Why was there a wall near runway at S Korea plane crash airport?
357 comments
·December 30, 2024reso
tooltalk
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 with such obstructions in South Korea -- at Yeosu, it's 4 meters high (also concrete foundation)[1].
<strikethrough>There was a similar accident in Hiroshima, Japan several years ago: Airbus A320-200 skidded past the end of the runway at similar speed and struck down ILS. It eventually stopped -- damaged the airplane but no fatality.</strikethrough>
1. Localizer at Yeosu Airport, similar to Muan's, raises safety concerns, 2025.01.02 (23:58), KBS News.
yongjik
> There was a similar accident in Hiroshima, Japan several years ago: Airbus A320-200 skidded past the end of the runway at similar speed and struck down ILS. It eventually stopped -- damaged the airplane but no fatality.
Are you talking about Asiana Airlines 162? It hit localizer on its way to the runway because it came in too low. It then hit the runway, skidded on the runway, and stopped about halfway (after veering off the runway at the last moment).
If the same thing happened in Muan, the plane would have hit the localizer and then touched down, stopping in the runway. The fact that the localizer's base was concrete wouldn't have mattered because that's not where the plane would hit it.
ricardobeat
If the wheels drop off my car at 100km/h and I lose control and hit a wall, is the wall the cause of the accident?
The barrier was 250m away from the end of the runway, the extra 50m if following regulations wouldn’t have changed the outcome. And if the wall wasn’t there, the plane would dive right into a highway anyway. That’s the point.
JohnKemeny
The wall is clearly not the cause of your accident, but might nevertheless be the cause of your death.
nialv7
bad analogy. a better one would be: a wheel fell of an F1 car, car hit perimeter wall, driver dies. should we maybe put a crash barrier in front of the wall?
broeng
Maybe that section of highway could easily be cleared in time with a warning system, like when we warn for crossing trains. A wall doesn't have to be the only solution.
dredmorbius
You might find AA 1420 (1999) of interest, similar situation though far fewer fatalities (11 of 145 souls):
<https://en.wikipedia.org/wiki/American_Airlines_Flight_1420>
Partially-effective runway braking and a much greater distance from runway perimeter to the nonfrangible ILS structure likely played a role.
inoffensivename
Are you talking about Asiana 162? https://en.m.wikipedia.org/wiki/Asiana_Airlines_Flight_162
That one touched down short of the runway at a much lower speed and configured for landing.
rmccue
> The ILS are supposed to be built on level surface or "frangile" structure
Nit: I think the word you want is “frangible”, easy to break.
likeabatterycar
[flagged]
dredmorbius
The pilots on 9/11 were intentionally directing their aircraft toward specific structures to maximise destruction, casualties, and terrorist impact. That was their express intent and mission for which they had specifically trained.
In all likelihood the pilot of Jeju 2216 was not specifically directing his aircraft to the nonfrangible ILS Muan Murder Wall. There is no way to charitably argue otherwise.
null
sitkack
You are disingenuously misrepresenting their argument. Please don't.
alkonaut
If it’s possible in any way to keep the next few km after a runway clear, then it should be clear. Ocean is great. Empty fields are great. If you are lucky enough to have empty fields but put a concrete wall there, then that’s almost malicious.
The cause of any fatality in aviation is never a single thing. It’s invariably a chain of events where removing any one thing in the chain would prevent the disaster.
sho_hn
Agreed. I work on a different type of vehicle with safety-critical systems for a living, and I'm naturally also very interested in the interactions between the pilots and the machine (and among themselves) and the spiral of events in the cockpit.
But that doesn't mean debating whether there's a better way to engineer typhoon-resilient localizer antenna arrays isn't also a good use of time. Safety makes it imperative to discuss all of these matters exhaustively.
Re ocean, no, that isn't so great - sea rescue is a lot more difficult to perform than on land.
alkonaut
Sure but if you have 3km of open water following the runway then don’t block it with a concrete wall (even if that wall prevents storm flooding 2 days every 5 years). Sea rescue is a lot easier than rescuing people who drove into a concrete wall.
blitzar
> If you are lucky enough to have empty fields but put a concrete wall there ...
I am fairly sure this will be one of the findings of the investigation. I hazard a guess that every sane operator of an airport in the world is walking from the end of their runway to the airfield perimeter and taking a look anyway.
imglorp
And if you don't have the space, there's also arresting systems you can install in case an aircraft runs long.
https://en.wikipedia.org/wiki/Engineered_materials_arrestor_...
m463
The wall might critical to keeping things off the runway, like animals and people.
dredmorbius
This one isn't. It's a relatively short support structure, not a battlement.
There are cinderblock a cinderblock wall and numerous chin-link (and razor-wire-topped) fences in the area, which do control airport access. Those would likely not have proved fatal to the aircraft to any similar extent however.
alkonaut
Those walls are there also on airports that do have open space beyond the runway. But they’re typically fences. Significantly cheaper and doesn’t disassemble and airliner upon impact.
Xixi
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 assumption that they could "safely" (as safe as it can be, of course) overshoot the runway in that direction. They were certainly not expecting to hit a concrete structure that would pulverize their plane.
Having large concrete structures near airports is not unreasonable, hiding them absolutely is. If instead of a hidden piece of concrete it had been a terminal like in SFO, a sea wall, or another known hazardous structure, the pilots could very well have decided to land somewhere else. Including in the very large body of water next to (or beyond) the runway.
You don't know, I don't know, and we might never know depending on what is uncovered by the investigation.
pixelesque
Firstly, this airport has only been taking international flights since the early December.
There was also construction work going on at one end of the runway (until March), and the threshold was pushed back 300 metres, shortening the runway by that much:
http://aim.koca.go.kr/eaipPub/Package/2024-10-31-AIRAC/html/...
The runway also is not flat (which is why the localiser beams at that end need to be raised in the first place to intercept the correct glideslope angle).
As the OP mentioned, trying this (a very fast landing, with no gear or flaps, spoilers) at many airports around the world on such a short runway (albeit one which with gear and flaps down is long enough for normal landings with the required 240 m runoff areas), is not going to work well.
Xixi
Very good point regarding international flights.
Of course, I'm making the assumption that the pilots somehow had to attempt a "a very fast landing, with no gear or flaps, spoilers". The core of the issue is probably there, hopefully the investigation will yield useful results.
But what I am fundamentally questioning is whether the pilots would have attempted that landing if they had been expecting a piece of reinforced concrete at the end of the runway.
To say it differently, it's not the existence of deadly obstacles near an airport that bothers me (after all, some runways are quite literally in the middle of cities), but the fact that the pilots could have reasonably not know about them. That, for me, is a pretty big issue.
There were plenty of concrete structures nearby when US Airways Flight 1549 ditched into the Hudson river: notice the pilot aimed for a path where there weren't any. Maybe that Jeju air pilot could have attempted something similar. Maybe not. But the absurd nature of that deadly piece of reinforced concrete probably didn't help making a good decision.
reso
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.
Xixi
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?
chii
the 2nd wall is a brick wall, rather than reinforced concrete (which is what seems to be the first wall).
I dont think the plane would get pulverized hitting a brick wall, and the distance will also slow the speed.
And the highway is not above the plane's travel axis, so the highway is a non sequitur. Not to mention even more distance to slow down.
inoffensivename
> 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.
Xixi
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.
Animats
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...
oefrha
> 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.
Animats
Oh, you're right. Different airport. Sorry.
Muan does have the chevron markings on the overrun area, but that does not always indicate EMAS.
stouset
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.
N19PEDL2
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.
teleforce
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.
reisse
No amount of ample room will help if the plane touches down overshooting more than half of the runway.
Furthermore (this is pure speculation at the moment) I think chances are the crew were kind of cosplaying PIA PK-8303 - forgot about landing gears in a stress from bird strike, attempted go-around after realising it, but had not enough power from engines due to bird strike or ground hit. It's plausible final investigation report will conclude absence of localizer antennas wouldn't save them.
dredmorbius
History says otherwise.
Most runway overruns occur with no or few fatalities:
gora_mohanty
People keep saying "half the runway", "more than half the runway" in this thread. The linked article has a large graphic saying the plane touched down about a third of the way down the runway.
mda
So survival chance of hitting a concrete wall and open field would be same?
I don't think so.
SR2Z
Very, very few airport runways are long enough for a plane without brakes to land halfway and be fine.
It's simply not possible to build airports in useful places and guarantee three-mile runways.
teleforce
Apparently runaway excursions is the third cause of major accidents of large commercial transport aircraft [1].
Muan airport runway distance is one the shortest in Korea, less than 3 km and ironically during the incident reportedly there is an ongoing construction to increase the length of the runaway to more than 3 km, but effectively further shorten the runaway to 2.5 km (similar to Yangyang Airport). Strangely South Korea has many shorter runway international airports.
Most of the modern international airport have more than 4 km runway, and new major airports for example Qatar Doha, US Denver and SA Upington has runaway length close to 5 km.
[1] Operational Landing Distances: A new standard for in-flight landing distance assessment.
[2] Muan Airport runway previously shortened, impact under scrutiny:
dredmorbius
You don't need the aircraft to survive.
You need the passengers to survive.
And that's eminently possible, even where the hull itself is destroyed (several cases of fuselages splitting in two or three with no or minimal fatalities):
Aloisius
> In SFO you'll end up in the bay or hit the terminal depending on the orientation.
The bay is survivable and I don't think you can hit the terminal. You could possibly hit the freeway though. That said, two of the runways at SFO are 1.5 km longer than the one in Korea.
> In Toronto you'll crash into a highway.
That runway is 1.5 kilometers longer than the one in Korea and it's another kilometer to the highway that sits uphill.
sinuhe69
I don’t think so. Would the localizer have been made of less rigid structure and not a steel-reinforced concrete, the fatality could be much lower. Also problematic is the brick wall at the end. They could make it as fence only and not a brick wall. That will help, too. Of course, one need to investigate the whole situation, for example why did the pilot choose to land immediately, why no flaps and spoilers were released and why no attempt has been made to manually release the landing gears (using gravity if needed) are things of intense scrutiny now.
YuukiRey
If you can get the same features with less risk it seems like a worthwhile thing to consider.
Meaning if we can build the same antenna array but with less risk to airplanes and all at an acceptable economical cost, it feels like something we should do. Regardless of whether or not a runway overrun at other airports and in other situations poses more or less risk.
blueflow
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 been the treeline or something else. That plane was doomed, concrete construction or not.mmooss
> 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.
dredmorbius
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 is based on velocity squared, so every bit helps a lot.
SoftTalker
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?
null
KallDrexx
It might not have been slowing down much in that time due to a thing called Ground Effect. Since the wheels weren't down, the flat body of the bottom of the aircraft + wings would have actually reduced drag and cushioned the plane for a bit, causing it to not slow down as much as you would assume.
formerly_proven
I'm not a pilot.
In the video it looked like the plane was only running on the rear landing gears, I assume with no brakes applied, since that would've caused it to violently pitch down I assume. Only in the last bit did it pitch down and started scraping along the runway. It certainly doesn't look like it was efficiently shedding speed (but looks can be deceiving).
krisoft
> In the video it looked like the plane was only running on the rear landing gears,
Are we talking about the same crash? In the video I have seen[1] the plane appears to be on its belly dragging on the runway.
dgfitz
I have been under the distinct impression for a long time that a plane slowing on the runway has very little to do with landing gear brakes.
loeg
Maybe. But maybe another 1000m of dirt would have been enough to slow them before the treeline. The area south of the runway is mostly an easement for the ILS approach equipment, then a parking lot and finally some trees.
It's also definitely the case that the cement-reinforced dirt mound is not best practice for a locator array.
TylerE
Yes, but in basically every single circumstance if you have room for 1000m of dirt, you have room for another 1000m of runway, which is even safer.
bombcar
This is the reality - most airports run their runways “to the fence” for some variation of “to the fence”. If they could reasonably have a thousand extra feet of runway they’ll add that, as it supports more operations and doesn’t really hurt.
Some of them even move around the recommended touchdown point depending on other factors, if the runway is extra long.
MoreMoore
So you'd rather them have a certain 100% chance of death instead of more leeway and a chance against much less robust trees? Honestly, if I crash land, I think I prefer 150 more meters and a tree as the obstacle over the concrete block.
What is going on here and what's with this crazy ass logic?
blueflow
Do you believe the plane would have stayed in one piece if it wasn't for obstacles?
hypeatei
> What is going on here and what's with this crazy ass logic?
Nothing is crazy about it. Many people in this thread (like you) are in a tizzy over a concrete wall for a plane landing with no gear at high speeds. Your argument is basically "having no wall would make me feel better" which has no logic and very obtuse.
The ground is also a hard obstacle and this plane would've hit uneven ground shortly after the runway regardless. It's going to disintegrate either way.
null
hu3
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.
sio8ohPi
Normally they land with flaps down, which reduces landing speed.
05
I've heard sometimes landing gear is also involved..
We really need a placebo controlled double blind study to learn if landing gear is actually effective of just a cargo cult like parachutes.. [0] https://www.bmj.com/content/363/bmj.k5094
mianos
There were no flaps deployed. Without flaps it's going to be a lot faster than a normal landing.
loeg
Yes, it was a very fast landing.
drdrey
just because that aircraft was doomed (maybe?), that doesn't make it a good idea to have the concrete wall there
inoffensivename
Lots of airports have obstacles not far from the end of the runway. Burbank, Midway, Orange County are a few that come to mind.
Why did they need to land when they did?
Why did they need to land so soon after the mayday call? (only 8 minutes from mayday to crash, as I understand it)
Why couldn't they land on a longer runway?
Why did they land so far down the runway?
What forced them to land in a clean configuration?
As an airline pilot, these are some of the questions I have. The flight data and cockpit voice recorders should be able to answer these questions.
cameronh90
The obstacle obviously didn't cause the crash, but it's still probable that fewer people would have died if it wasn't there, and it seems to have been put there for no valid reason, quite recently, and against standard practice. Along with the reports that their bird control devices had not been implemented and that only 1 of the required 4 staff to repel birds were on duty. All these factors together may suggest an issue with their safety culture.
Though, I am a little sceptical of the claims that it would have hugely reduced fatalities either way. Runway excursions into unmanaged terrain at that speed don't usually work out well for the passengers, even when the terrain appears relatively flat.
I'm not an airline pilot, but I'm still curious to see what caused such an unusual crash, since there doesn't seem to be any single issue that could have caused what happened. So far, my best uninformed guess is a combination of pilot error and bad luck: the approach wasn't stabilised, so they started executing a go-around, and THEN a multiple bird strike caused catastrophic damage to the right engine. This may have led to smoke in the cabin/cockpit which they interpreted as a fire (or some other issue, vibrations etc.) that made them decide to shut down the engine, but they shut down the wrong (left) engine. So now they think they have a dual engine failure. At this stage they obviously don't have time to run through paper procedures, and they put the plane into clean configuration to maximise glide and attempt a 180 to try and land back on the runway. Then they either couldn't or forgot to deploy the gear, and floated down the runway partly due to ground effect from being at an unusually high speed, thus landing at high speed almost halfway down the runway. Thoughts?
tolciho
"Normal Accidents" is a term for when things, well, normally go sideways in complex systems, and there's a whole book on it. Otherwise, it's pretty typical in disasters for there to be a laundry list of root causes and contributing factors: the Titanic was going too fast, there was hubris, and icebergs, and it was sad when the great boat went down. Could the disaster have been missed or been less bad if one or several factors had rolled up some other result? Maybe! That's what a full investigation is for, to suss out what went wrong and what things are most fixable.
dredmorbius
A favourite! By Charles Perrow (1925-2019).
ak217
I don't know why the pilots landed the way they did but the structure was there for a valid reason. It's the runway localizer antenna. It was elevated off the ground to protect it from flooding. Should it have been frangible, yes, but it's not at all out of the ordinary as far as structures near runways go, and I think the focus on it is sensationalist and misguided.
cameronh90
By structure I meant the dirt mound with a concrete wall inside it, not the localizer. Entirely normal to have a localizer, but usually on a frangible structure if it needs to be elevated.
jmward01
These were my thoughts exactly. Even if they lost all engines/power/hydraulics they would have had 8 mins to start up the APU so gear and flaps wouldn't have been an issue and clearly they still had some control. Did they try to go around and lose all power on the go? Gear up landings do happen in GA but I can't think of the last commercial aviation gear up landing. There will probably be a lot of useful things coming out of this. Changing design and placement of structures at the end of runways probably isn't a big one though.
pfannkuchen
Were those obstacles installed by the airport though? I thought it was like stuff on land outside of the airport for those other examples.
dmurray
Does it matter? Either it's safe to have obstacles within 300m of the end of the runway, and this was a reasonable location for the Korean airport to put their localizer in, or it's not, and the likes of Burbank should shorten their runway to ensure there's sufficient buffer space at the end of it.
brookst
I’m suspicious of decontextualization in the name of forming “either X or Y” absolutes.
Either 8 character passwords are fine and secure, or bad and should be banned? With no context between “€x8;,O{w” and “password”?
I suspect runway design has more variables than just distance to obstacles.
hmcq6
>and the likes of Burbank should shorten their runway to ensure there's sufficient buffer space at the end of it.
... you can't be serious with this? 300 more feet of unused runway is equivalent to if not better than 300 feet of buffer. You're fixated on following the "rules" without any understanding as to why they exist.
iso8859-1
The localizer antenna mount (the concrete) was inside the airport perimeter. See diagram:
https://multimedia.scmp.com/embeds/2024/world/skorea-crash/i...
sho_hn
The OP knows this already.
What they were saying is that just because other airports feature runways situated next to natural obstacles and this is allowed and equally dangerous, it doesn't mean this airport needed to have this particular, deliberately designed and implemented obstacle next to the runway.
The reason for the concrete-reinforced berm was typhoon resilience. It begs the question whether there are alternative designs that are trade of requirements better.
darkhorn
Nice questions. But it doesn't give them right to build a concrete obstacle for lights, when it is possible to make it without hard obstacle.
aaron695
[dead]
neom
My wife is South Korean (from andong). I asked her and she looked at me like I'd grown a second head "because it's South Korea? We're a young country and that is tiny airport in the south, half of Korea is a safety hazard and you know that fine well, some freaking idiot put a wall there, oh well, it's korea" and walked off pretty angry I'd even asked.
bombcar
To be fair to her, check out some of the other things that have happened.
Compared to that mall collapse, a berm that far off the end of the runway won’t even be notable.
neom
Oh I'm fully aware, I take no issue with her ire, just didn't expect that answer, tho I should have. To her point, the South of South Korea, especially in the country area, has loads of stuff like this, there are disasters waiting to happen everywhere, much of the infrastructure should be gone through with a fine tooth comb really, like this still both boggles my mind and boils my blood: https://www.reuters.com/world/asia-pacific/fire-south-korean...
They used a HIGHLY flammable material to completely cover a raised highway.
(All of that said, I read from so many people now that the plane would have disintegrated once it did finally start to drag given the speed, and there is another parameter wall shortly after the berm.)
boodleboodle
Safety hazards and disregard for accesibility as well
null
carabiner
[flagged]
dang
Personal attacks will get you banned here—and this was a shameful one. No more of this, please.
Edit: we've had to ask you many times to stop breaking the site guidelines:
https://news.ycombinator.com/item?id=38198402 (Nov 2023)
https://news.ycombinator.com/item?id=37367901 (Sept 2023)
https://news.ycombinator.com/item?id=36896498 (July 2023)
https://news.ycombinator.com/item?id=35759087 (April 2023)
https://news.ycombinator.com/item?id=34698866 (Feb 2023)
https://news.ycombinator.com/item?id=25128446 (Nov 2020)
Eventually we have to ban accounts that keep doing this, so please stop.
null
fontrash
What the hell.
iso8859-1
[flagged]
neom
"One strategy I use for my relationships with foreigners is to gently pat them on their heads if they understand me. That way, there is positive reinforcement and they are encouraged to improve their understanding." - this may very well be one of the most condescending and disrespectful things I've read on hackernews ever. Also, my wife has a PhD in American History from Yale and teaches at SUNY, I don't suspect she misunderstood the question.
iso8859-1
You're assessment is correct and it was indecent of me to say such things. I'd like to apologize for both the condescension and the lack of respect.
shutupnerd0000
[flagged]
dralley
>Tell her she is wrong. It's an international airport with commercial traffic. 11th most busiest airport in the country.[0]
11th out of 15 total, servicing about 4 flights / 630 passengers per day on average using the very same statistics you've linked. That sounds like a pretty small airport to me, both in absolute and relative terms.
"International airport" means very little outside of large nations like the US, Russia, Canada, Brazil or China. Most nations are small enough that there's at least as many foreign airports within a few hundred kilometers as there are domestic ones, and therefore every airport may as well be an international airport.
mikestew
"International airport" means very little outside of large nations like the US, Russia, Canada, Brazil or China.
In the U. S., at least, "international" just means there's a customs station. There are some pretty small airports that have "international" in the name. Fairbanks, Alaska, comes to mind.
iso8859-1
That's a great observation about 'international airport'. There is no point in mincing words regarding the definition of 'tiny'. I think you've correctly characterized the size of the airport.
frosting1337
> Tell her she is wrong. It's an international airport with commercial traffic. 11th most busiest airport in the country.
It's... a tiny airport, both by commercial standards and by South Korean standards.
Pretty sure you're just trolling though, no way this is a serious comment.
mcflubbins
I was wondering the same thing and suspected it was some safety feature (better for a plane to smack into said wall instead of crash into some populated area, etc) I had no idea he had to make the approach in the opposite direction.
gazchop
They already botched a gear down landing, which is almost never mentioned. They retracted the gear and did a teardrop go around from a headwind into a tailwind belly flop.
Stinks of bad crew resource management and ATC which is why the ATC and airline for raided by SK officials.
K0balt
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 have compounded those factors.
It is curious that the gear was retracted. I can only think that this was due to some kind of system failure? Perhaps that same failure explains the decision to double back instead of going around?
Lots of questions, hopefully there will be answers.
Still, the structure does not seem to meet the standard for frangibility that is indicated for objects in the approach path within 300m, although it’s not like it was at the very end of the runway.
Runway over/undershoots are actually quite common, and the building of a nonfrangible structure on an otherwise safe skid zone is a significant error in design principles that is not common or conformal to industry standards.
If those antennas had been placed on property designed towers instead of a concrete bunker, the passengers and crew very well may have walked away without a scratch, despite any errors on the part of the crew or procedures of the airline.
loeg
They declared mayday and then were on the ground in like 3 minutes. I think they probably just forgot gear given how rushed the landing was. We'll find out from the investigation.
gazchop
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 still on landing.
That's why EASA says put the plane down if there’s a strike on approach. Ryanair 4102 is a good example of a close one there as a reference.
null
fl7305
What should ATC have done differently?
K0balt
lol.
People often have an idea that ATC actually controls what happens. They just give advisory guidance to pilots, who ultimately decide what to do. A clearance to land or the lack of one does not absolve the pilots from making their own judgments and decisions about how to conduct the navigation of the aircraft, and where and when to land.
Usually, it’s a bad idea to not follow ATC guidance, but in the case of emergencies especially, pilots call the shots.
gazchop
Possible comms failure. ATC are responsible for reporting surface wind. It may have lead to a bad decision by the pilots. Go around versus teardrop etc.
whycome
Botched how?
mianos
Botched by not using the manual gravity gear drop. Maybe they didn't have enough time. But losing a single engine is not necessarily fatal at that flight phase. Most professionals are still questioning why the rush to get it down. If there is some valid reason, aside from accidentally shutting down the other engine, when we do find out the details, maybe the professionals won't call it botched.
aaron695
[dead]
Towaway69
This:
> no idea he had to make the approach in the opposite direction.
So the wall is actually at the beginning of the runway. That wall was never never meant to be at the end of a landing but at the start of landing.
I don't understand why this isn't made clear. Basically the runway was used against the design specifications.
ra
That's not correct. A runway can be used in either direction, if you look on Google maps you can see the runway at Jeju has markings at both ends including a number (denoting it's compass heading) - both ends are usable.
You always want to land with a headwind and never a tailwind, so ATC will use whichever end is favorable for the current conditions.
In this case, if they attempted to land with a tailwind then the on-heading vector component of wind velocity must be added to the airspeed to get the ground speed... whilst this was a contributing factor to the accident, it's not something to focus on.
There will be a thorough investigation but it will take some time to get answers.
rich_sasha
I read that the opposite direction had a NOTAM exclusion, i.e. was excluded from use. From the professional pilot forum linked a few days ago in a similar thread.
If that's right then OP would be correct in saying, this direction wasn't meant to be used.
kgwgk
> if you look on Google maps you can see the runway at Jeju
Do you mean at Muan?
Towaway69
Thanks for the clarification :+1:
It should perhaps be pointed in news coverage since I equated "opposite direction" with "wrong direction" - hence my scepticisms about the wall.
K0balt
Idk about this particular airport but it is nearly universal that runways are used from both ends. The idea is to land into the wind.
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.
Still, a 14 ft high concrete structure within 300M of a runway end is unusual, and does not fit the standard for frangable structures which is the guidance for runway aligned equipment.
null
weweersdfsd
Even if the runway was only used from one direction (not true), it would be dumb to build a big concrete structure near its beginning. It's not unheard of for planes to come in too low and touch down before start of the runway due to pilot error (or even double engine failure on rare occasions).
ajmurmann
Was the runway designed to only be used one way or was this just the it opposite direction of how it was being used at that moment? I understand that at least some airports change the direction based on wind.
notimetorelax
Runways are approached from both ends depending on the wind.
dredmorbius
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 proximate downtowns with tall towers. Nominal approach glide paths cut below the rooflines of several structures, and make for some interesting experiences for arriving travellers.
lutusp
> So the wall is actually at the beginning of the runway. That wall was never never meant to be at the end of a landing but at the start of landing.
Airports like this are designed to have two approach directions -- in this case, 10 and 190 degrees. Either approach direction would have been acceptable depending on the prevailing wind.
null
null
kelsolaar
Ate Chuet made a quick analysis about the crash: https://youtu.be/xUllPqirRTI. The wall is there because that area is regularly flooded, it serves for the ILS system, and it is unfortunately over the minimum legal distance for such an object.
harshreality
It doesn't make sense, though, that it would have to be concrete-reinforced above ground, and non-frangible, just because the area floods.
Maybe it's the cheapest way to engineer the ILS localizer to be flood-resistant? I don't know.
psychoslave
Just a message thinking for anyone reading who might have had some relative in this plane: sincere condolences.
dominicrose
A plane usually crashes because of multiple reasons. The fact that runway design was one of them is a big deal because it was a concern for all airplanes landing there not just one of them.
justinl33
The wall is a red herring 2. why was a commercial airliner attempting a no-gear belly landing with full fuel load on a runway that's only 2,800m, rather than divert to Incheon?
ropable
This is probably only the tenth or eleventh most-important question to answer about why this disaster happened, unfortunately.
kristjansson
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.
loeg
The figure I've seen is landing 1200m into a 2800m runway, which is about 1/3.
kristjansson
In the longer video, there's clear sparks from the tail strike when the plane is in line with the northeast-most structure of the airport. Lining that up with the camera location shows almost exactly 1200m of runway _remaining_.
baq
The title question is like the 20th in order of importance why this crash happened…
null
blitzar
Cause of death was impacting a concrete barrier.
ynniv
Cause of death was landing halfway down a runway at high speed with no gear. Why were they cleared to land if they hadn't set flaps and locked gear? There was ocean in front of them both before and after their turn: landing there would have been more survivable than landing fast and hard with no gear. They were below minimum turnback altitude, and wouldn't have been able to complete the planned turn without the same power that could have been used to stay aloft and sort out their problems.
Nothing about this crash was normal, and talking about a thing past the end of the runway is misdirection.
bink
They declared an emergency. It's typical in that scenario to be approved for whatever runway the pilot deems best... or golf course... or field.
blitzar
If we go back far enough the fatal error is the Wright brothers inventing the airplane.
It might be more useful to start with the solid concrete plane stopper and work backwards than work forwards from 1903.
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.