6 ms·

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 ai

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 1y 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 1y 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 1y 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 1y 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 1y 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 1y 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 1y 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.

wickberg 1y 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 1y 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 1y 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 1y 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 1y 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 1y 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 1y 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.