Plane Crash in South Korea

[ericking]

Just two quick question for the couple of posters that have insight:

I've noticed that the entire runway/airport complex is surrounded by a brick wall with barbed wire on top. In the media and in here there has been some debate about the position of the mound that caused the plane to explode. But the brick wall is only about 30m beyond that so if the mound didn't exist the plane would have struck that at speed anyhow. Without knowing the physics of a passenger jet ploughing into a brick wall my guess is that that would have also caused the plane to explode too?

The other end of the runway has the same wall at a similar distance so the plane would have struck that too most likely.

So my main question is this: with the benefit of hindsight would a water landing have been a safer option?

 

[11101]

I've certainly heard the theories about an erroneous shutdown of the wrong engine, or an unfilmed second birdstrike in the other engine, leading to them only having one half-working right engine. Personally I find the video footage inconclusive whether or not the left engine is still delivering any thrust or if it was shutdown already during the landing. It does not have the reversers open, that's for sure, but that might also have been caused by them bellylanding on the nacelles.

But even without engines, I'd still say that it would have been a grave error not to deploy what they could when entering the final with obviously more than enough energy left to reach the runway. Their clean configuration resulted in them floating down the runway for ages, and with the gear out they could have plonked the aircraft down without so much care early on the runway, utilising its entire length. With flaps, they could have landed slower, needing less runway. Landing clean just seems like an overall bad decision if they had any choice to avoid that.

But the original bad decision to me was not following through with the initial approach. Sure, under normal circumstances it is always a good idea to go around if you feel something about your approach ain't right. You're not quite established right on the approach, you're getting windshear, you don't have sight before you hit minimums, whatever - just go around, try again, rather than force anything. But when you've just suffered engine damage and are losing power in one or both engines? And you're already all configured and lined up for the runway, on your final seconds of descending to the runway, and only a little over 2km away? Just go through with it, unless the approach was completely botched already. Nothing gets better from staying in the air longer with engine damage.

But really, I should just shut up and wait at least for the preliminary report.

There have been past cases where in the heat of the moment pilots have gotten confused as to the status of the landing gear, thinking it was down when it was not. Likewise with the flaps. Despite the aircraft blaring warnings they are sometimes missed.

Whatever went on it seems very likely pilot error was a contributing factor, but that is true of almost every accident.

 

[buchansleftleg]

A water landing is never going to be safer than an emergency landing onto a Runway.

The "Miracle on the Hudson" has given a false impression of the survivability of ditching a plane onto the water.

Water is way more "grabby" than a rubber coated tarmac surface.
Also if one engine is just a few centimetres lower than the other one it will be engulfed by water and spin the plane in a horrific twisting motion it is unlikely to survive.

Sully's skill in maintaining a very long glide to reduce speed and bringing the plane in absolutely level is incredibly tricky to do.

 

[hobbers]

I've noticed that the entire runway/airport complex is surrounded by a brick wall with barbed wire on top. In the media and in here there has been some debate about the position of the mound that caused the plane to explode. But the brick wall is only about 30m beyond that so if the mound didn't exist the plane would have struck that at speed anyhow. Without knowing the physics of a passenger jet ploughing into a brick wall my guess is that that would have also caused the plane to explode too?

The brick wall would have crumbled and done a fraction of the damage the reinforced concrete mound did. The plane might still have exploded, always that danger even without a barrier.

At the very least there would have been more plane left intact and more survivors than just 2.

 

[G3079]

Yeah, the "Miracle on the Hudson" is for once not called that for no reason. It really was a massive display of both skill and luck, and should not be mistaken for the normal result of an emergency water landing. And unlike a river in the middle of a metropolis with boats and helicopters abundant all around, landing somewhere in coastal waters with waves and rescue not just a few minutes away is upping the risk quite a bit, too.

Korean police forces have raided the airport, Jeju Air's company offices as well as the Busan Regional Office of Aviation today.
Not sure if they really have hints that something might be foul, or if it's just actionism, politicians and/or police wanting to display to the public that they are doing something instead of waiting around. Between this raid and the Boeing inspections in S.Korea it kind of feels like the latter to me. The police issued a statement that "The police plan to swiftly and rigorously determine the cause and responsibility for this accident in accordance with the law and principles." - which is plenty weird because air accident investigations aren't their job, it's that of the Aviation and Railway Accident Investigation Board in collaboration with external partners from the USA, Boeing as the manufacturer, the NTSB and the FAA. The acting president seems to display similar need to get uselessly involved rather than letting the actual professionals just do their jobs, ordering the inspection of all 737-800s operated by the country's airlines and issuing a statement: "As there's great public concern about the same aircraft model involved in the accident, the transport ministry and relevant organisations must conduct a thorough inspection of operation maintenance, education, and training,".
A good thing coming out of this is that they seem to have come off their initial defensive stance about the localiser construct used and are now putting the way those are built on their airports under reevaluation. Their first reaction after the crash and voices about the embankment being raised had been along the lines of it being a normal way to build a localiser that is similar to those of other airports in South Korea and worldwide.

 

[Enigma_87]

The speed the aircraft landed at was normal for a no-flaps landing. They had to come in that fast or they would risk a stall. That one is no mystery at all, it's a natural result of the aircraft configuration at the time. Depending on the landing weight you'll end up at around 200 knots with no flaps on a 737. The real question you want to ask is why it was in that configuration. Specifically, what was the state of its engines, hydraulics and electrics.

As for the emergency services, they simply did not have the time to prepare the runway. The aircraft reported the bird strike at 8:59m and touched down at 9:02 - not nearly enough time for them, if the pilots had even warned ATC that they had no landing gear, something I've not heard a report about yet. The emergency services most certainly were being alerted and getting ready to go, but they would not have been visible in the camera as standard procedure is to wait near the end of runway the aircraft is coming from and then following behind it after it touched down.

There was no correct or incorrect runway. The wind was almost calm and thus did not matter, and as for runway 01 not having an obstacle to crash into... that's not necessarily true. The northern end of the runway and the area beyond it is currently a construction area as they're working on a runway extension. I don't know the exact state of it during the incident, but there's every bit of a chance of there being heavy construction machinery, ditches, mounds of broken-up runway slabs or other material, and other obstacles present at the time. That part of the runway strip and the runway end safety area are specifically noted as being "unavailable" from September 18th to April 30th.
I also don't know if they had already removed the localiser antenna construction at the northern end, because that one's a construction similar to the south end - an earthen embankment with a thick concrete foundation inside and the antennas on top, the very same thing that absolutely shattered the aircraft at the other end of the runway. Maybe a bit lower, but every bit as devastating to an aircraft plowing into it at a hundred knots. Sadly the only video of the crash landing that really showed the northern end was not of a quality that let me see much, too far away and too blurry.

Yeah I'd imagine that was the reason for the approach, but still considering the length of the runway they had no chance of stopping at that speed. As you said the reason why they went with that configuration is key and which systems were in operation at the time. Bird strike taking the taking out the hydraulics would be really misfortunate and very rare occasion. Engines from what I see were working. Even with one engine it should be a protocol landing if other systems were in place.
Also not that familiar with Boeings but reversers activating without weight-on-wheels sensor is it possible, or this is only Airbus thing? 680's you can't deploy them unless you have the three WOW's are on the ground. On 320 it's when the mains are on the ground.

Going by the reports there was an initial failed attempt at landing (I'm assuming everything was ok in terms of configuration and systems were working as there wasn't a distress call), then they ascended again assuming systems were in check. The preflight check showed no issues as well.

Two minutes later the crew sent distress signal and attempted landing at the other runway (ATC gave them clearance), so yeah if they only had 3 minutes to prepare for emergency landing it wouldn't be enough, but that also probably means that the AC was in working condition before the distress signal and considering the first failed landing.

The bird strike isn't confirmed from what I read and a bird taking out hydraulics and electrics as I said is very uncommon and improbable. They happen way too often without losing the entire AC. Hydraulics are independent to engines so even if they did have engine issue that wouldn't have affected the other systems.

The northern part from what i saw was a field so you might be right about construction on site but probably gives them better chance even if the plane breaks apart on the way rather than smashing into the embankment.

CVR is processed from what I read and they are converting it into audio format so most likely investigators will have info pretty soon.

 

[Enigma_87]

So my main question is this: with the benefit of hindsight would a water landing have been a safer option?

Water landing is never a good option unless is favorable conditions and shallow waters.

There are couple of reasons landing on runway reduces the impact of landing by shock absorbing gear and tires. There is always the problem with flare. Landing on land you can more easily determine the height above the ground, whilst glass smooth water makes it harder to determine when to start the flare, if you are too high it's hard impact if it is too low you can dig the nose in.