[HN Gopher] Why was there a wall near runway at S Korea plane cr...
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Why was there a wall near runway at S Korea plane crash airport?
Author : vinni2
Score : 55 points
Date : 2024-12-30 18:22 UTC (6 days ago)
(HTM) web link (www.bbc.com)
(TXT) w3m dump (www.bbc.com)
| hilux wrote:
| So many things went wrong, and yet the pilots brought the plane
| down safely - and then this!? Just infuriating.
| underseacables wrote:
| They did not bring the plane down safely! The pilot failed to
| lower the landing gear, or extend the flaps, both of which, for
| all intensive purposes were technologically possible. Multiple
| redundant systems for these. I think they completely lost
| situational awareness, and panicked.
| K0balt wrote:
| When an engine blows up, it's hard to say what still worked
| and what didn't. They aren't supposed to, but when turbines
| come apart, there is often a lot of shrapnel that has a
| history of taking out multiple systems.
|
| But, it is possible that it was a case of poor crew
| performance.
|
| In any case, the concrete blockhouse at the end of the runway
| was unhelpful, and it is also outside of the standard
| guidance for runway aligned obstructions. In most cases,
| those antennas would have been on frangible towers, and the
| crew, at fault or not, as well as the passengers, would have
| had a decent chance of walking away unharmed.
| f1shy wrote:
| There are 3 different hydraulic system plus one electric
| that can be operated out of a battery... anything is
| possible, but it seems until now they failed to lower the
| gear.
| underseacables wrote:
| Something else that may be a factor, a lot of Asian
| carriers teach their pilots to use auto pilot for
| landing. American pilots almost universally SOP do not
| use auto pilot when landing. It's possible the South
| Korean pilot was using auto pilot to land, forced to do a
| go around, but wasn't in the habit of manually
| configuring the plane for landing. That's how the flaps
| and the gear were both missed. He assumed autopilot etc
| was handling that.
|
| I think in the cockpit voice recording we are going to be
| hearing the sirens going off about no landing gear and
| those guys were just not paying attention.
| K0balt wrote:
| That would be a tragic void in training and procedure. I
| hope for the sake of the families involved that it
| doesn't turn out to be something so avoidable in practice
| and foreseeable in the carriers operating procedure.
| f1shy wrote:
| I'm afraid it will be something like that...
| wat10000 wrote:
| There are numerous past examples of this sort of thing.
| Automation in aviation is really hard to get right. If
| the automation can fail then the pilots need to be able
| to perform whatever it was going to do. If the automation
| fails rarely then the pilots may not get enough practice.
| But if the automation normally does a better job than the
| pilots, there's a tension with letting them get more
| practice on real flights.
|
| A recent(ish) example is the Asiana crash in SF. They had
| pretty much perfect conditions for a hand-flown visual
| approach, but they were out of practice, got behind the
| airplane, and it snowballed.
|
| There's an excellent lecture about this called Children
| of the Magenta Line. The magenta line being the flight
| path or direction indicator on an autopilot, and the
| discussion is about pilots who constantly reconfigure the
| autopilot to direct the plane instead of just taking
| over. https://youtu.be/5ESJH1NLMLs
| robinson-wall wrote:
| Which aircraft have flaps or gear controlled by an
| autopilot? I'm just an armchair "Air Crash
| Investigations" fan, but I've never heard of any aircraft
| where either flaps and gear would be automatically
| controlled by their autopilot. Speedbreaks / spoilers are
| usually armed and moved automatically on landing.
| loeg wrote:
| There's also a backup manual gear release. But from the
| degree of control over the airplane demonstrated during
| landing, it seems likely they had hydraulics.
| f1shy wrote:
| They were with gear down, the retracted it, as part of the go
| around...
| kiririn wrote:
| >for all intensive purposes
|
| Always a funny one, it's for all intents and purposes
| f1shy wrote:
| Absolutely no. There is the suspicion that they even shut down
| the good engine after the bird strike.
| wat10000 wrote:
| Bringing a plane down safely involves doing it in a way that
| lets you come to a stop before you crash into something that's
| going to kill everyone. You don't get points for touching a
| runway at a point where there isn't enough of it left for you.
|
| No commentary on the pilots' role here, we don't know nearly
| enough to judge. Could be they did a great job and they were
| just doomed. But the end result is that they didn't get it down
| safely.
| mcflubbins wrote:
| 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.
| Towaway69 wrote:
| 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.
| notimetorelax wrote:
| Runways are approached from both ends depending on the wind.
| dredmorbius wrote:
| 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.
| notimetorelax wrote:
| You're right. Looking at the charts, it appears that both
| 01 and 19 can be used - https://aim.koca.go.kr/eaipPub/Pa
| ckage/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.
| ra wrote:
| 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.
| Towaway69 wrote:
| 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.
| rich_sasha wrote:
| 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.
| loeg wrote:
| Ok but in an emergency all bets are off, the opposite
| direction is better than a crash landing. So you can't
| just assume 100% of landings are in one direction.
| K0balt wrote:
| 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.
| ajmurmann wrote:
| 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.
| weweersdfsd wrote:
| 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).
| lutusp wrote:
| > 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.
| gazchop wrote:
| 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.
| fl7305 wrote:
| What should ATC have done differently?
| K0balt wrote:
| 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 wrote:
| 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.
| K0balt wrote:
| 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.
| gazchop wrote:
| 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.
| loeg wrote:
| 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.
| Mistletoe wrote:
| I don't know why people keep fixating on this. Airplanes can't
| skid out of the airport into the surrounding city. Mistakes were
| made, but this isn't one of them. I suspect it is people trying
| to deflect blame from pilot error, which seems by far the most
| likely issue. They did none of the things you should do to stop a
| plane.
| looseyesterday wrote:
| You are probably right on pilot error, dont forget Boeing
| probably want this to be the story as well!
| cenamus wrote:
| But it wasn't there for this reason, and if it was, I'm sure
| they would have had more than 250m of space to put it at the
| far ends of the airport.
| cm2187 wrote:
| Like doing what things? What I read so far is that they suspect
| the pilot had control issues.
|
| I don't think people who say that it's a bad idea to have a
| concrete wall at the end of the runway argue the plane should
| make its way to a nearby motorway. I think most refer to using
| EMAS, ie a crushable concrete floor in which the plane sinks
| and stops.
| Towaway69 wrote:
| > bad idea to have a concrete wall at the end of the runway
|
| but was it the _end_ of the runway? As I understand, the
| pilot came in from the opposite direction, i.e.
|
| > The pilot then aborted the original landing and requested
| permission to land from the opposite direction.[1]
|
| So that wall was located at the beginning of the runway _if_
| the runway was used correctly.
|
| From the bottom image[2], it would appear the wall is located
| behind the point where planes begin their take-off (and I
| assume their landing) - but I'm no aviation expert.
|
| [1]: https://www.bbc.com/news/articles/ckgzprprlyeo [2]: http
| s://ichef.bbci.co.uk/news/1536/cpsprodpb/9090/live/ab9db...
| fl7305 wrote:
| > So that wall was located at the beginning of the runway
| if the runway was used correctly.
|
| Most runways are intended to be used in both directions
| depending on the wind. This one doesn't seem to be an
| exception?
| Towaway69 wrote:
| Yep mea culpa, I now understand a little more about
| aviation!
| HPsquared wrote:
| Looking at the map, there isn't much beyond the runway.
| csomar wrote:
| There is nothing beyond the embankment. Airports are generally
| made in the middle of nowhere. And no, they are not "skidding"
| into the surrounding city, he probably needed a few hundred
| meters at most.
| Mistletoe wrote:
| He's going extremely fast, a few hundred meters would do
| nothing. I think the estimates I saw were over 150 knots.
| That's about 77 meters per second.
|
| I found this comment helpful from a Reddit thread.
|
| >The embankment is there to protect the road from the
| jetblast of departing aircraft in oposite runway direction.
| Thats why it is allowed directly in the safety area.
| psychoslave wrote:
| Maybe not all completely aligned straight forward with the
| landing, but it looks like yes there are some inhabited zones
| over there surrounded by wooded parcels, well before the
| landscape change for some sea.
|
| https://maps.app.goo.gl/BN15aSQ1pW6vJkzb7
| csomar wrote:
| 740m before hitting the next structure.
| gazchop wrote:
| I think this is disingenuous reporting.
|
| It's too early to actually draw a conclusion. We should wait for
| the full investigation.
|
| There are a large number of compounding problems here. That was
| just the last one.
| copperx wrote:
| Even with all of the compounded problems, the flight could have
| been non fatal in most world airports.
| gazchop wrote:
| I wouldn't state that with any certainty. They touched down
| 1500m down the runway with little to no braking or reverse
| thrust. The ending may have been less violent but the outcome
| may have been the same. I'd rather go from blunt force than
| being burned alive if a wing ditched and it rolled.
|
| Let's wait for the investigators. It's not good to fixate on
| this outcome.
| ckw wrote:
| This is the landing of United Airlines Flight 232 in Sioux
| City, Iowa in 1989. It hit the runway very hard, tumbled,
| broke, left the runway, and burned, but encountered no
| significant non-frangible obstacle. Of 296 passengers and
| crew on board, 184 (62%) survived. It is reasonable to
| assume that given the absence of other significant non-
| frangible obstacles beyond the ILS mound that loss of life
| would have been low and potentially zero.
|
| https://youtu.be/sWkU6HRcOY0
| thekevan wrote:
| "... the significance of the concrete wall's location about
| 250m (820ft) off the end of the runway."
|
| "...the runway design "absolutely (did) not" meet industry best
| practices, which preclude any hard structure within at least
| 300m (984ft) of the end of the runway."
|
| "it emerged that remarks in Muan International Airport's
| operating manual, uploaded early in 2024, said the concrete
| embankment was too close to the end of the runway."
|
| I mean that was a pretty obvious design flaw that went against
| common standards. I agree it isn't cut and dry yet but an
| investigation isn't going to change the above info.
| gazchop wrote:
| I don't disagree with that. It is a compounding issue but I
| am much more interested in what happened up to that point.
| Many many small things or one big thing went wrong for it to
| even get to that point.
| thekevan wrote:
| But don't forget, that point you mention is the point where
| the people were killed.
| gazchop wrote:
| There is a whole chain of causality. They were killed by
| multiple successive problems compounding.
|
| See Swiss cheese model.
| thekevan wrote:
| I'm really not sure the chain of bird strike, belly
| landing, mid runway landing and fiery explosion are equal
| parts of that chain. One seems to weigh heavier than the
| rest.
| gazchop wrote:
| There's a few more you're missing there which is the
| point of the investigation.
| rich_sasha wrote:
| So it would appear that this structure would be fully
| compliant if placed 50m further. That's less than a second's
| difference. The plane would crash into it at the same speed,
| just a tiny bit later.
|
| OP is 100% right that many, many things must have gone wrong
| for the position of this structure to remotely matter (human
| or mechanical errors).
| tedunangst wrote:
| How much difference would an additional 50m have made?
| baq wrote:
| To be brutally honest, the plane would crash about a second
| later, so approximately none whatsoever.
|
| But this isn't the right question to ask, as it isn't the right
| question to ask why the wall was there. Why did the pilot and
| ATC decide it's a good idea to attempt a gear up landing in the
| wrong direction is a good start.
| EliRivers wrote:
| I recall back in 2020, when Pakistan International flight
| 8303 belly landed at Karachi, slid down the runway, and then
| took off again and had a go at going around, the
| investigation showed that between them, the pilots just
| screwed up on having the landing gear down and had a go at
| landing without it for no other reason than they fumbled it.
| loeg wrote:
| The PIA pilots totally fucked up the approach, missed that
| they were very high late in the approach, dive bombed down
| to the runway at the last minute instead of going around.
| CRM issues -- the senior pilot plausibly couldn't actually
| fly (he had a history of bad approaches with unsafe
| descents) and the first officer failed to raise major
| problems or push back at all on unsafe decisions. When they
| first touched down gear up, they had dual stick inputs (one
| pilot was pushing down, one was pulling up) -- this is a
| huge no no. Communication in the cockpit was awful. Just
| lots of awful.
|
| After the incident, PIA pilots were audited and determined
| like 1/3 had fake or suspicious pilot licenses(!!!). Lots
| of paying other people to pass tests for you.
| Internationally, PIA has been banned from landing by like
| all first world countries.
| __m wrote:
| Compared to running into a concrete wall probably a lot
| SideburnsOfDoom wrote:
| 50m of runway? Not much difference
|
| 50m of arrestor bed? Some difference, probably meaningful.
|
| https://en.wikipedia.org/wiki/Arrestor_bed
| loeg wrote:
| They'd probably have another 1000m of relatively clear ground
| without the localizer mound. The brick fence probably wouldn't
| significantly slow the aircraft, then you have a relatively
| clear easement (with ILS approach towers, hopefully frangible)
| until a parking lot and trees on the south coast.
| baq wrote:
| The title question is like the 20th in order of importance why
| this crash happened...
| Jabrov wrote:
| Runway's gotta end somewhere
| vasco wrote:
| Technically it could loop around the earth.
| echoangle wrote:
| You don't even have to make it that long, you can just make a
| large circle of runway:
|
| https://en.wikipedia.org/wiki/Endless_runway
| ge96 wrote:
| I was wondering what if they tried to turn whether by rudder or
| thrust differential would the outcome have been different/worse.
| Maybe you can't do much at that speed and so little room.
| lutusp wrote:
| I'm a pilot. The airplane was sliding on the ground and the
| landing gear was not deployed. Too fast to stop but not fast
| enough to use the rudder for directional control. There was no
| realistic chance to change direction.
|
| If there had been enough engine power to control direction on
| the ground, there might also have been enough power to remain
| airborne, but based on limited information, that wasn't so.
| Under the circumstances the pilots would have wanted to stay
| airborne to buy time for a more controlled descent, were that
| possible.
|
| All these speculations are preliminary and may completely
| change once the black box information is released.
| rogerrogerr wrote:
| > not fast enough to use the rudder for directional control.
|
| Sure about that? 160kt (how fast someone calculated it went
| off the end of the runway) is way above Vs1 for a 737, there
| should be plenty of rudder authority. Heck, Vapp is usually
| in the 130-150kt range.
| gsf_emergency wrote:
| Korean police have raided the airport offices
|
| https://youtu.be/3D9BDIH553U
| psychoslave wrote:
| Just a message thinking for anyone reading who might have had
| some relative in this plane: sincere condolences.
| Yeul wrote:
| I have been to airports whose runway end in the ocean, a swamp, a
| mountain and a 5 lane highway.
| dominicrose wrote:
| 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.
| kelsolaar wrote:
| 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.
| blueflow wrote:
| 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.
| loeg wrote:
| 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.
| mmooss wrote:
| > 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.
| formerly_proven wrote:
| 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).
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