Jeju Air 737 Crash

My heart goes out to the families of the passengers and crew who’s lives were lost. The airline’s employees also have my deepest sympathies. For the next year and beyond, they will question everything about an operation that 24 hours ago was a source of deep pride.

I flew the 737 for 20 years. Most of that time was in the -800, the type destroyed in the tragedy yesterday. We, mainly me, have opined to the tune of thousands of words about the Max crashes and the debacle that Boeing has become. But the airplane is a great one. What makes it great is its utter simplicity. Other airliners become lawn darts when hydraulic pressure is lost. The 737 remains perfectly controllable through cables, servos and (maybe?) anti-servos. Much of the technology that resides inside a new Max as it rolls out of the factory is unchanged from the first 737 in 1964. I write this to set up what has me so baffled by the accident. Here’s what we know at this early hour while crews are still searching for survivors:

A video I’ll not post here shows the airplane landing smoothly with none of the gear extended. It barely decelerates before exiting the right edge of the runway and immediately striking a concrete wall and exploding. All but about 10m of the tail section is practically atomized by the impact. Apparently the crew reported a bird strike before they attempted the landing. That’s all I know to this point.

Why is the gear up? There is no explaining it. There is never a reason that a pilot would not want even just one extended; the others refusing to extend. A single main gear provides much-needed braking while the other side is kept off the ground until full aileron no longer is able to do so. A nose gear without the mains (might) provide some steering capability. I do not see how it is possible to not be able to extend at least one. And I find it unlikely to the extreme to be unable to extend them all. With both hydraulic systems inoperative, the gear simply freefalls. There’s a little door on the floor of the flight deck. You open it and pull three long cables which release the uplocks. Why not land fully gear up instead of a partial extension? Because the metal belly and engine pylons provide very little friction against asphalt. Metal melts away almost viscously and the result is more like hydroplaning than breaking, at least initially. Another odd thing about the video, at least as far as I can tell after a dozen views, is that the speedbrakes do not seem to be extended. This is absolutely to very first act of the crew the instant the metal hits the pavement. Normally it’s automatic. But without wheel spinup, the handle has to be pulled. Is it possible that there was no hydraulic power to drive the speedbrakes? It’s possible if both engines were so wrecked by birdstrikes that they had nothing. (Sully’s scenario). The landing APPEARS to me to be with at least some flaps and/or slats extended. If so that would mean at least one engine was running.

But not necessarily at touchdown. It could be, in fact I hope it turns out to be, that some event (birdstrike) took out both motors early on the approach, leaving the crew insufficient time to pull the handles and no way to configure further. On glidepath, even engineless, they would have enough potential energy to continue the approach to the runway surface. With a strong enough right crosswind, at some point the cable-driven rudder would be unable to overcome the weathervane tendency of the airplane. If this is what happened, then the crew AND the Boeing did the very best they could with the hand they were dealt.

[EDIT] Responding to @Troll below. That’s wild about the KLM over-run! It is just the type of incident where full knowledge benefits us most WHILE likely being the one we will hear nothing more about. This lack of communication is the biggest barrier to the elusive goal of perfect safety. Even internally within my airline, we’re mum about incidents like the KLM one. We blame lawyers and, yes, that’s part of it. But really it comes down to the very complex business of safety investigation. So what do pilots do?

They speculate. Which is what I’ve done above. We simply have to do it. To stay mute and not process the horror of it is not the answer. Neither is throwing the crew (or the plane) under the bus. I hope I’ve done neither with what I wrote above. To reiterate @Troll’s point, and I agree completely, the above is one of dozens of scenarios and almost certainly it is wrong. But wrong in a technically informed sense if you get the distinction.

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It is indeed impossible to tell the story with the limited evidence at hand and a lot of questions remains to be answered.

Just yesterday a KLM 737 made an emergency landing at TRF (ENTO) here in Norway, stating hydraulic issues shortly after departure from OSL (ENGM) and went off the runway.

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My first correction. The video I originally watched was angled in such a way that the plane appeared to veer right. A second video clearly shows it overrunning the end straight ahead and striking the wall.

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The “concrete barrier” it plowed into was the localizer. My understanding is that ICAO requires that structure (and anything else in that general area) to yield under impact. It clearly wasn’t made to ICAO regulations and, in my opinion, is the final hole in the swiss cheese that probably would have been a more survivable event regardless of the gear up/flaps up weirdness going on.

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There’s nothing wrong with that.
It’s good practice to review what we know and can process. What could’ve gone wrong? What countermeasures are available if that’s indeed what happened?
By speculating what might have happened we brush up on knowledge of the associated systems and the emergency procedures.
We can’t assume that we know what happened though, but that’s something else entirely.

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I know it is very early in the investigation. Was the engine damaged by the bird earlier in the flight still operating? My guess is that the damaged engine started to send fumes and smoke into the cabin and cockpit and the pilots never decided to shut it down…or did not do it properly…and the bleed line never got shut off. A bit of panic…poor decision-making…and possibly extraordinarily poor airmanship.

I know these are harsh statements without enough knowledge…and I’ll certainly retract them if the conditions were such that the outcome HAD to happen as it did. I just find it extraordinarily unlikely…

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I don’t doubt that about the localizer, a concrete wall was also involved as can be seen in photos.

I will walk that back too. I can’t find the photo showing the wall.

This is from my phone’s map ap…

The localizer array is standard, I think. There is a road (public or service, I don’t know). But I do think that there was a wall prior to the road.

There‘s always the possibility of two bad things happening at the same time.

Like the bird strike giving one pilot a heart condition or whatever.

80 dead, 2 injured, 99 missing. :slightly_frowning_face:

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I hope not. And I also doubt it. I am about to say something that will strike most readers as nutty, pilots are better than they used to be. Really. A generation ago there were WILD variations in crew standards worldwide. Today, pilots worldwide fly with a roughly equivalent approach to standards and crew resource management. I can easily see a crew in the 70’s get so hopelessly lost. I would be utterly shocked if it happened today.

[EDIT] COLOR ME SHOCKED! They did loose an engine and they did go around once (according to Al Jazeera). If true, I am as lost as anyone. There is no explaining it with the information now available.

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It’s funny (or I guess ironic) that the other night I got done flying at some zero dark thirty hour and was walking out to my car in the parking lot. Right about then…out of the murk a Prime Air 767 (I think) came roaring in…thrust reversers going…brakes wailing… Impressive as all get-out. And I thought to myself…this is happening thousands…tens of thousands of times a day all over the world. These massive machines of extreme engineering are plonking down on runways…super dynamic…lots going on and you’d think with the human factor of people flying these things…that you’d see more accidents. So I stood there and was impressed…by how safe it all is. How extraordinary it is that everything I had just seen was normal and routine.

But every once in awhile…I guess…

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And this is what makes accident investigation so incredibly interesting.
Instead of focusing on what the crew may or may not have done wrong, I like to think about why their actions made sense to them, in that situation. Because we can assume that trained professionals didn’t just sit there and knowingly made a bunch of mistakes. If they knew what they were doing was the wrong course of action, they wouldn’t have done it, would they? So, what they actually decided to do, or not do, made sense to them, there and then. Why?
They may have been limited in their options or in perceiving their options, but they didn’t just roll over and play dead. They fought the situation until the end.

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@BeachAV8R

Same. I am so impressed with not just the planes themselves, but with the operation. The tugs, the deicers, the bellow-the-wing guys and girls, the controllers. It is such a complex and beautiful dance and maybe I’ve become a bit TOO enamored by it.

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Yes…I cut my post short but meant to imply the entire “ecosystem” (Oh god…that word again)… Mechanics and technicians getting stuff right. Like you said…fuelers…tugs…luggage carts…catering trucks. It is an insane ballet of moving parts with people from all education levels…experiences… That it happens mostly smoothly is amazing.

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There is a wall prior to the road, but not one strong enough to do that much damage, and not where the plane impacted.


Here’s where I initially heard about the ICAO standards (then did some digging on my own) and about the localizer’s concrete construction, around the 12:30 mark. By “obstacles” he’s referring to the reinforced concrete base, not the antennas themselves.

From what I’ve been able to dig up in terms of documents regarding the ICAO standard, “Localiser supports (if located within 300 m from the threshold)” are to be “frangible” as of 2006 (?). Annex 14 & Aerodome Design Manual part 6, apparently.

That structure unfortunately wasn’t frangible enough and, according to Google Earth at least, is 260m from the threshold.

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It’s a bit of a red herring. There has to be an end somewhere. Here’s what I mean: We land on 5500’ runways. It’s short but safe. 1500’ later is something; a wall, a cliff, an ocean, trees, houses, whatever. We also land on 13000’ runways. Also safe. Safer, obviously. Those runways also have eventual, hard, ends. No one guarantees us anything past the EMAS and overrun. Their goose was cooked whether they hit the antenna or the next wall 0.16 seconds later.

Next wall would not have done as much damage as the localizer structure. It was plain cinderblock, not reinforced concrete. I’m also not saying their goose wouldn’t have been cooked, I’m saying it wouldn’t have been charcoal’d well-done. More survivors if the airport had followed standards (which Korea isn’t known to do well) is nothing less than a potential positive outcome in my view. One more issue of probably many their corner of the aviation industry needs to fix.

Is it even possible to have a red herring in aviation incidents? Red herrings are a single misleading cause, but these incidents involve a whole chain of causes, all of which contributed and need to be accounted for and addressed, IMO. We can’t just ignore all the stuff that happened after “incident zero” that kicked off the event.

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By “red herring”, I mean that the youtuber from your post has done what youtubers do, found controversy where none exists. All runways end at the end of the overrun. He knows that.

This is Hiroshima…

That structure is just a reflector for radar altimeters to work in autolands. It’s a straight plummet of hundreds of feet. Is it great? No. That’s what happens when you shave a mountain to make an airport. Is it safe? Sure. Safe enough.

(Responding to below). I am not going to go back and forth with you on this, Clutch. I only know what I know. It’s my job. I posted two photos of two runways. But numbered “10” with standard-sized markings. You can easily measure, just by looking at the threshold paint, the distance from the end to the “fatal barrier”, be it antenna or cliff. The Korean runway has more overrun and much more run to the antenna than the Hiroshima runway 28 has to the cliff. Every airport has its challenges. That doesn’t make it an outrage.

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The point isn’t whether there’s an object there or not, or where the runway ends. The point is whether an object there, within 300m of the threshold, is frangible per ICAO guidelines, and this one clearly wasn’t. That is not controversy, that is fact.

If that guideline had been followed by the airport, then one hole in the swiss cheese could have been plugged. One hole plugged is potentially less of a negative outcome. I don’t understand the invalidation of potential outcomes with defeatest dismissals of facts. When the investigation discovers the causes, they aren’t going to point at a singular cause and say “let’s fix the first or largest hole in the cheese and ignore all of the others.”

It doesn’t matter if it’s your job, what you’re arguing is a straw man fallacy from misinterpreting what the Youtuber and I are saying. And throwing in “it’s my job” to waive away my (our?) argument without properly addressing it is an appeal to authority fallacy…and no one said anything about an outrage? Where did you get that? I mean, is your dismissal of a 737-800 pilot’s thoughts purely based on the fact that he’s a YouTuber? What makes him less of an authority than you given it’s also his job to fly these things?

I’m just trying to lay out a logical, evidenced-based take on a small portion of this while trying to avoid bias, sheesh.

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OK, so ignoring the previous section of the discussion, I am going the toss in another form of pure conjecture: maybe they were not aware that they had not extended the gear. This is not impossible. Many years ago, at (shame) my airline, a crew landed a DC-9 in Houston totally clean; no gear, no flaps, no slats. There was nothing wrong with the plane. The two pilots were one-uping each other with Disney character impersonations. In the CVR recording can be heard a myriad of warnings while the two pilots are laughing like Donald Duck. The plane touched down at 170 knots and slid to a stop. No one was scratched.

This crew did something additionally weird: they deployed at least one reverser. That would be a crazy move if your INTENT was to keep the gear up. But it makes obvious sense if they thought the gear was down. Also, they held the nose off (aerobraking only works in fighters). This makes sense if you want your landing to look and feel heroic. But it makes no sense if you are scraping metal. All you do is reduce the contact surface and, well, F=ma.

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I was thinking that as well after I dug through a bunch of info on the hydraulic systems and manual gear release. There was news elsewhere from translated Korean text messages from someone on the fight mentioning smoke in the cabin but that’s unverified. I can see them not realizing the gear is up while dealing with the checklist for the bird strike or whatever else; I’ve done that in less severe circumstances in DCS plenty of times.

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