A lot of them are designed to explode before hitting the target for maximum damage.

But yes, that's a lot of kinetic mass dead-stopping on a hard surface and 1 to 2 kiloliters of jet fuel.

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 fact that there was a fire long after the impact shows the fuel was not burnt in the crash. Fuel 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.

Some back-of-napkin math yields a crater depth of a little under a meter ... which is in the ballpark of images.

aircraft (1.5m radius cylinder x 18m long) at 6700kg = 51.54 kg/m3 aircraft density... over ~1,500kg/m3 average soil density x aircraft 18m length = 0.63m

=.63m / 2-foot penetration below ground level... which is what the pictures show.

Soil is dense. Aircraft are marshmallows compared to soil.

In the explosive sense, I agree. Depending on how much fuel they had, it could’ve been a decent percentage of the aircraft’s weight, though.

https://en.wikipedia.org/wiki/Impact_depth

When the object is near supersonic spèeds (throught the various materials) even the strenght of the materials becomes very secondary. A meteor made of sand makes the same crater as one made of stone.

IIRC some the guys who hijacked the planes took flying lessons and were notoriously uninterested in takeoff and landing compared to steering, according to their instructors. They weren't very sophisticate.

I'll give you the benefit of the doubt, though. In a conspirational mindset, if it was a false flag operation (and it did help USA find support to rearrange the Middle East oil control, get rid of their old bomb stock, and a few other perks), a State certainly has the proper people to plan such scheme, and the actual hijackers would only need to know which face and height of the towers to hit, and at what angle and speed.

I get that my comment probably didn't reach the "insightfulness" threshold for HN, but geez, go easy on me.

I'd guess that wasn't deliberate also, since logistically, it was better to hijack the plane while it was in range of their target, and it had enough fuel to make it look like kidnapping instead of terrorism to delay the response. One can't ignore that a refueled plane weighs about 20-25% more, though.

Citation: I'm a former airplane and missile guy.

At 30fps, I make that somewhere in the region of 1000mph.

Quite likely it exceeded that, some sensible numbers I've seen suggest between 800 to 1000 km/h final speed at impact

The actual VSI reading is taken either from barometric pressure or GNSS, and the source is flagged in a bit in the ADS-B packet. Then it's encoded in one of two forms in a 9-bit value with a single-bit sign.

If the 9-bit value is 0, there is no vertical speed available. Otherwise the vertical speed is encoded as +/-64 * (value - 1), giving a range from 0 to 510 for a range of bitfield values from 1 to 511.

Now this gives you a range in 64ft/min steps up to 32640ft/min. Most civilian high-performance aircraft will be in an absolutely screaming climb at around 10000ft/min and an 8000ft/min descent would be pretty aggressive - autopilots may drop into a 8000ish ft/min descent if there's a loss of cabin pressure, for example but 6000 would be considerably more comfortable. So even with your 9-bit value you've got enough resolution to show a fairly gentle climb (try staying below 1ft/sec climb or sink when flying by hand!) and something well in excess of what you'd normally want to experience.

64 * 511 = 32704

64 * 510 = 32640

So that's just a bunch of zeros for the lower bits.

Interesting. Thanks for the explanation.

If you're doing 32000ft/min you're clearly going *muuuuch* too fast, either up or down, implausibly so.

Unless you're in a jet fighter aircraft in which case showing up correctly on flightradar24 is not your biggest worry.

Let's not argue over the approximate nature of "1000mph" given the measurement constraints.

I think it's pretty much a mercy that no-one aboard would have felt a thing in the last couple of dozen milliseconds.

(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.)

Solves one problem, gives you a different problem...

I think your 1000 is the right ballpark but the units are wrong.

Sad story in this case. The cockpit audio was quite chilling.

https://www.pprune.org/accidents-close-calls/674728-lear-60-...

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).

https://en.wikipedia.org/wiki/Mach_tuck

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.

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."

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.

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

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"?

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.

The crater shows the road was destroyed. Aircraft skins are much thinner and less robust than road coverings.

Well, just looking at the article, I see trees, which tend to slow things down and can cause a plane to break up.

https://youtu.be/aSVfYwdGSsQ?t=132

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.

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.

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)

No pilot can fly a plane thats inside a truly violent thunderstorm. Flight control surfaces tend to snap off and in some cases the aircraft disintegrates in air. Some video suggests flight control surfaces broke off in flight here, which if accurate would explain the uncontrolled impact with the ground. The Lear Jet is a slick aircraft but one that has little margin for error.

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.

35,000 to 37,000 feet, combined with turbulence from the weather, means this could come into play. We still don't know and may not know for some time, especially given the severity of the impact and what may or may not have survived. But you can't rule it out.

[1]: https://aviationweek.com/business-aviation/learning-test-pil...

The descent rate seems the most likely cause of the missing stabilizer.

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.

Whatever the cause, it seems like climbing to avoid turbulence in or near thunderstorm conditions when the pilot knows there is ice already was probably unwise. A more prudent course was probably to divert around it and/or to descend to de-ice the plane. If so, would this rise to the level of pilot error? I don't know but maybe.

Im not sure how high the top of a thunderstorm can reach but if they could have gotten up and over the top above that 100%+ humidity before it had a chance to condense on the plane then i think that would have been the more prudent choice.

Generally in aviation more altitude is more safe. I think the only mistake was waiting too long to try and climb out of it rather than trying to climb over it to begin with. But im not a pilot so idk.

Staying away from thunderstorms is a good rule of thumb no matter the aircraft and crew capabilities. Severe turbulence is expected within 20 miles of the visible portion of a severe thunderstorm.

AIM 7-1-26 paragraph c is in all caps:

NO FLIGHT PATH THROUGH AN AREA OF STRONG OR VERY STRONG RADAR ECHOES SEPARATED BY 20-30 MILES OR LESS MAY BE CONSIDERED FREE OF SEVERE TURBULENCE.

AIM 7-1-27 can be summarized as stay the fuck away from thunderstorms. This entire section is dedicated to avoidance.

https://www.faa.gov/air_traffic/publications/atpubs/aim_html...

IANAP but the mention of precipitation points to conditions that could overwhelm anti-icing systems, which the Learjet was equipped with.

Highly recommend anyone reading to not make the same mistake

In every thread on this not a single person I have expressed anything other than regret for having heard it

I think the worst crash i learned about was when maintenance let a rear stabilizer go 20 years without so much as a checkup and the screw that controls the positioning of the rear stabilizer ran out of lube and stripped all the threads off mid flight causing the plane to lose all pitch control.

You could really hear the emotion in the pilots voice as they realized they were now riding a terrifying rollercoaster with no control over their altitude.

I actually think they may have survived which is insane, they had to try to control the pitch of the plane with the engine throttles, if you start going down then increase engines until you start going up again and if you go up to fast then decrease throttle.

Absolute insanity, i think they lived but if that had happened in the middle of a thunder storm while the plane was covered in ice there would be no chance.

The other incident with loss of rear stabilizer control was alaska airlines flight 261 and all 88 people on board died when the plane crashed in the pacific ocean.

> In every thread on this not a single person I have expressed anything other than regret for having heard it

That's because most people who don't feel the need to be overdramatic also don't need to feel the need to comment about it.

She goes from the confident pilot speak to panicked reports to starting to scream and hyperventilate, while doing her best to recover and communicate what's happening to the tower. At some point you hear them acknowledge that it's too late and they're all going to die. And then one last scream before suddenly cutting out.

It's just that gut-wrenching empathy and feeling of helplessness.

I would personally say that people should listen to this stuff, though. Life is hard and fragile, and even though it's hard, empathizing with this suffering makes sure we understand the real costs of our mistakes.

I saw way too many dismiss a million deaths by COVID. So many people bat their eyes at 100 people dying in a plane crash now. If they heard the recordings of these kinds of last moments, I think we'd be at less risk of our (moral/procedural) standards slipping.

2) Trump installed anti-aircraft missile launchers and radar at Mar-A-Lago just a few days ago.

3) The rear horizontal stabilizer appears to be missing from the highest quality dashcam ... and debris was found over 4 miles away from the crash site.

4) The size of the fireball does not seem commensurate with the amount of fuel that would be remaining for just 28 minutes left in the flight.

I am suspicious of the entire event.