What is the situation of the on-site investigation of the Infinite Airport plane accident?

■ Host: anchor Sung Moon-gyu
■ Starring: Professor of Safety Engineering at Eulji University, Ham Eun-gu, Professor of Fire and Disaster Prevention at Korea Open Cyber University, Baek Seung-ju

* The text below may differ from the actual broadcast content, so please check the broadcast for more accurate information. Please specify [YTN News Special] when quoting.

[Anchor]
We will continue to bring experts to update you on the Muan aircraft accident. We will join Baek Seung-joo, a professor of fire and disaster prevention at Korea Open Cyber University, and two professors majoring in safety engineering at Hameun-gu District. Of the 181 passengers, all 179 were confirmed dead except for two crew members. How do you figure it out?

[Baek Seungju]
The cause of the accident is believed to be the cause that can be estimated after being concentrated on bird strikes in the first place. However, in the process leading to such a disaster, landing as a fuselage in which the wheels did not come down just before the fire exploded. And the Mayday situation that before that, there was smoke, a fire engine. These are information that can be found through clear reports. Most of the data collected the flight recorder and the data collected before that should be connected through this analysis. In the part that there was an engine failure, which was the direct cause of the massive disaster, and there was a problem with the landing gear, the briefing of the Ministry of Land, Infrastructure and Transport, as well as the reports and videos reported.

[Anchor]
So, as Professor Baek said, what has been confirmed is that the engine gear is broken. It was shown on the screen that it was broken by a certain impact, and the landing gear was not unfolded. The wheels didn't come out. That's how the facts can be organized. How do you see Professor Ham?

[Hangeungu]
As you've just mentioned, the direct cause seems to have been caused by an accident in which 179 people were killed when the landing gear failed to slow down properly and collided with the outer wall of the airport.

[Anchor]
The problem with the aircraft on the surface is that it is seen as such, so why did the landing gear not unfold? This is the part that I can't check right now. What do you think of Professor Baek?

[Baek Seungju]
You have to go through everything. It is now recorded as the biggest aircraft disaster in Korea. And I see it as 90 seconds in the aircraft Goulton time. The golden time for survival is. So, evacuate quickly in the early stages. We don't even train fire extinguishers on board an aircraft. It's because immediate evacuation is important. In fact, the two-hour announcement increased the death toll at the official briefing, but the actual victims of the disaster occurred at that time. So, the national sentiment that we share the sadness of the victims has delayed the accident without clarifying the predictive damage situation in advance, but I think the fire department has accurately grasped that the disaster began by seeing the active declaration of a disaster zone or the third stage of the disaster. Nevertheless, the Ministry of Land, Infrastructure and Transport is investigating this part that the landing gear was not unfolded, but the part clearly shown in the report video is that this aircraft itself has one front wheel under the head and two behind it, and even if it is not visible due to dust and flame smoke behind it, it is clear that the front wheel has not come down. And if the rear wheels are down, you can't see the wheels, but if you look at the screen, it's clear that there are no front wheels, and you can't see the rear wheels, but the engine on the front wing is attached to the floor. So you can fully infer that it came down because there is no rear wheel. So it is clear that the landing gear was not unfolded, but this part must have been because of the collision of the current, or it is a physical impact. I mean, maybe not. Therefore, even if you look at the wordings of the Ministry of Land, Infrastructure and Transport's briefing as a fact, it is said that the relationship and the reason are being investigated. That's why they say this at the 5 o'clock briefing.
In any event of a crash, there is no interlocking failure that leads to a failure of the landing gear not to unfold due to an engine failure. It can't be connected. But if there is no mechanical connection, this can be human or environmental. So by predicting, it's a problem for us to narrow down our accident investigation, but in this case, we have to go through the process of creating all the scenarios and erasing the impossible ones one by one. That's why, in terms of estimating and adding scenarios, that aspect can also be a connection.

[Anchor]
That's what I'm saying. First of all, the right engine is broken, and what you just said is that the failure of the right engine cannot be seen as a direct cause of the failure of the landing gear even in the announcement by the Ministry of Land, Infrastructure and Transport. How can that be explained mechanically?

[Hangeungu]
As you mentioned, the aircraft is a kind of transportation that needs to be focused on in terms of prevention, so we have devices that perform the same functions in parallel. As you said, these things should be operated independently without interworking with each other to create an environment in which reliability can be increased by various conditions.

[Anchor]
That means that if the wheels don't come out just because the engine is broken, it's a big accident, so I separated it functionally in the first place.

[Hangeungu]
That's right. We have this system that is functionally completely separated. And even if there are mechanical defects or conditions by giving up ten minutes, there are various ways to deploy them in manual deployment or in various situations. The condition that all of these things are neutralized. As I said, these are very low probabilities, so the exact cause of these things seems to need to be revealed closely through black boxes or something like that.

[Anchor]
Anyway, it became a major disaster while trying to land the fuselage, and even before this, I sent you our report, but the shooting down of Korean Air was in 1983, and 269 people died at that time. Also, was it in 1997 that a Korean Air plane crashing to Guam crashed in Guam? That's when 225 people died, and this is the largest aircraft accident since then. 179 dead First of all, the landing gear was not unfolded, but the fact that it hit the outer wall and led to a fire as if the aircraft completely exploded could cause a huge death, what do you think?

[Hangeungu]
That's right. One of the reasons for the extreme expansion of the damage to the form of a disaster seems to have been accompanied by collisions with the outer wall. However, there is actually a little inconvenience in the area where the outer wall is said to be the cause. So, these outer walls are actually structures that are installed without any design problems.

[Anchor]
What is that outer wall like? Is it just the border of the airport? What is it?

[Hangeungu]
That's right. Also, since it's a security facility at an airport, it's not a facility where outsiders can come in and out. So, this form of minimal airport boundary exists as an outer wall. However, as a result, the aircraft slid to the outer wall when the unfortunate parts were not actually fully braked. In particular, as I said, the aircraft itself has no concept of mitigating various impacts or reducing damage when colliding with the outer wall in terms of material or characteristics. So, such a physical shock unfolds to passengers. In this process, as the anchor said, it seems that it acted as if it were the cause of the harm.

[Anchor]
When we build a car, we have a bumper, and the car itself is made of very strong iron, so how can we impact it? . We do crash tests several times, design the car, build the car body, and use the material, but that's not the case for airplanes.

[Hangeungu]
That's right. The design concept itself is about lightening. As it is now, maintaining the rigidity of the aircraft body itself under the condition of the outer wall and physical impact is not considered. Most of these aspects are considered to ensure safety in thunderbolt and other areas, but as you said, it is not actually considered to increase structural safety by using bumper or safety pack like the body.

[Anchor] Professor
Baek majored in fire and disaster prevention. The screens of the day of rescue activities are coming out, and you mentioned the golden time earlier. How do you see the firefighting's response during the day?

[Baek Seungju]
First of all, the model has six emergency exits on the front, middle, and rear sides. And when you design an airplane, you don't have a compartment or a fire-fighting system in a typical building, but you have to be able to complete the evacuation through half of the emergency exits with a full number of people within 90 seconds of golden time, and that's the design standard. Golden time. Because it's a collision in an emergency situation and it can immediately lead to a fire. The two survivors who eventually become the flower of hope in this disaster, if you look at the hospital briefing earlier, they suffered compound fractures in many places, but there is another part that does not have a serious burn. So, the tail seems to be in the form of a landing tail in the video, and it seems that there was a physical collision, not a flame, when it crashed while under excessive force in the back of the landing.

[Anchor]
It's broken in half.

[Baek Seungju]
If that's expected, it can be estimated that the two people in the back can be connected. Also, if you look at the video of collecting debris and the video of the firefighters. Not all of them burst into the lineup, and there seems to be Busanmun before. That's why there was grinding right after landing in the early stages. And because the time from the aircraft's leaking flames, ignition, and fire explosion was relatively broken, there would have been insufficient time to deploy safety lamps, emergency ramps, physical conditions, and it would have been difficult for passengers to evacuate on their own without crew assistance and in a physically broken state. That's why there's another situation that led to a fire. Therefore, it is difficult to delay the internal suppression structure of the external fire brigade, which is not the initial external or internal crew, or the delay due to these activities. It is presumed to have been such a situation both physically and temporally.

[Anchor]
I don't know how to express this, but the Jeonnam Fire Headquarters held a briefing like this. I used the expression that passengers poured out of the aircraft after colliding with the fence. So, I think the physical collision was very strong due to the physical collision at that time, but I should ask Professor Ham about this. So, the direct cause of death is the collision itself, and the fire is also a fire. I think the impact of the collision was very severe.

[Hangeungu]
That's right. Even if you look at the video now, it's like that. And as you said, if you look at the shape of the debris in the process of witnessing and repairing the firemen, it actually collides with the outer wall, and the strength of the outer wall itself is very strong in some ways. You can't see it like this, but at least the carbon steel or aluminum that I mentioned, so the outer wall was relatively stronger. In fact, the body of the airplane itself is physically affected by that part, so if the outer wall falls or develops in this part, it may be less damaged.

[Anchor]
I know. If it's a normal exterior wall, you have to go through it at that speed. Is it because it's the end of the runway? I think the outer wall was quite strong, now that I think about it.

[Hangeungu]
As I said, the basic body of the aircraft itself is a very soft metal called aluminum, so when these things actually hit the structure, to put it a little differently, in terms of action and reaction, it actually shows that all the impact was transmitted to the aircraft itself. So, as you just said, if people in the aircraft actually say that the aircraft cannot withstand the structural part and are completely shocked, it will break down in a completely completely destroyed form, and many people may have died from the impact.

[Anchor]
How do you feel when you look at the screen? The speed that's landing now and dragging the bottom. There must be that speed when you land in a normal way, normal landing speed. And what do you think about that on the screen?

[Hangeungu]
It's hard for me to tell you exactly how compared to that with the naked eye. Anyway, the parts of the gas fuselage are designed to reduce friction as much as possible. In the end, in the process of sliding while contacting the ground, this so-called grip force resistance will not be high. In the end, if air resistance or these are conditions that affect a certain braking, it's seen as a condition where the speed is almost uncontrolled, that is, almost sliding. That speed... Usually, it's known that an aircraft of that speed is about 140 knots when it's actually landing. Based on the video alone, it seems that the speed has been developed to some extent in terms of horizontal maintenance in the process of landing, but in the end, it is seen as a process of continuing without slowing down due to the lack of normal braking or such parts.

[Anchor]
I want to talk about this. Muan Airport is the beach. There was a water called the sea. Not long ago, it's not accurate, but there was a time in the United States when the Hudson River made a fuselage landing in the Hudson field on the New York side. At that time, all passengers were alive and landed without any casualties. So it was water everywhere, it was the ocean. I also think what it would have been like if I had done that, but Professor Baek.

[Baek Seungju]
That may be a way, but first of all, the number one cause of death in an ocean accident is not drowning, but hypothermia. For example, when the central temperature of a person's body reaches 30 degrees Celsius or less, hypothermia occurs from then on. Since the golden time is rapidly reduced to less than 30 minutes, it may be another way to judge it as the sea when landing at the airport, but it may be a dangerous factor in the worst-case scenario. Earlier, the pilot declared Mayday, and Mayday is a rescue request, and it manifests when the pilot cannot stably restore control through control or physical judgment. Then, if the previous situation had already been attempted to land and the engine failure had increased, in fact, we didn't use the word accurate writing in the Department of Land, Infrastructure and Transport briefing as an attempt to land the fuselage. The reason why I'm saying this is because when we think of a fuselage landing, it's landing gear, and when we land on the ground without wheels, it's landing on the fuselage. This is also true, but officially, when it comes to a fuselage landing, another fuselage landing is to go through the manual procedure while the pilot, control tower, and ground response team are fully prepared. However, changing the landing direction of the plane in such a short period of time that the fire department cannot take countermeasures and exhausting fuel through circling flights is also a procedure for fuselage landing. However, given that there was no procedure to raise the altitude again and fly around, it seems difficult to change the landing site in that situation. That's why if you didn't go into the fuselage landing in an official procedural manner, you could literally have reached a situation where you couldn't prepare for anything without the landing gear being unfolded and you couldn't judge an alternative. Actually, it's all different. We are curious about the cause, and the safety devices are not seen before and after.
That remains quite a question.

[Anchor]
It looks like it's in chronological order by time zone on the left, but the part you just mentioned issued a bird collision warning at 8:57 and the control tower. But the pilot asked for Mayday's rescue for 59 minutes. And the second attempt to land was at 9:09 or May Day. You didn't have time to tell me that you tried to land in a minute or two.

[Baek Seungju]
That's right. The pilot said it was runway 1 at 57 minutes and runway 19 at 9:01 minutes, but he changed it to runway 19 right after May Day. He tried to land from the north direction, which was 10 degrees wrong, but changed the term after saying, "This is a bird collision warning, and at 3 o'clock, it's an alarm." It's translated into English. So I changed it to advice. Then, it turned 19 times, so it turned 180 degrees completely south. So there was the May Day Declaration that came down in that situation without going north and turning back to its original position. It's not official here, but if you look at the passenger's report video, there is a kakaotalk phrase that a bird is stuck in the wings through kakaotalk. But if you look at the video of the report, it's filmed at 9:00. However, even if you think there is a one or two minute error between Kakao Talk and the timeline, the May Day declaration may have led to the collision after giving bird collision advice and warning. That's why around 9 o'clock, the family caught a bird in the wing, and this can be determined whether it is stuck in the wing or the engine attached to the wing. So in that situation, it can be a situation where you can turn to Mayday and go back up and come down as it is. In that case, the fire brigade on the ground cannot respond at all. For example, in the case of Muan Airport, the fire brigade has its own fire brigade as an international airport. Officially, there are three fire engines and 34 firefighters as their own fire brigade, and when it comes to fuselage landing as an official procedure and emergency procedure in dangerous situations, the fire brigade is divided and deployed after the runway. And the fire brigade with the highest firepower was deployed at the end. We also have a procedure for applying fire extinguishing foam to the runway. This depends on the level of equipment you have, but the fire brigade's deployment alone proves that if you changed the runway direction 180 degrees right after the May Day declaration, you didn't officially decide to land the fuselage before that. Because the fire brigade's position changes from the end of the runway to the end, the location of the operation. In that sense, after the May Day declaration, there was a situation where we had to land in the fuselage. That's why we wouldn't have officially decided to land the fuselage. So it can be inferred as a writing to investigate where the landing gear is not clearly unfolded. Because the Ministry of Land, Infrastructure and Transport has no choice but to say wording only with clarity, so I think we can assume that it is not.

[Anchor]
What is the best judgment in this situation if you share the fact that the real airplane pilot and the control tower are in a very difficult situation with the authorities anyway. You have to choose what options you can get off, but you just interpreted that such a situation happened without time before you even decided that the best option was to land the fuselage.

[Hangeungu]
As a result, if we look at the exact contents of the conversation and the passengers' messages comprehensively, we can infer the same as Professor Baek you just mentioned. The problem is that in any case, in conclusion, these parts actually appeared in the form of conclusive thinking called fuselage landing very urgently. The premise here is that the pilot, the captain, or those who are actually operating here, considering the very normal technology and these parts, the plane was not properly controlled and the landing was made in an urgent situation. It can be seen now. So one thing is that the plane can't turn properly and try to land again in just a minute or two, as you just said. And a lot of it, as the aircraft said, has some landing requirements while keeping level, so in these processes of landing while actually keeping some level even when the landing gear doesn't work properly, that is, conditions that are not well controlled enough that we can't actually raise the altitude or enter the runway that we just mentioned. Nevertheless, the condition of staying level and landing again to some extent. So there seems to be a need to actually take a close look at these things. I wonder if it was a situation where I couldn't raise the altitude because it didn't output perfectly.

[Anchor]
I see. You're looking at the new graphics. First of all, the outer wall is south. The outer wall is south and the opposite side is north, so you originally have to land from south to north. Runway 1 on the right is runway 1, right? Runway 1 on the right, if it was normal for the first time, we should have landed then, but as you can see, the first landing attempt at 54 minutes, the plane came up again, and the control tower told us to be careful of a bird collision in 57 minutes, and in just two minutes, we sent out a rescue request, after declaring May Day. And from the other side, from the north, they came back down and landed on the runway next door. The runway next to it is called runway 19, and we landed there. However, as Professor Ham said, the fuselage was balanced, but the speed was not reduced, and the accident occurred while landing. But you said it briefly in the previous session, too.If Ma is normal, it's right to try to land on runway 1 again.

[Hangeungu]
As the anchor said, the control tower actually gave a bird warning, and the birds appeared on the runway, so whether the control tower changed the runway with accurate writing. In that regard... Anyway, if you look at the records and things like that, you can see it clearly. But if you look at the shape of the accident now, it is known that the landing gear and other parts did not work properly at that time. So in this process, the process of landing by turning the direction anyway. In particular, it slows down the aircraft too much. If you look at it, you may not be able to meet the standards for a sufficient amount of lift and education. So I think that's what I said earlier, 140 notes. While maintaining that kind of speed.

[Anchor]
How much is 140 knots?

[Hangeungu]
If you think about it, it's about 80. in that kind of situation...

[Anchor]
You're talking about the speed of landing when it hits the ground, right?

[Hameungu]
That's right. That's how much I checked. Isn't various conditions reflected in that kind of situation? In the end, the biggest reason may be that the landing gear has not been deployed, but in the end, as Professor Baek said earlier, it seems necessary to closely examine the conditions for landing so urgently when there is not enough time for these agents to prepare and even various manuals are not followed.

[Anchor]
We're continuing to talk about the cause of the landing gear, but anyway, the bird collision is clearly pointed out as one of the causes of the accident. But not all of the planes that had bird collisions had accidents like that. How do you see it this time?

[Baek Seungju]
Bird collisions can get stuck in the wings, interfere with provisions, and get stuck in the wheels to interfere with landing gear operation. It can also fly into the engine, shut down the engine, and break the cockpit window of the aircraft, and cause various situations. But that's because the probability of two major causes of the major disaster of single risk at the same time is as low as two lottery tickets, so that may be the cause, but it's very difficult to presuppose. But now, the engine failure that is difficult to fly and the landing gear deployment that is difficult to land are two parts of the failure. I think there will be a lot of strain in this area. I'm not just the whole thing, but if there's homage in some of the processes, there was a case in which the largest aircraft in the country landed without opening the landing gear at Daegu Airport in 1991. There were no major casualties. The reason why the landing gear was reached only by the fuselage without spreading it was that the captain and the assistant manager later decided to land the landing gear with each other, and also cut off the emergency alarm power circuit in advance. Since it's in that state, we try to land without wheels. I checked with the naked eye at the control center, and when I heard the status of the transmission and reception, I thought the gear came down even though it was perfect to maintain it. In that situation, if the partial homage is based on the premise that there is a low probability of a tidal current collision caused by a mechanical failure leading to a landing gear failure, in this situation where it declares Mayday, it changes the landing route 180 degrees and then it's an emergency landing in that situation, itself, due to engine failure. Whether it's a bird collision or whatever. At that time, it is highly likely that the warning light was ignored or turned off during the transmission and reception process with the control station. If that happens, if it is concentrated on this part, the landing gear operation may fail or the state of not operating may be connected. But again, if I take this as an investigation into an accident and draw multiple scenarios into one scenario like this, it's a confirmation bias. But it adds a lot of scenarios, so predicting that it would have done this is a major obstacle to revealing the clear thinking process. So there are some homages like this, so I'm telling you again that we have to look at the details that may have been like this.

[Anchor]
That's what I'm saying. A number of complex accidents occurred at the same time and how they happened at the same time, so the cause of the accident is now just a guess and an unpredictable situation. I'd like to ask Professor Ham one last time. First of all, aren't most airports on the beach right now? Incheon Airport, Gimhae Airport, Gimpo Airport, and Muan Airport were by the sea. Birds have appeared and usually birds appear on the beach, how do you see this? Cause of accident and location of airport. How do you analyze it?

[Hangeungu]
As you just said, it's the same in Korea. Of course, it is quite reasonable for most airports, especially in a country with many mountainous terrain like Korea, to designate a coastal flatland as an airport. As you just mentioned, it's the same with Incheon International Airport. Especially in this time of wintertime, airports are trying to chase birds to the point where it's too much of a war against birds, or at least prevent the so-called bird strikes that are now supposed to be. So, the Muan Airport also has a system like this that deploys manpower to observe such parts and issue alerts. But there are a lot of things like this. As you said before, in fact, there is a very low probability that various conditions are realized at the same time, so in other words, bad conditions are realized. So, in fact, rather than the danger of these currents, the benefits of such coastal areas and especially those in contact with the sea in Korea are much greater, so there is a risk of space in these areas, but it seems that they are sufficiently playing a role as an airport.

[Anchor]
The right location for the airport is the coastal area, and migratory birds also like to go to the beach, so it's inevitable that birds appear at the airport anyway, so how can we avoid that? How can you chase a bird well? I'm continuing to work on these methods.Anyway, this is the place of migratory birds, and the period is the time when migratory birds come and go, so it is a situation where everything inevitably leads to accidents at once. That's all for the help. I was with Professor Baek Seung-joo and Professor Ham Eun-gu. Thank you both.