"No immediate reports of anyone on the ground injured or killed." If that's correct, the people in that silver car had the luckiest day of their lives.
The sound is just crazy and the images of the crash site seems somehow worse than what we've seen from e.g. Ukraine when a missile miss and slams into the ground.
The private jet carries up to 3.5 tons of fuel and weighs over 10 tons at take off. A Kalibr cruise missile is maximum 500kg of explosives and the heaviest variant is 2.3 tons over all.
Its not surprising at all that the jet makes a huge hole in the ground. Jet fuel is more energetic than RDX, while converting that energy slower. So both the chemical and kinetic energy is much higher with the jet then with a russian cruise missile. If anything the crater is surprisingly small.
The fuel would not have contributed to the crater. Fuel does not explode, not at the speed needed to form a crater. It requires oxygen. No matter how much fuel was present, there was not enough oxygen in the immediate vicinity of the crash to burn that much fuel.
The fact that there was a fire long after the impact shows the fuel was not burnt in the crash, that it hung around long enough to still be burning at least several seconds afterwards, long after the crater was formed. That is why it wasn't a missile. Missiles use high explosives (propellants and warheads) which burn up all at once to generally leave a non-burning crater.
A fully-fueled private jet is an inefficient missile, but it exceeds the raw chemical energy of most in-theater single-target tactical missiles (although the energy conversion is far less precise and efficient).
But yes, that's a lot of kinetic mass dead-stopping on a hard surface and 1 to 2 kiloliters of jet fuel.
Learjet 60 is about 18 metres long. In one frame it's a little above the ground, in the next it's gone up to about halfway between the cockpit glass and the wing roots, and in the next it's gone.
At 30fps, I make that somewhere in the region of 1000mph.
Last transmission was 22k feet/second, which is 15k mph.
(I thought ATC's cool as a cucumber 'altitude your discretion' was 'interesting' – presumably a formality they need to offer to clear the aircraft, since clearly no discretion was involved.)
Oops, thanks. Not familiar units for me, and I hadn't had a coffee.. that would be an absurd speed of course (nevermind to also have the composure to report it while experiencing it!).
It’s amazing to me that this post already feels quite old. But then I realized it only happened yesterday. I just feel that way because in today’s world we have seven different dashcam or security camera video feeds popping up on Reddit or X or whatever within minutes of a news event like this.
Sad story in this case. The cockpit audio was quite chilling.
No, throttle was surely idle. The plane was just flying vertically. In a dive, you have a 1:1 thrust/weight ratio and can go extremely fast. The pilot reported an overspeed warning on the audio (which people should not listen to if they're sensitive).
My gut says this is a sudden icing incident. Folks are pointing out that they appear to have flown straight into the center of a cell at altitude. A developing thunderstorm is MUCH warmer than the surrounding air, because the water condensing out of the rising/cooling mass buffers the temperature (due to heat of fusion). It can even be supersaturated ("higher than 100% humidity") if this happens fast enough. The water vapor is just desperate for a nucleation site to condense on.
So you have a situation where a metal jet body that is maybe 30C colder than the medium suddenly flies through this soup. It can ice over in seconds to minutes, and the plane ends up with bricks for wings and much more weight than it was designed for, and simply can't stay in the air. Then it dives inexorably.
It’s easy to get disoriented and accidentally accelerate into the ground, yes, (which is basically the procedure in a stall to get lift back anyway) but based on the ATC recording they knew what was going on and just dropped out of the sky.
The pilots were trying to save the plane up until the last moments. They declared an overspeed condition soon after they ran into trouble, so they were aware of it, but did not intentionally cause it.
And if they were so iced over that control surfaces weren't responding and the wings were no longer generating lift, at that point they were well past the "Anything we do is going to have any effect whatsoever on the future" point.
I don't intend to listen to the audio. Second-hand, it sounds as though they did absolutely everything they could after hitting the cell, and the only way to have avoided this whole situation was "Don't fly that route that day."
... a problem that, in general, we see more often in private-jet and single-engine aviation than commercial-carrier aviation. Far more incentives to make a really, really bad call... And when the bad call happens, the Venn diagram of victims and responsible parties tends to have a lot more overlap, so there's, practically speaking, fewer consequences to discourage such bad decisionmaking in the future (can't meaningfully punish the dead, and the dead can't learn from experience what a bad call "smells" like on the lead-up to it).
Forward velocity is proportional to lift, assuming your lifting surfaces still work. If you're stalling, standard practice is to apply power and get the nose down so that gravity and engine thrust are working in your favor to put air back under your wings.
In this case though, it sounds like the icing was much worse than they thought and fatally compromised the aerodynamics of the wings, and then the overspeed would have torn at the wings and fuselage... In that circumstance, you're no longer flying a plane, you're riding a javelin.
Training would generally still encourage the pilots to apply power; in the worst-case scenario (here), failing to apply power would not have made the crash survivably slower, so the sum total of best bad actions is still "Apply power and hope you're not in the worst-case scenario."
Reading what the pilot said is pretty harrowing. We know a lot from what the pilot already said over the radio (and maybe that's the best info we'll get, are there any remains left?)
Very little will be left considering the impact speed. Even if the aircraft was equipped with a flight data recorder (black box) then its structural limits were probably exceeded.
You would never know a plane caused that crater since there was so little left. Hopefully it puts to bed the conspiracy theories of the plane that crashed into the pentagon. Doubt it though.
If there is, seems they're deep under the ground as it nosedove straight into the ground and essentially disappeared, the crater showed almost no debris at all. People been guessing on reddit that everything just got "instantly pulverized" which I doubt somewhat, the shape of the frame is perfect for it shooting into the ground so I'm guessing they'll spend some weeks digging and eventually find the wreck.
Edit: Since I can't respond to my children:
> This kind of impact in fact has tendency to turn aircraft into powder
High-speed camera footage of rocket sleds and fuselage testing is fascinating stuff.
You can see the macroscopic deformation fail to transit the body of the impacting object with enough speed to make gross deformation happen as it collides. The front of the rocket body is literally turning to a vapor at the impact site, and the tail assembly is 100% fine.
Nerve impulses travel at about 120 m/s, max, and that's along long myelated runs. Cohering raw pain signal into the experience of pain takes at least 150 msec according to the best measurements we have on the topic.
The vertical speed of the plane alone at last reported speed indication exceeds the speed of neuron transmission along myelated nerve tissue. This impact event is mechanically impossible to feel.
> A similar crash that comes to mind ... where they did recover actual bodies, even if the impact was near-vertical and seemingly faster than this case.
Well, just looking at the article, I see trees, which tend to slow things down and can cause a plane to break up.
It's a tough listen and I don't begrudge your regret listening to it, however I think the pilot did a remarkable job of communication information about speed and bank angle right to the end which will indeed help this investigation and hopefully prevent future incidents.
The nice thing about all the tapes and recorders is that when you know you're completely fucked, you can be damn near assured that the last things you choose to say will be preserved. Whether you make it a last message to your family, or as many technical details as you can throw out that might help the investigation and keep someone else from dying the same way. In a way, documenting as much as you can of your impending death becomes your final task.
It's unclear exactly what happened but I've heard some aviation experts talk about this and there are already some leading theories, which come down to two factors:
1. The so-called coffin corner [1] where the minimum safe speed for aerodynamic lift and the speed where the plane will stall narrows to a dangerously narrow window. This is caused in part because the speed of sound decreases at high altitude. Turbulence can throw you out of this window; and
2. It seems likely that control was lost because of ice. In released ATC recordings (which are awful to listen to, be warned) the pilot mentions ice. This is likely because of the bad weather over south Florida right now.
The pilot requested a new flight path and I believe tried to ascend from 35,000 feet to 37,000 feet and ended up in a spiral, banked at ~60 degrees, descending at ~30,000 feet per minute, crashing into the ground.
I'm not a pilot but I suspect there will be some element of this that is pilot error or at least could've been avoided and/or mitigated by an experienced pilot.
There will be many questions on why the pilot flew into the tops of what (at least on radar) appeared as a small-ish localized cell at that altitude. Vertical cloud development at those altitudes is a clear sign that whatever is inside is not going to be pretty.
Once the aircraft entered the conditions inside the storm, between the turbulence, icing, and up/down drafts it was likely an unrecoverable event.
Icing was mentioned early in the ATC audio, then a request to increase altitude, then a comment that they encountered precipitation, implying the icing could get worse.
IANAP but the mention of precipitation points to conditions that could overwhelm anti-icing systems, which the Learjet was equipped with.
It wasn't coffin corner. This was a Lear at reasonable altitudes, not a U2 at the edge of space. The death spiral suggest a loss of control authority. It is conceivable that one wing severely iced to the point of unrecoverable asymmetric lift but I think it was something more the icing. It might have lost part of its wing, or the controls on one wing locked into an unrecoverable position.
In the pictures, the flaps appear present but not extended. If they had been extended they would have ripped away at that speed. And they would not have been able to lower them after the overspeed began. I think the answer is in the control system. One or more control surfaces were doing something other than commanded.
Some images seem to indicate a loss/absence of the horizontal stabilizer, but it is hard to tell AI from real these days.
That doesn't match what I'm seeing in the online discussions. I think most people who have a basic understanding of aviation or have been part of it would immediately see this as what happens when you fly a Learjet directly into a thunderstorm. The likely question is whether the first cause of loss of control was ice or something aerodynamic, like pushing the nose down in an updraft, causing the horizontal stabilizer to rip off.
In contrast, the coffin corner doesn't really have anything to do with this the plane would have been operating at standard enroute altitudes and speeds.
For context, I am in fact a pilot. I've read a little about what people are saying about this accident, but I've absolutely no new information or unique insight whatsoever.
It looked like a missile https://streamable.com/lg0on2
"No immediate reports of anyone on the ground injured or killed." If that's correct, the people in that silver car had the luckiest day of their lives.
The sound is just crazy and the images of the crash site seems somehow worse than what we've seen from e.g. Ukraine when a missile miss and slams into the ground.
> when a missile miss and slams into the ground.
A lot of them are designed to explode before hitting the target for maximum damage.
The private jet carries up to 3.5 tons of fuel and weighs over 10 tons at take off. A Kalibr cruise missile is maximum 500kg of explosives and the heaviest variant is 2.3 tons over all.
Its not surprising at all that the jet makes a huge hole in the ground. Jet fuel is more energetic than RDX, while converting that energy slower. So both the chemical and kinetic energy is much higher with the jet then with a russian cruise missile. If anything the crater is surprisingly small.
The fuel would not have contributed to the crater. Fuel does not explode, not at the speed needed to form a crater. It requires oxygen. No matter how much fuel was present, there was not enough oxygen in the immediate vicinity of the crash to burn that much fuel.
The fact that there was a fire long after the impact shows the fuel was not burnt in the crash, that it hung around long enough to still be burning at least several seconds afterwards, long after the crater was formed. That is why it wasn't a missile. Missiles use high explosives (propellants and warheads) which burn up all at once to generally leave a non-burning crater.
A fully-fueled private jet is an inefficient missile, but it exceeds the raw chemical energy of most in-theater single-target tactical missiles (although the energy conversion is far less precise and efficient).
But yes, that's a lot of kinetic mass dead-stopping on a hard surface and 1 to 2 kiloliters of jet fuel.
Technically called a wet explosion. Fuel deflagration, not explosive detonation.
Learjet 60 is about 18 metres long. In one frame it's a little above the ground, in the next it's gone up to about halfway between the cockpit glass and the wing roots, and in the next it's gone.
At 30fps, I make that somewhere in the region of 1000mph.
CBC article says vertical speed was 30,000 feet per minute, which is 550km/h or 150m/s.
it was also moving forward, not just downward.
Yes but that number is the vertical speed as it's measured in feet per minute.
The audio (don’t listen to it) has the pilot reporting the descent speed as 22,000 feet/min
I'm not planning on listening to it. I would expect that happened long before it hit the ground.
I’m not going to listen again to verify this but it felt like 20 seconds before they hit. The recording was only about a minute long.
Last transmission was 22k feet/second, which is 15k mph.
(I thought ATC's cool as a cucumber 'altitude your discretion' was 'interesting' – presumably a formality they need to offer to clear the aircraft, since clearly no discretion was involved.)
No it was feet per minute. 22,000 feet/second is almost orbital velocity.
Oops, thanks. Not familiar units for me, and I hadn't had a coffee.. that would be an absurd speed of course (nevermind to also have the composure to report it while experiencing it!).
there is dashcam footage from further away that gives a better indication of speed. It was fast but not supersonic.
There's a thread on pprune about this incident. The usual mix of informed and less-informed speculation.
https://www.pprune.org/accidents-close-calls/674728-lear-60-...
It’s amazing to me that this post already feels quite old. But then I realized it only happened yesterday. I just feel that way because in today’s world we have seven different dashcam or security camera video feeds popping up on Reddit or X or whatever within minutes of a news event like this.
Sad story in this case. The cockpit audio was quite chilling.
It's not even cockpit audio, it's just from ATC radio : - \
Don’t just crash. Was full throttle into the ground, by the looks of it.
No, throttle was surely idle. The plane was just flying vertically. In a dive, you have a 1:1 thrust/weight ratio and can go extremely fast. The pilot reported an overspeed warning on the audio (which people should not listen to if they're sensitive).
My gut says this is a sudden icing incident. Folks are pointing out that they appear to have flown straight into the center of a cell at altitude. A developing thunderstorm is MUCH warmer than the surrounding air, because the water condensing out of the rising/cooling mass buffers the temperature (due to heat of fusion). It can even be supersaturated ("higher than 100% humidity") if this happens fast enough. The water vapor is just desperate for a nucleation site to condense on.
So you have a situation where a metal jet body that is maybe 30C colder than the medium suddenly flies through this soup. It can ice over in seconds to minutes, and the plane ends up with bricks for wings and much more weight than it was designed for, and simply can't stay in the air. Then it dives inexorably.
Question from someone who knows nothing about aviation, is it possible that the pilot did that knowing they were doomed?
It’s easy to get disoriented and accidentally accelerate into the ground, yes, (which is basically the procedure in a stall to get lift back anyway) but based on the ATC recording they knew what was going on and just dropped out of the sky.
The pilots were trying to save the plane up until the last moments. They declared an overspeed condition soon after they ran into trouble, so they were aware of it, but did not intentionally cause it.
And if they were so iced over that control surfaces weren't responding and the wings were no longer generating lift, at that point they were well past the "Anything we do is going to have any effect whatsoever on the future" point.
I don't intend to listen to the audio. Second-hand, it sounds as though they did absolutely everything they could after hitting the cell, and the only way to have avoided this whole situation was "Don't fly that route that day."
... a problem that, in general, we see more often in private-jet and single-engine aviation than commercial-carrier aviation. Far more incentives to make a really, really bad call... And when the bad call happens, the Venn diagram of victims and responsible parties tends to have a lot more overlap, so there's, practically speaking, fewer consequences to discourage such bad decisionmaking in the future (can't meaningfully punish the dead, and the dead can't learn from experience what a bad call "smells" like on the lead-up to it).
Anything is is possible, but Mach tuck may have been an issue [1], but it slo may have been actual flight controls.
https://en.wikipedia.org/wiki/Mach_tuck
The italicised paragraph at the start of that article is not what I was expecting to read...
Forward velocity is proportional to lift, assuming your lifting surfaces still work. If you're stalling, standard practice is to apply power and get the nose down so that gravity and engine thrust are working in your favor to put air back under your wings.
In this case though, it sounds like the icing was much worse than they thought and fatally compromised the aerodynamics of the wings, and then the overspeed would have torn at the wings and fuselage... In that circumstance, you're no longer flying a plane, you're riding a javelin.
Training would generally still encourage the pilots to apply power; in the worst-case scenario (here), failing to apply power would not have made the crash survivably slower, so the sum total of best bad actions is still "Apply power and hope you're not in the worst-case scenario."
Reading what the pilot said is pretty harrowing. We know a lot from what the pilot already said over the radio (and maybe that's the best info we'll get, are there any remains left?)
Very little will be left considering the impact speed. Even if the aircraft was equipped with a flight data recorder (black box) then its structural limits were probably exceeded.
an SD card in foam in a thick metal sphere, like a bowling ball, would survive this, could be used as a backup to the main one.
The speculated final velocity at time of impact greatly exceeded design parameters for black box survivability so...
You would never know a plane caused that crater since there was so little left. Hopefully it puts to bed the conspiracy theories of the plane that crashed into the pentagon. Doubt it though.
Judging by what is circulating in Twitter today it mostly flared them up
> is there any remains left
If there is, seems they're deep under the ground as it nosedove straight into the ground and essentially disappeared, the crater showed almost no debris at all. People been guessing on reddit that everything just got "instantly pulverized" which I doubt somewhat, the shape of the frame is perfect for it shooting into the ground so I'm guessing they'll spend some weeks digging and eventually find the wreck.
Edit: Since I can't respond to my children:
> This kind of impact in fact has tendency to turn aircraft into powder
How often? A similar crash that comes to mind is https://www.washingtonpost.com/transportation/2023/06/05/dc-... where they did recover actual bodies, even if the impact was near-vertical and seemingly faster than this case.
What specific cases are you thinking about where everything "instantly pulverized"?
https://x.com/Nalanda_index/status/2117064398166777927
The crater shows the road was destroyed. Aircraft skins are much thinner and less robust than road coverings.
Mythbusters did this with a sled going "only" 650 mph and I would call the result instantly (but not entirely) pulverized:
https://youtu.be/aSVfYwdGSsQ?t=132
High-speed camera footage of rocket sleds and fuselage testing is fascinating stuff.
You can see the macroscopic deformation fail to transit the body of the impacting object with enough speed to make gross deformation happen as it collides. The front of the rocket body is literally turning to a vapor at the impact site, and the tail assembly is 100% fine.
This kind of impact in fact has tendency to turn aircraft into powder
Er, no. You’re greatly underestimating or misunderstanding the forces involved here. “Instantly pulverized” barely even begins to describe it.
In the video in the thread, it seems to go from fully extended airplane to pancake in about two frames, which is, again, harrowing, horrible.
It's basically airframe to dust in three frames, so maybe a 1/20th of a second. The moment of impact would have been mercifully quick.
Nerve impulses travel at about 120 m/s, max, and that's along long myelated runs. Cohering raw pain signal into the experience of pain takes at least 150 msec according to the best measurements we have on the topic.
The vertical speed of the plane alone at last reported speed indication exceeds the speed of neuron transmission along myelated nerve tissue. This impact event is mechanically impossible to feel.
> A similar crash that comes to mind ... where they did recover actual bodies, even if the impact was near-vertical and seemingly faster than this case.
Well, just looking at the article, I see trees, which tend to slow things down and can cause a plane to break up.
I regret listening to the audio. There is nothing gained by hearing it.
I have not and did not intend to, but you made me curious. Why should I not listen to it?
It's a tough listen and I don't begrudge your regret listening to it, however I think the pilot did a remarkable job of communication information about speed and bank angle right to the end which will indeed help this investigation and hopefully prevent future incidents.
The nice thing about all the tapes and recorders is that when you know you're completely fucked, you can be damn near assured that the last things you choose to say will be preserved. Whether you make it a last message to your family, or as many technical details as you can throw out that might help the investigation and keep someone else from dying the same way. In a way, documenting as much as you can of your impending death becomes your final task.
I always ignore warnings like this and am usually never affected by such audio but I feel psychologically scarred by it
Highly recommend anyone reading to not make the same mistake
Yep - some people are being paid to listen to that, but I'm not.
I don't want to be a naysayer, but what is this doing on HN?
It's unclear exactly what happened but I've heard some aviation experts talk about this and there are already some leading theories, which come down to two factors:
1. The so-called coffin corner [1] where the minimum safe speed for aerodynamic lift and the speed where the plane will stall narrows to a dangerously narrow window. This is caused in part because the speed of sound decreases at high altitude. Turbulence can throw you out of this window; and
2. It seems likely that control was lost because of ice. In released ATC recordings (which are awful to listen to, be warned) the pilot mentions ice. This is likely because of the bad weather over south Florida right now.
The pilot requested a new flight path and I believe tried to ascend from 35,000 feet to 37,000 feet and ended up in a spiral, banked at ~60 degrees, descending at ~30,000 feet per minute, crashing into the ground.
I'm not a pilot but I suspect there will be some element of this that is pilot error or at least could've been avoided and/or mitigated by an experienced pilot.
[1]: https://en.wikipedia.org/wiki/Coffin_corner_(aerodynamics)
There will be many questions on why the pilot flew into the tops of what (at least on radar) appeared as a small-ish localized cell at that altitude. Vertical cloud development at those altitudes is a clear sign that whatever is inside is not going to be pretty.
Once the aircraft entered the conditions inside the storm, between the turbulence, icing, and up/down drafts it was likely an unrecoverable event.
yeah but they could/would definitely break during the descent so you can't know if that was the cause or the effect
Icing was mentioned early in the ATC audio, then a request to increase altitude, then a comment that they encountered precipitation, implying the icing could get worse.
IANAP but the mention of precipitation points to conditions that could overwhelm anti-icing systems, which the Learjet was equipped with.
It wasn't coffin corner. This was a Lear at reasonable altitudes, not a U2 at the edge of space. The death spiral suggest a loss of control authority. It is conceivable that one wing severely iced to the point of unrecoverable asymmetric lift but I think it was something more the icing. It might have lost part of its wing, or the controls on one wing locked into an unrecoverable position.
In the pictures, the flaps appear present but not extended. If they had been extended they would have ripped away at that speed. And they would not have been able to lower them after the overspeed began. I think the answer is in the control system. One or more control surfaces were doing something other than commanded.
Some images seem to indicate a loss/absence of the horizontal stabilizer, but it is hard to tell AI from real these days.
That doesn't match what I'm seeing in the online discussions. I think most people who have a basic understanding of aviation or have been part of it would immediately see this as what happens when you fly a Learjet directly into a thunderstorm. The likely question is whether the first cause of loss of control was ice or something aerodynamic, like pushing the nose down in an updraft, causing the horizontal stabilizer to rip off.
In contrast, the coffin corner doesn't really have anything to do with this the plane would have been operating at standard enroute altitudes and speeds.
For context, I am in fact a pilot. I've read a little about what people are saying about this accident, but I've absolutely no new information or unique insight whatsoever.
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