6 ms·

> they tried to take off instead of accelerate past the runway at ground level Do runways have some sort of barrier between them and the next "important" thing

by gizmo686 11mo ago

> they tried to take off instead of accelerate past the runway at ground level Do runways have some sort of barrier between them and the next "important" thing. It seems like that would be prudent both for cases like this, and breaking failures following landings.

octaane 11mo ago
Unless you have a berm several dozen meters high with a 100 meter base, you ain't stopping something like this from a physics standpoint unfortunately. Many airports have this problem. The recent korean air disaster which echos this is another example. BTW, this is why most airports, if possible, point out to sea...
- wickberg 11mo ago
  Newer airports usually try to have space, that's the only thing helping with the physics involved here. Older airports might have EMAS [1] retrofitted at the ends to help stop planes, but that's designed more for a landing plane not stopping quickly enough (like [2]) - not a plane trying to get airborne as in this case. [1] https://en.wikipedia.org/wiki/Engineered_materials_arrestor_system https://en.wikipedia.org/wiki/Engineered_materials_arrestor_... [2] https://en.wikipedia.org/wiki/Southwest_Airlines_Flight_1248 https://en.wikipedia.org/wiki/Southwest_Airlines_Flight_1248
- positron26 11mo ago
  There is a dead zone between rejection and successful take-off speeds. We see it hit too often. I think pilot training is playing a factor. A normal rotation kills too much energy. One engine can climb when you have some airspeed and get clean, but if you lose too much energy on rotation, the inefficiency of the AoA for the rest of the short flight means that engine can no longer buy you any up. I've seen too many single-engine planes going down while trying to pitch up the whole way down. So, less aggressive single-engine rotations and energy absorbers at the ends of runways that can't get longer. This seems like the kind of thing where we do it because it removes a significant cause of people dying. Just watched this angle a few more times: https://x.com/BNONews/status/1985845907191889930 https://x.com/BNONews/status/1985845907191889930 Another crash video shows the aircraft clearly descending before colliding with anything. It manages to go up a bit, so it's fast enough to get airborne. The normal looking rotation kills too much energy. The plane is then too inefficient to maintain speed. AoA goes up while energy goes down. Power available goes negative and then it's over.
  - bigbadfeline 11mo ago
    > It manages to go up a bit, so it's fast enough to get airborne. The normal looking rotation kills too much energy. Yes, it did get airborne for a few seconds but from the video below, it looks like the left wing was damaged by the fire and could not provide enough lift, then the right wing rolled the plane to the left causing the crash. https://bsky.app/profile/shipwreck75.bsky.social/post/3m4tvhsxt4s2i https://bsky.app/profile/shipwreck75.bsky.social/post/3m4tvh...
    - positron26 11mo ago
      > looks like the left wing was damaged by the fire The wings and aerodynamics don't really care if air or air with combustion are flowing around them. Roll is a consequence of the loss of control due to low speed and the yaw of the good engines. Speed up, rudder works, plane might maintain positive climb.
      - loeg 11mo ago
        > The wings and aerodynamics don't really care if air or air with combustion are flowing around them. Not saying it's what happened here, but if the heat is intense enough to deform the wing / control surfaces, it matters.
        positron26 11mo ago
        For skin, a few seconds might be significant. For the spars, not nearly enough time to matter. It's also not at cruise speed slamming into a downdraft or anything. This is about a 1G loading. Negligible for a while. While the fire looks cool, there's a lot of free stream mixing in and the temps won't really get that high beyond the cowling.
        SAI_Peregrinus 11mo ago
        More likely is the hydraulics on that side burst, leading to a loss of pressure keeping the control surfaces deployed. If that lead to the leading-edge slats retracting (like they did in AA 191) you'd get a massive loss of lift on that side. The structural parts of the wing didn't have time to melt, but the fire certainly could damage all the internal control materials.
deleted 11mo ago
[deleted]
topspin 11mo ago
> Do runways have some sort of barrier between them and the next "important" thing. Some do. Here is what it looks like when an overshooting plane utilizes such a barrier: https://www.youtube.com/watch?v=zW71FrX8t_g https://www.youtube.com/watch?v=zW71FrX8t_g 179 dead. Consider the possibility that gigantic flying aluminum tubes filled with tons of flammable fuel hurtling around at hundreds of kilometers per hour comprise a dilemma that has no trivial answers. Even defining what "important thing" means at any given instant is not straightforward.
- beAbU 11mo ago
  There is a spectrum between "no barrier" and "immovable barrier". Arrestor beds exist, and given enough space a fully loaded plane at take-off velocity can be stopped in a controlled and safe way. Cost and space are often the reason why this does not happen.
TylerE 11mo ago
Security/debris fencing yes, but that's like, orders of magnitude short of what would stop the amount of energy we're talking about here. You also don't particularly want it to be catastrophically effective as there are real world cases where planes have clipped the fence and then NOT gone on to crash, or at least to crash in a fairly controlled manner with the majority onboard surviving. Hitting a brick wall at 180mph is going to have a 0% survival rate.
- namibj 11mo ago
  Yet a reinforced concrete wall of e.g. triangular section and anchored with "long enough" piles would be about the only not-that-expensive way to turn a short strip of "airport land" past the EMAS into a V1 stopping supermarket.
FabHK 11mo ago
> Do runways have some sort of barrier between them and the next "important" thing. It seems like that would be prudent both for cases like this Ha, Jeju Air Flight 2216 smashed into a barrier on the second landing attempt in Muan last year [0], and people commented "How could there be a barrier at the end of the runway, so obviously stupid, irresponsible", etc. Now a plane does not smash into a barrier at the end of the runway and people suggest putting barriers at the end of the runway. Don't mean to attack parent post, but may I suggest that a) hordes of experts have thought long and hard about these issues, and it is unlikely that you can encounter this for the first time as a lay person and come up with a solution that has eluded the best engineers for decades ("why don't they attach a parachute to the plane?"), and b) we are very close to an optimum in commercial aviation, and there are few if any unambiguous ("Pareto") improvements, but rather just tradeoffs. For example: You leave cockpit doors open, terrorists come in and commandeer the plane to turn it into a weapon. You lock the cockpit doors closed, and suicidal pilots lock out the rest of the crew and commandeer the plane to turn it into a weapon of mass-murder-suicide. There are no easy answers. [0] https://en.wikipedia.org/wiki/Jeju_Air_Flight_2216 https://en.wikipedia.org/wiki/Jeju_Air_Flight_2216 ETA: In 2007 an A320 overran a runway in Brazil and crashed into a gas station, killing 187 pax & crew + 12 on the ground. https://en.wikipedia.org/wiki/TAM_Airlines_Flight_3054 https://en.wikipedia.org/wiki/TAM_Airlines_Flight_3054
- linehedonist 11mo ago
  One improvement is a bed of concrete at the end of the runway that will catch the wheels and slow an airplane down to a stop. Pretty much everyone agrees it’s a good idea but it’s not always possible due to space needs or cost. https://en.wikipedia.org/wiki/Engineered_materials_arrestor_system https://en.wikipedia.org/wiki/Engineered_materials_arrestor_...
  - hshdhdhehd 11mo ago
    If it costs too much it is also a bad idea. Why? Because that money can be spent on other safety.
    - 11mo ago
mannykannot 11mo ago
Some runways have been extended with ‘engineered materials’ surfaces, often a form of porous concrete into which an airliner’s wheels will sink, absorbing a lot of energy and arresting the airplane without causing it to break up. It is very effective for landing overruns, but I don’t know about last-seconds aborted takeoffs.
- loeg 11mo ago
  It's designed for the much lower speeds of landing overruns (70 knots and below), whereas takeoff speeds are higher (in this case, like 185 knots).

octaane 11mo ago

Unless you have a berm several dozen meters high with a 100 meter base, you ain't stopping something like this from a physics standpoint unfortunately. Many airports have this problem. The recent korean air disaster which echos this is another example. BTW, this is why most airports, if possible, point out to sea...

wickberg 11mo ago
Newer airports usually try to have space, that's the only thing helping with the physics involved here. Older airports might have EMAS [1] retrofitted at the ends to help stop planes, but that's designed more for a landing plane not stopping quickly enough (like [2]) - not a plane trying to get airborne as in this case. [1] https://en.wikipedia.org/wiki/Engineered_materials_arrestor_system https://en.wikipedia.org/wiki/Engineered_materials_arrestor_... [2] https://en.wikipedia.org/wiki/Southwest_Airlines_Flight_1248 https://en.wikipedia.org/wiki/Southwest_Airlines_Flight_1248
positron26 11mo ago
There is a dead zone between rejection and successful take-off speeds. We see it hit too often. I think pilot training is playing a factor. A normal rotation kills too much energy. One engine can climb when you have some airspeed and get clean, but if you lose too much energy on rotation, the inefficiency of the AoA for the rest of the short flight means that engine can no longer buy you any up. I've seen too many single-engine planes going down while trying to pitch up the whole way down. So, less aggressive single-engine rotations and energy absorbers at the ends of runways that can't get longer. This seems like the kind of thing where we do it because it removes a significant cause of people dying. Just watched this angle a few more times: https://x.com/BNONews/status/1985845907191889930 https://x.com/BNONews/status/1985845907191889930 Another crash video shows the aircraft clearly descending before colliding with anything. It manages to go up a bit, so it's fast enough to get airborne. The normal looking rotation kills too much energy. The plane is then too inefficient to maintain speed. AoA goes up while energy goes down. Power available goes negative and then it's over.
- bigbadfeline 11mo ago
  > It manages to go up a bit, so it's fast enough to get airborne. The normal looking rotation kills too much energy. Yes, it did get airborne for a few seconds but from the video below, it looks like the left wing was damaged by the fire and could not provide enough lift, then the right wing rolled the plane to the left causing the crash. https://bsky.app/profile/shipwreck75.bsky.social/post/3m4tvhsxt4s2i https://bsky.app/profile/shipwreck75.bsky.social/post/3m4tvh...
  - positron26 11mo ago
    > looks like the left wing was damaged by the fire The wings and aerodynamics don't really care if air or air with combustion are flowing around them. Roll is a consequence of the loss of control due to low speed and the yaw of the good engines. Speed up, rudder works, plane might maintain positive climb.
    - loeg 11mo ago
      > The wings and aerodynamics don't really care if air or air with combustion are flowing around them. Not saying it's what happened here, but if the heat is intense enough to deform the wing / control surfaces, it matters.
      - positron26 11mo ago
        For skin, a few seconds might be significant. For the spars, not nearly enough time to matter. It's also not at cruise speed slamming into a downdraft or anything. This is about a 1G loading. Negligible for a while. While the fire looks cool, there's a lot of free stream mixing in and the temps won't really get that high beyond the cowling.
        SAI_Peregrinus 11mo ago
        More likely is the hydraulics on that side burst, leading to a loss of pressure keeping the control surfaces deployed. If that lead to the leading-edge slats retracting (like they did in AA 191) you'd get a massive loss of lift on that side. The structural parts of the wing didn't have time to melt, but the fire certainly could damage all the internal control materials.

deleted 11mo ago

[deleted]

topspin 11mo ago

> Do runways have some sort of barrier between them and the next "important" thing. Some do. Here is what it looks like when an overshooting plane utilizes such a barrier: https://www.youtube.com/watch?v=zW71FrX8t_g https://www.youtube.com/watch?v=zW71FrX8t_g 179 dead. Consider the possibility that gigantic flying aluminum tubes filled with tons of flammable fuel hurtling around at hundreds of kilometers per hour comprise a dilemma that has no trivial answers. Even defining what "important thing" means at any given instant is not straightforward.

beAbU 11mo ago
There is a spectrum between "no barrier" and "immovable barrier". Arrestor beds exist, and given enough space a fully loaded plane at take-off velocity can be stopped in a controlled and safe way. Cost and space are often the reason why this does not happen.

TylerE 11mo ago

Security/debris fencing yes, but that's like, orders of magnitude short of what would stop the amount of energy we're talking about here. You also don't particularly want it to be catastrophically effective as there are real world cases where planes have clipped the fence and then NOT gone on to crash, or at least to crash in a fairly controlled manner with the majority onboard surviving. Hitting a brick wall at 180mph is going to have a 0% survival rate.

namibj 11mo ago
Yet a reinforced concrete wall of e.g. triangular section and anchored with "long enough" piles would be about the only not-that-expensive way to turn a short strip of "airport land" past the EMAS into a V1 stopping supermarket.

FabHK 11mo ago

> Do runways have some sort of barrier between them and the next "important" thing. It seems like that would be prudent both for cases like this Ha, Jeju Air Flight 2216 smashed into a barrier on the second landing attempt in Muan last year [0], and people commented "How could there be a barrier at the end of the runway, so obviously stupid, irresponsible", etc. Now a plane does not smash into a barrier at the end of the runway and people suggest putting barriers at the end of the runway. Don't mean to attack parent post, but may I suggest that a) hordes of experts have thought long and hard about these issues, and it is unlikely that you can encounter this for the first time as a lay person and come up with a solution that has eluded the best engineers for decades ("why don't they attach a parachute to the plane?"), and b) we are very close to an optimum in commercial aviation, and there are few if any unambiguous ("Pareto") improvements, but rather just tradeoffs. For example: You leave cockpit doors open, terrorists come in and commandeer the plane to turn it into a weapon. You lock the cockpit doors closed, and suicidal pilots lock out the rest of the crew and commandeer the plane to turn it into a weapon of mass-murder-suicide. There are no easy answers. [0] https://en.wikipedia.org/wiki/Jeju_Air_Flight_2216 https://en.wikipedia.org/wiki/Jeju_Air_Flight_2216 ETA: In 2007 an A320 overran a runway in Brazil and crashed into a gas station, killing 187 pax & crew + 12 on the ground. https://en.wikipedia.org/wiki/TAM_Airlines_Flight_3054 https://en.wikipedia.org/wiki/TAM_Airlines_Flight_3054

linehedonist 11mo ago
One improvement is a bed of concrete at the end of the runway that will catch the wheels and slow an airplane down to a stop. Pretty much everyone agrees it’s a good idea but it’s not always possible due to space needs or cost. https://en.wikipedia.org/wiki/Engineered_materials_arrestor_system https://en.wikipedia.org/wiki/Engineered_materials_arrestor_...
- hshdhdhehd 11mo ago
  If it costs too much it is also a bad idea. Why? Because that money can be spent on other safety.
  - 11mo ago

mannykannot 11mo ago

Some runways have been extended with ‘engineered materials’ surfaces, often a form of porous concrete into which an airliner’s wheels will sink, absorbing a lot of energy and arresting the airplane without causing it to break up. It is very effective for landing overruns, but I don’t know about last-seconds aborted takeoffs.

loeg 11mo ago
It's designed for the much lower speeds of landing overruns (70 knots and below), whereas takeoff speeds are higher (in this case, like 185 knots).