The Engineered Materials Arresting System (EMAS) is designed to decelerate and bring to a halt aircraft that overrun the runway. It is a series of ceramic tiles that are progressively broken by the aircraft wheels. However it is limited to 70 kts and will not work without the undercarriage being deployed.
@@TheUrantia001 That is not what the manufacturers say. A further problem is that the retardation per unit time, at high speed, the dwell time in the EMAS is short, so longer runoff areas would be required. Many airports have building developments close to the ends of the runways and limited safety areas. These have been reduced as the runways have been extended. This is one reason EMAS was developed, to make best use of the safety areas. During this accident the aircraft attempted a flapless landing. Also the spoilers were not deployed. In this configuration the wing would have been generating some lift, reducing the pressure of the aircraft on the runway. The three points of contact are relatively large compared with the contact patch of the wheels. The result is that the coefficient of friction is low and hence is the retardation. With the undercarriage extended the wheels exert sufficient pressure to break the EMAS ceramic tiles and dissipate more energy. During this accident the aircraft would continue to skid on the unbroken surface and the resulting retardation would be similar to that achieved on the runway.
In the case the aircraft was approaching at 200 kts, which is the correct speed for a flapless landing. In order to stop on the runway it would have to at least 6,000m long. Runway 19 is usually 2,800m long, but due to construction work (extending the runway) only 2,500m was available. The longest airport runway is 5,500ft. If the aircraft had not hit the ILS installation, 70m beyond is the airport boundary wall which encircles the airport. It is a security installation, because the military also use this airport. It has several layers, including watchtowers and a service road within the perimeter. There is a public road just outside the wall. If the aircraft had not hit the wall, 1,200m further (4,000m from the threshold of the runway) there is a hotel complex and other building along the shoreline, which the aircraft would have hit. Beyond that is the sea. Without flaps & slats this landing was never going to have a happy outcome.
So it sounds like a multiple systems failures. So sad. Did you see a picture that the pilot had his hand on a ceiling control 1 second before the crash? He was still trying to control the plane! So I doubt he panicked. I wonder what might have happened if the pilots hand belly landed on the grass?
Recently the Cockpit Voice Recorder (CVR) and Flight Data Recorder (FDR) have been downloaded and it was found that both recorders stopped recording 4 minutes before the accident. The FDR is powered by the AC Transfer Bus 1, which is a 115V 3 phase 400Hz supply, which is normally powered by the No 1 engine driven generator. Similarly the CVR is powered by the AC Transfer Bus 2, which is a 115V 3 phase 400Hz supply, which is normally powered by the No 1 engine driven generator. If one of the generators trips offline there are cross ties which enable both transfer buses to be energised by the good generator. The second generator fails, then all AC 115V 3 phase 400Hz is lost. If running the APU can also provide this supply. Losing both generators is an indication that both engines have failed. The hydraulic systems A & B are normally pressurized by the engine driven hydraulic pumps, fitted to the main engines. If one engine or the hydraulic pump fail, these systems can be pressurized by an electric motor hydraulic pump. These pumps utilize 115V 3 phase 400Hz from the AC Transfer Bus 1 & 2. So If the APU is not running, with a double engine failure hydraulic power and AC power are lost. In this situation the aircraft cannot be configured for landing. That is the undercarriage and Flaps & Slats, cannot be deployed. The the undercarriage can be deployed by gravity, by releasing the locking latches. This requires a panel behind the co-pilot's seat to be opened and thee handles pulled extending the attached cables by about 5ft. This takes time. Without hydraulics and AC power the aircraft can still be flown as the pilots' controls are connected to the flight control surfaces. The aircraft does have 28V DC aircraft batteries, which can supply power to essential systems. There is a modification so that the CVR is provided power by the Recorder Independent Power Supply (RIPS), which provides a backup supply for 10 minutes after the AC power is removed. This modification was not installed in the incident aircraft. About half of the jeJu Air fleet of 40 aircraft do not have this modification. There is no battery backup for the FDR.
The aircraft hit an ILS Localizer Antenna Installation, which was built by the US military when the airport was an airbase. It was originally constructed the the 1950's and latter (when still a US base) it was modified. The South end of the runway is lower than in the middle so the Antennae need to be raised, it was also prone to flooding and the foundations moved in the saturated earth. This necessitated frequent calibration of the installation. The solution was to build a reinforced concrete raft an to mount the antenna on top. The construction and location is compliant with the current International Civil Aviation Organisation (ICAO) guidelines, because it is far enough away from the end of the runway to be out of the safety area. The Instrument Landing System (ILS) permits the aircraft to land in poor weather conditions. The Localizer provides the pilot with positional information, with respect to the centerline of the runway. Hence the ILS antenna has to be on the runway centerline. Structures built within the safety area must be frangible and the foundations shall be level with the surface.
@@TheUrantia001sounds like you are biased towards *"overrunning over 120kts is common and perfectly survivable".* You fail to notice 99% of runway overruns are below 20kts, 80% are below 10kts. 99% are with landing gear extended. Concrete foam arresting device is inefficient without at least the main landing gears extended. You also fail to notice a fck ton of airports/runways in the US alone are no better than this at clearing open area with frangible structures beyond, let alone in the entire world. Also, classic jetliner structure is good at belly landing on a paved stable profile runway. On the grass however, especially with variable slope, and inconsistent dirt/mud density, the odds leave the "stable structural integrity" domain to randomly reach the catastrophic structural failure realm every second. It being a ditch, a pond, a brick wall, a road (with variable edge levels of different density), a warehouse, a parking lot... *At that speed, it doesn't matter what you have 90m beyond the end of the runway, it will be deadly!* What would have happened if that pile of dirt wasn't there? - we have uneven down slope dirt/grass, like most airports in the world. Chances to get one or two engines ripped off are high, severing main wing tanks along the way. Bad, real bad. Note that near the perimeter fence, the ground slope comes up again, that will be enough... - assuming both engines remain attached, you meet brick wall standing on top of concrete footings, that small one feet base is enough to crush and poverize both engines, then deform wingbox structure (forces dispersion through the structure), this vaporize kerosene into droplets in an instant in all directions: the nature of the impact doesn't change the fireball outcome if you let kerosene get crushed, escape and disperse that fast. Not having that pile of dirt won't prevent explosion. By the way, the entire lower nose would have desintegrated upon hitting the wall basement, deforming the cabin into a mangled mess, seats rows torn forward, one third of passenger and the pilots instantly died. - but a 737 is ~60 tons overall. A brick wall can't stop that, too frangible. Therefore, now you have several chuncks of hull and people strapped in ripped seat rows propelled airborne while burning, and since no impact is even, all those debris and bodies are spinning, then drifting/skidding on uneven terrain after secondary impact (road and grass). Those inside wrecks will slide farther (less friction and more roll, more centrifugal dispersion getting airborne/no-drag again) Other less lucky will find a terrain obstacle and abruptly stop with a force of over 100g. Mostly deadly after a few seconds of burning sensation. - By the way, the tail section... Since the aircraft opened a hole in the wall, that tail will pierce through whatever is in the way, there's an APU there, structural stabilizers reinforcements and cabin pressurization dome. A nice uneven heavy projectile... Hope your two flight attendants in the back are well strapped and lucky enough because instead of flipping over once to disperse impact force efficiently at the expense of a crushed fuselage, now they enjoy a 300m roller-coaster ride through shrapnels and fire. - Now what: firefighters on site can't cross that wall with burning debris, concrete rubble, no road. Now they have to go back to the barracks, reach the gate nearby, drive outside the airport all the way to the crash site extension on the perimeter road. If someone is alive there still trapped in the burning carcasse chuncks of some fuselage section, better hang on cause it will take a while... All of that because "we prefer the entire fuselage to survive overruning at that speed..." (facepalm) A car at 100kts can stop fast and occupants can SURVIVE because the car is DESIGNED TO SOME EXTENT TO EFFICIENTLY DISPERSE HEAD ON IMPACT FORCES. That's also why cars can't fly, they are too heavy. Aircraft don't have that luxury. Now, propel a car at 130kts, make it drift to lose friction just like that 737, and make it veer of the road, it will start to roll, catastrophically desintegrate, possibly eject its occupants. That's just 1 ton car, a 767 is 60 times heavier, with thousand times more fuel, and a cabin as weak as paper at the scale of involved forces. Stop watching Hollywood movies if you can't understand plane crashes in those are fiction, none of them are anywhere close to what happen in real life, especially that stupid misconception of a fuselage getting out pretty much intact after several impacts.
@@TheUrantia001 BTW, those focused on that dirt pile are the one leaning towards blaming some side, at all costs. Those who are not are not interested in protecting anyone, rather, HAVE THE REASONABLE PRINCIPLE OF GETTING THINGS RIGHT, like finding out the actual causes, cannot be accused of bias. The primary cause at this point is "ENERGY MANAGEMENT". In other words, manage your altitude and speed to have enough of both to reach the runway, without excess (if possible) to not overrun or at least overrun at a reasonable speed where the 90m dirt/grass after the runway end is STATISTICALLY ENOUGH to bring you to a stop. Not even the need of concrete foam. What happened which made you expedite a desperate landing, to the point you had no means to properly manage your energy? Did something else happened, like multiple bird strikes, or aircraft systems critical failure or aircraft not behaving as expected in training? (there's a lot ongoing discussions about electrical power and batteries, seems even EXPERIENCED 737 pilots EXPECT flaps to operate okay with engine #2 running, appears it's not the case) Those are the kind of questions that should be asked. Instead, many are blaming the pilots while other behind their screen are PRETENDING TO BE CAPABLE OF NOT MESSING A SINGLE DECISION AMONG A THOUSAND CRITICAL ONE. How much bank, what attitude, what order of switches at what moment...
Apparently lost both electrical busses as the ADSB transponder, flight data and voice recorder stopped working and lost 4 min of voice and data recording
Hi the crash didn't happen near Jeju in south Korea🤣(0:31) and I'm not sure you are allowed on youtube to show the actual crash sequence where people die!
@@vigilantcork248 I'm sure you meant well, but rest assured, everybody understood it was Muan, not Jeju airport. In social media platforms, that habit of picking up on typos has really become unnecessary. Nobody is perfect, not everybody speaks english. Re-editing and re-uploading a video, absolutely not worth it if the error doesn't lead to some terrible and unforgivable misunderstanding..
you never mentioned depressurisation of the craft upon impact with would cause explosion combined with heat..normally takes a few minutes to de-pressure.
The 737-800 is normally pressurized to 8,000 ft, below that altitude the pressure is increased to match that of the surrounding atmosphere. On landing the pressure differential would be almost zero and not contribute to the explosion.
The Engineered Materials Arresting System (EMAS) is designed to decelerate and bring to a halt aircraft that overrun the runway. It is a series of ceramic tiles that are progressively broken by the aircraft wheels. However it is limited to 70 kts and will not work without the undercarriage being deployed.
BS it would
@@TheUrantia001 That is not what the manufacturers say.
A further problem is that the retardation per unit time, at high speed, the dwell time in the EMAS is short, so longer runoff areas would be required.
Many airports have building developments close to the ends of the runways and limited safety areas. These have been reduced as the runways have been extended. This is one reason EMAS was developed, to make best use of the safety areas.
During this accident the aircraft attempted a flapless landing. Also the spoilers were not deployed. In this configuration the wing would have been generating some lift, reducing the pressure of the aircraft on the runway. The three points of contact are relatively large compared with the contact patch of the wheels. The result is that the coefficient of friction is low and hence is the retardation.
With the undercarriage extended the wheels exert sufficient pressure to break the EMAS ceramic tiles and dissipate more energy. During this accident the aircraft would continue to skid on the unbroken surface and the resulting retardation would be similar to that achieved on the runway.
In the case the aircraft was approaching at 200 kts, which is the correct speed for a flapless landing. In order to stop on the runway it would have to at least 6,000m long. Runway 19 is usually 2,800m long, but due to construction work (extending the runway) only 2,500m was available. The longest airport runway is 5,500ft.
If the aircraft had not hit the ILS installation, 70m beyond is the airport boundary wall which encircles the airport. It is a security installation, because the military also use this airport. It has several layers, including watchtowers and a service road within the perimeter. There is a public road just outside the wall.
If the aircraft had not hit the wall, 1,200m further (4,000m from the threshold of the runway) there is a hotel complex and other building along the shoreline, which the aircraft would have hit. Beyond that is the sea.
Without flaps & slats this landing was never going to have a happy outcome.
Tru but they would have had a better chance the death wall sealed the deal rip
Thanks for your precisions and absolutely agree! Wall or not, at this speed their would have something else on the way yo kill everybody...
So it sounds like a multiple systems failures. So sad. Did you see a picture that the pilot had his hand on a ceiling control 1 second before the crash? He was still trying to control the plane! So I doubt he panicked. I wonder what might have happened if the pilots hand belly landed on the grass?
Recently the Cockpit Voice Recorder (CVR) and Flight Data Recorder (FDR) have been downloaded and it was found that both recorders stopped recording 4 minutes before the accident. The FDR is powered by the AC Transfer Bus 1, which is a 115V 3 phase 400Hz supply, which is normally powered by the No 1 engine driven generator. Similarly the CVR is powered by the AC Transfer Bus 2, which is a 115V 3 phase 400Hz supply, which is normally powered by the No 1 engine driven generator.
If one of the generators trips offline there are cross ties which enable both transfer buses to be energised by the good generator. The second generator fails, then all AC 115V 3 phase 400Hz is lost. If running the APU can also provide this supply.
Losing both generators is an indication that both engines have failed.
The hydraulic systems A & B are normally pressurized by the engine driven hydraulic pumps, fitted to the main engines. If one engine or the hydraulic pump fail, these systems can be pressurized by an electric motor hydraulic pump. These pumps utilize 115V 3 phase 400Hz from the AC Transfer Bus 1 & 2. So If the APU is not running, with a double engine failure hydraulic power and AC power are lost.
In this situation the aircraft cannot be configured for landing. That is the undercarriage and Flaps & Slats, cannot be deployed.
The the undercarriage can be deployed by gravity, by releasing the locking latches. This requires a panel behind the co-pilot's seat to be opened and thee handles pulled extending the attached cables by about 5ft. This takes time.
Without hydraulics and AC power the aircraft can still be flown as the pilots' controls are connected to the flight control surfaces.
The aircraft does have 28V DC aircraft batteries, which can supply power to essential systems.
There is a modification so that the CVR is provided power by the Recorder Independent Power Supply (RIPS), which provides a backup supply for 10 minutes after the AC power is removed. This modification was not installed in the incident aircraft. About half of the jeJu Air fleet of 40 aircraft do not have this modification.
There is no battery backup for the FDR.
The aircraft hit an ILS Localizer Antenna Installation, which was built by the US military when the airport was an airbase. It was originally constructed the the 1950's and latter (when still a US base) it was modified. The South end of the runway is lower than in the middle so the Antennae need to be raised, it was also prone to flooding and the foundations moved in the saturated earth. This necessitated frequent calibration of the installation. The solution was to build a reinforced concrete raft an to mount the antenna on top.
The construction and location is compliant with the current International Civil Aviation Organisation (ICAO) guidelines, because it is far enough away from the end of the runway to be out of the safety area.
The Instrument Landing System (ILS) permits the aircraft to land in poor weather conditions. The Localizer provides the pilot with positional information, with respect to the centerline of the runway. Hence the ILS antenna has to be on the runway centerline.
Structures built within the safety area must be frangible and the foundations shall be level with the surface.
sounds like you are biased towards protecting a certain side
@@TheUrantia001sounds like you are biased towards *"overrunning over 120kts is common and perfectly survivable".* You fail to notice 99% of runway overruns are below 20kts, 80% are below 10kts. 99% are with landing gear extended. Concrete foam arresting device is inefficient without at least the main landing gears extended. You also fail to notice a fck ton of airports/runways in the US alone are no better than this at clearing open area with frangible structures beyond, let alone in the entire world. Also, classic jetliner structure is good at belly landing on a paved stable profile runway. On the grass however, especially with variable slope, and inconsistent dirt/mud density, the odds leave the "stable structural integrity" domain to randomly reach the catastrophic structural failure realm every second. It being a ditch, a pond, a brick wall, a road (with variable edge levels of different density), a warehouse, a parking lot...
*At that speed, it doesn't matter what you have 90m beyond the end of the runway, it will be deadly!*
What would have happened if that pile of dirt wasn't there?
- we have uneven down slope dirt/grass, like most airports in the world. Chances to get one or two engines ripped off are high, severing main wing tanks along the way. Bad, real bad. Note that near the perimeter fence, the ground slope comes up again, that will be enough...
- assuming both engines remain attached, you meet brick wall standing on top of concrete footings, that small one feet base is enough to crush and poverize both engines, then deform wingbox structure (forces dispersion through the structure), this vaporize kerosene into droplets in an instant in all directions: the nature of the impact doesn't change the fireball outcome if you let kerosene get crushed, escape and disperse that fast. Not having that pile of dirt won't prevent explosion. By the way, the entire lower nose would have desintegrated upon hitting the wall basement, deforming the cabin into a mangled mess, seats rows torn forward, one third of passenger and the pilots instantly died.
- but a 737 is ~60 tons overall. A brick wall can't stop that, too frangible. Therefore, now you have several chuncks of hull and people strapped in ripped seat rows propelled airborne while burning, and since no impact is even, all those debris and bodies are spinning, then drifting/skidding on uneven terrain after secondary impact (road and grass). Those inside wrecks will slide farther (less friction and more roll, more centrifugal dispersion getting airborne/no-drag again) Other less lucky will find a terrain obstacle and abruptly stop with a force of over 100g. Mostly deadly after a few seconds of burning sensation.
- By the way, the tail section... Since the aircraft opened a hole in the wall, that tail will pierce through whatever is in the way, there's an APU there, structural stabilizers reinforcements and cabin pressurization dome. A nice uneven heavy projectile... Hope your two flight attendants in the back are well strapped and lucky enough because instead of flipping over once to disperse impact force efficiently at the expense of a crushed fuselage, now they enjoy a 300m roller-coaster ride through shrapnels and fire.
- Now what: firefighters on site can't cross that wall with burning debris, concrete rubble, no road. Now they have to go back to the barracks, reach the gate nearby, drive outside the airport all the way to the crash site extension on the perimeter road. If someone is alive there still trapped in the burning carcasse chuncks of some fuselage section, better hang on cause it will take a while...
All of that because "we prefer the entire fuselage to survive overruning at that speed..." (facepalm) A car at 100kts can stop fast and occupants can SURVIVE because the car is DESIGNED TO SOME EXTENT TO EFFICIENTLY DISPERSE HEAD ON IMPACT FORCES. That's also why cars can't fly, they are too heavy. Aircraft don't have that luxury. Now, propel a car at 130kts, make it drift to lose friction just like that 737, and make it veer of the road, it will start to roll, catastrophically desintegrate, possibly eject its occupants. That's just 1 ton car, a 767 is 60 times heavier, with thousand times more fuel, and a cabin as weak as paper at the scale of involved forces. Stop watching Hollywood movies if you can't understand plane crashes in those are fiction, none of them are anywhere close to what happen in real life, especially that stupid misconception of a fuselage getting out pretty much intact after several impacts.
@@TheUrantia001 BTW, those focused on that dirt pile are the one leaning towards blaming some side, at all costs. Those who are not are not interested in protecting anyone, rather, HAVE THE REASONABLE PRINCIPLE OF GETTING THINGS RIGHT, like finding out the actual causes, cannot be accused of bias.
The primary cause at this point is "ENERGY MANAGEMENT". In other words, manage your altitude and speed to have enough of both to reach the runway, without excess (if possible) to not overrun or at least overrun at a reasonable speed where the 90m dirt/grass after the runway end is STATISTICALLY ENOUGH to bring you to a stop. Not even the need of concrete foam. What happened which made you expedite a desperate landing, to the point you had no means to properly manage your energy? Did something else happened, like multiple bird strikes, or aircraft systems critical failure or aircraft not behaving as expected in training? (there's a lot ongoing discussions about electrical power and batteries, seems even EXPERIENCED 737 pilots EXPECT flaps to operate okay with engine #2 running, appears it's not the case) Those are the kind of questions that should be asked. Instead, many are blaming the pilots while other behind their screen are PRETENDING TO BE CAPABLE OF NOT MESSING A SINGLE DECISION AMONG A THOUSAND CRITICAL ONE. How much bank, what attitude, what order of switches at what moment...
Apparently lost both electrical busses as the ADSB transponder, flight data and voice recorder stopped working and lost 4 min of voice and data recording
Hi the crash didn't happen near Jeju in south Korea🤣(0:31) and I'm not sure you are allowed on youtube to show the actual crash sequence where people die!
The crash occurred at the Muan Airport, which is in the SW of Korea.
@@christopherrobinson7541 Absolutely and not in "Jeju" like Abbas says in the video (0:31)
@@vigilantcork248 JeJuair is the name of the airline.
@@vigilantcork248 I'm sure you meant well, but rest assured, everybody understood it was Muan, not Jeju airport. In social media platforms, that habit of picking up on typos has really become unnecessary. Nobody is perfect, not everybody speaks english. Re-editing and re-uploading a video, absolutely not worth it if the error doesn't lead to some terrible and unforgivable misunderstanding..
The 737-800 Auxiliary Power Unit (APU) does not have an auto start function, however same aircraft do have this as an option.
How long it takes for apu to get GEN connected after start up?
Also, how long it takes to get 3 greens since alternate gear handles are pulled?
@@bobbrouzouf1932 About 45 seconds.
@@bobbrouzouf1932 Many minutes.
you never mentioned depressurisation of the craft upon impact with would cause explosion combined with heat..normally takes a few minutes to de-pressure.
The 737-800 is normally pressurized to 8,000 ft, below that altitude the pressure is increased to match that of the surrounding atmosphere. On landing the pressure differential would be almost zero and not contribute to the explosion.
🤓🥹
mechanical engineer? WTF you gon give overview on with your 1.8K subscribers??