Comment by gizmo686 11 hours 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.
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_...
If it costs too much it is also a bad idea. Why? Because that money can be spent on other safety.
If you're designing a new airport, sure, you can have runways with ample safety margins and generous overrun areas at the end of the runways. If you want to make an existing airport safer, and you can't buy up and demolish buildings around it, using EMAS is actually a cost-effective safety improvement.
Or a ramp with "one-way teeth" that stops it with gravity and stops it from sliding back down with teeth.
Sounds like a much more substantial runaway truck ramp
The solution is to "free" the perimeter of takeoff/landing. Bonus: People don't have to chose to work/live in these noisy areas. I understand some areas have challenges to come up with space but the US has tons of space and maybe the sea should be used to host these airports.
> 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
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.
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...
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_... [2] https://en.wikipedia.org/wiki/Southwest_Airlines_Flight_1248
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
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.
Rotation does increase drag, but you need to rotate in order to achieve the necessary angle of attack. The only way to reduce the rotation angle is by going faster than the normal rotation speed for the given weight and airfield density altitude, but doing so is out of the question in this scenario.
> 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/3m4tvh...
> 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.
There might be other kinds of damage where the quicker altitude gain of a normal rotation is crucial for survival.
I'm skeptical whether pilots can realistically make this kind of decision, given that they have no more than a few seconds to make it, and in cases such as this based on very incomplete information about the state of their aircraft.
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.
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.
> 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
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