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Comment by christophilus | Hacker News Reader

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.

Yep, the radio calls said something about -47C temp, them already fighting icing and “precipitation” ahead.

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.

How do you write to the sdcard while its packed in its foam helmet? If you put a little computer in there then it would have more mass and metal to smash around on impact. Maybe like a tiny usb card reader and a long data cable?

I wonder if running the data cable through the foam would cause problems like letting fire/fuel/water through the helmet and disolve/melt the plastics or if you whip a cable hard enough it can cut right through things like a weed wacker.

there are tiny chip size wireless receivers for small distances like this, you would need some sort of window through the metal, or a tiny antenna inserted through the ball shell and the wireless covers just the inside

or just ultra-thin wires connecting the memory to the outside. the ultra-thin wire will just snap and it's too light to cause damage by whipping around

the big problem is kinetic impact, fire/fuel/water would be easy to solve, for example fire requires oxygen which will have difficulties getting inside through a tiny hole, and I'm sure there is some metal alloy which doesn't melt in typical plane fuel fire temperatures

> 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.

> 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.

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.

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.

Unfortunately, even at a descent rate of 30,000 feet per minute you've got a full minute to anticipate the impact before you don't feel it.

This kind of impact in fact has tendency to turn aircraft into powder

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

Question from someone who knows nothing about aviation, is it possible that the pilot did that knowing they were doomed?

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).

I don't agree they had no way to avoid this. Every accident is a chain of mistakes, gaps or mechanical issues. We don't know the whole story here, but I do know that planes of this class are not given up for dead when they hit a surprise weather system. If they are, that means they missed something earlier - weather radar was misinterpreted or a bad judgment call was made.

That's my opinion given current information - only way to avoid this was to not put the plane in that storm.

Right - I misread your message. Yes they needed to avoid that storm and should have had chances to do so.

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.

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...

The Mach tuck recovery is counter intuitive, and could lead to further overspeed and forces exceeding design tolerances.

Another possibility is flutter. I read overspeed and icing mentioned by a pilot in the transcript. Therefore I think of those two elements conspiring in an edge case resulting in forces exceeding design limits, something broke, and made recovery impossible.

But anyway, the investigation will likely answer these questions.

agree. some other forums have alluded them losing their horizontal stabilizer (based off it not being in some stills of the plane crashing) - so the something broke case may also be a big element.

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