is pretty misleading. The video of the accident shows the plane touching down with about a third of the runway left, not two thirds. All discussion of the localizer obstruction is secondary to (a) why did they touch so late and (b) why did they land so urgently.

The figure I've seen is landing 1200m into a 2800m runway, which is about 1/3.

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

#178

Post by khuey »

loeg wrote: post #173
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.

No one is discouraging investigation of the other factors or thinks they aren't significant.

Except they are and they do. The quoted "air safety expert" in the BBC article essentially says the landing was "as good as can be" and that most or all of the people onboard would have survived if the localizer berm wasn't present.

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

#179

Post by loeg »

snypher wrote: post #135
foxglacier wrote: post #95

Earlier quoted context omitted.

> a few hundred meters would do nothing. I think the estimates I saw were over 150 knots Show you working. Not feelings because people don't have intuition for such unusual motion. You could equally have said "a few hundred meters would be enough."

150 knots is like 77 meters a second, a 747 can do like 2m/s^2 braking giving 35 seconds to stop, 1500 meters required. Stopping time: t=v/a, t=77/2. Stopping distance: d=v^2/2a, d=77^2/2*2

(That's with brakes and flaps.)

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

#180

Post by teleforce »

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.

To continue your idiom, it's not a red herring, it's the elephant in the room.

Seriously, I think the incident it's a hard lesson for airport designer and ICAO. For better civil aviation safety, the next airport runway should have ample room for safer aircraft landing without landing gears. Previously there's no real-time aircraft tracking requirement for passenger aircraft only for cargo, but after MH370 it's mandatory now and even ICAO acknowledged this very reason for the new regulations introduction.

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