PC 12 down in Nevada - 5 Fatalities

Wow. A pc-12 going down is pretty damn rare.
 
Anthem said:
Wow. A pc-12 going down is pretty damn rare.
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Recently, there was the one that tried to take off with the wings covered in ice and snow, and the one that plopped into a bay off of the east coast.
 
Ugh! The second multi-fatal crash in the same week. :(
 
Kenny Phillips said:
Looks like a 1500+ FPM descent that only stopped when it had to.
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Looks like just the 360 right spiral is at least 12000-13000 feet per minute, and another clip of the data seen elsewhere shows it probably reached considerably more than that.
 
TrueCourse said:
Looks like just the 360 right spiral is at least 12000-13000 feet per minute, and another clip of the data seen elsewhere shows it probably reached considerably more than that.
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Yeah, that's a crazy number. ADS-B isn't that good for this sort of calculations; the condition of the wreckage may tell the tale. Sad all around.
 
Can anyone tell me if this is true? Read online.

When the PC-12 was initially certified, it was unable to meet FAA certification requirements relating to control of the aircraft in certain flight conditions. Because of its hazardous stall characteristics, the PC-12 necessitated special approval of an anti-stall system to work around the FAA’s certification standard. This ‘work-around’ did not change the hazardous aerodynamic characteristics of the airplane, The PC-12 also has a history of problems in cold weather operations that affect the fuel system. This is a high-performance airplane which requires a high level of training and experience.​
 
Straight from the horse's mouth... https://pilatusowners.org/wp-content/uploads/2014/06/04fall.pdf

A good read.

"From the start the PC-12 could meet all stall requirements, indeed the stall characteristics of the PC-12 at low thrust coefficients were benign. However, with a power setting of 75% MCP the PC-12 stalls at a speed of 45 kcas, a pitch attitude in excess of 30º nose up. In this extreme condition the stall is finally characterized by a wing drop which at such low speed the ailerons do not have the authority to counteract."

Leonardo Manfriana
Chief Aerodynamicist

Tony Taylor
Head of Flight Test

Pilatus Aircraft, Ltd. P.O. Box #992 6371 Stans, Switzerland +41 41 619 64 25 www.pilatus-aircraft.com"​
 
Lycosaurus said:
Straight from the horse's mouth... https://pilatusowners.org/wp-content/uploads/2014/06/04fall.pdf

A good read.

"From the start the PC-12 could meet all stall requirements, indeed the stall characteristics of the PC-12 at low thrust coefficients were benign. However, with a power setting of 75% MCP the PC-12 stalls at a speed of 45 kcas, a pitch attitude in excess of 30º nose up. In this extreme condition the stall is finally characterized by a wing drop which at such low speed the ailerons do not have the authority to counteract."

Leonardo Manfriana
Chief Aerodynamicist

Tony Taylor
Head of Flight Test

Pilatus Aircraft, Ltd. P.O. Box #992 6371 Stans, Switzerland +41 41 619 64 25 www.pilatus-aircraft.com"​
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Thanks for the info!
 
John Spartan said:
Can anyone tell me if this is true?
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I wouldn't characterize it as a hazard more like a feature. They added a stick pusher and warning system and all is well from those I know who fly it regularly. As the PC12 has become more popular in AK I haven't heard of the fuel issue. For what the plane is capable of don't see where that would be an issue. I wonder if the Beechcraft Denali will require the same system as it seems to be a similar design.
 
Jeff Oslick said:
The principal flaw in the PC-12 might be that it is such a capable aircraft, it inspires pilots to do things that exceed the pilot's capabilities.
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Unfortunately there are other aircraft with similar "flaws." MU-2 comes to mind along with SPIFR Citations. Personally prefer the PC12 over everything else to ride in especially when off the beaten path.
 
well occam and I are on a first name basis. And just like the king air EMS crash a few months back in hawaii, this one "leans" like a duck too. It's all there to see. Icing doesn't give your aircraft the leans, spatial-D does. But we don't talk about fight club.
 
hindsight2020 said:
well occam and I are on a first name basis. And just like the king air EMS crash a few months back in hawaii, this one "leans" like a duck too. It's all there to see. Icing doesn't give your aircraft the leans, spatial-D does. But we don't talk about fight club.
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Late Night flight with what kind of weather I wonder. I had wondered if despite being FIKI capable (I assume) the pilot forgot to activate, accrued ice, realized late from distractions and here we are. But it’s all internet guesswork at this point.
 
John Spartan said:
Late Night flight with what kind of weather I wonder. I had wondered if despite being FIKI capable (I assume) the pilot forgot to activate, accrued ice, realized late from distractions and here we are. But it’s all internet guesswork at this point.
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The PC12 will truck a mountain of ice.
 
From the limited information provided by the photographs, it looks like the airplane was in a flat spin when it impacted.

From the Aviation Safety Network: "Sigmet for MOD Turbulence. Icing from ground to FL200. Light snow."

Here's a link to communications and ADS-B information during the short flight:


Looks like another weather-related tragedy.
 
https://globe.adsbexchange.com/?ica...e=2023-02-25&trackLabels&timestamp=1677302043

Note that there is a 4s gap in the data. I have kind of interpolated :)

Maybe notice that ADSB speeds are groundspeed and that an aircraft with a vertical trajectory has zero groundspeed.

Clicking on the aircraft position dots updates the left hand data panel.

Present position shows -32,000 ft per min (360 mph). No idea where this comes from, calculated at receiver or transmitted from aircraft instrument?

upload_2023-2-25_23-35-49.png
 
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hindsight2020 said:
well occam and I are on a first name basis. And just like the king air EMS crash a few months back in hawaii, this one "leans" like a duck too. It's all there to see. Icing doesn't give your aircraft the leans, spatial-D does. But we don't talk about fight club.
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Death spiral from 18,000 feet in a plane as well equipped as that? Hard for me to imagine. How does that happen?
 
Salty said:
Death spiral from 18,000 feet in a plane as well equipped as that? Hard for me to imagine. How does that happen?
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amazing plane. Hard to attest to the abilities of the pilot though. It only takes one off day.
 
From the photos they hit hard in an almost level altitude vertical descent. The fuse is flattened out and the vertical stab is snapped off.
 
John Spartan said:
amazing plane. Hard to attest to the abilities of the pilot though. It only takes one off day.
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What is amazing about it? From the context of your post I’m assuming you mean things such as redundancy and safety features rather than cargo door size and roominess.
 
Kritchlow said:
What is amazing about it? From the context of your post I’m assuming you mean things such as redundancy and safety features rather than cargo door size and roominess.
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would “awesome” work better? Turboprop power beast right? I was replying to the post saying it could carry a truckload of ice. My point was that this may be a pilot error issue in the end. So little it is all guesses at this point tho.
 
Salty said:
Death spiral from 18,000 feet in a plane as well equipped as that? Hard for me to imagine. How does that happen?
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The same way an identical sequence two months ago by another fixed wing EMS flight happened. The same way decked out airliners like Colgan 3407 happen; the way an even more decked out triple 7 almost happened (UA1722). Or the same way a .mil flight school classmate and personal acquaintance of mine darted a (admittedly legacy, aka non-gucci avionics) Hornet into the English countryside. Fight club. But we don't talk about fight club.

But by all means, let's instead spend time on the invariably incoming chastisement and NTSB appeal-to-authority fallacies which won't flesh out a scintilla of safety outcomes until circa my 9 year old's high school graduation. Let's instead devote time on the more complex and preposterous, but more emotionally convenient, theories about about icing, medical incapacitation, empennage spontaneous combustion, solar flares, chinese baroon evasive maneuvers gone wrong, or any other deus ex machinas people prefer in order to cope with the inability or unwillingness to digest fight club.
 
John Spartan said:
would “awesome” work better? Turboprop power beast right? I was replying to the post saying it could carry a truckload of ice. My point was that this may be a pilot error issue in the end. So little it is all guesses at this point tho.
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Well your post, IMO, said the crash couldn’t be an aircraft failure.
Perhaps I read too much into it.
 
Salty said:
Death spiral from 18,000 feet in a plane as well equipped as that? Hard for me to imagine. How does that happen?
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Turn rate suggests an average 60 to 65 degree bank angle during the 360° turn on the ADS-B track, steepening to over 70 degrees or more in the second half. High airspeed and descent rate does not suggest stall or spin. However, wings level, pitch level semi-intact wreckage does not seem to be consistent with the >10,000fpm descent rate.

The main danger of ice is the increase in stall speed, I can't think of a way it would cause a high-speed spiral dive.

My hypothesis: death spiral with a recovery initiated, but too low to be completed before hitting the ground. Possibly stalled during recovery attempt, but probably would have hit the ground either way.

These are completely made-up numbers but, at 20,000fpm, and a terrain elevation of 4,500', and a 16 second recovery time (6 seconds to roll out of the bank and 10 seconds to pitch up to arrest the descent), recovery would have to be initiated by 10,000' MSL.

edit: New information that a break up occurred before impact alters the hypothesis somewhat. No stall or spin at any point. Breakup occurred during the spiral dive caused by the high g-load, or caused by a high-g recovery attempt.
 
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dmspilot said:
The main danger of ice is the increase in stall speed, I can't think of a way it would cause a high-speed spiral dive.
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The PC12 has “pusher ice mode” which kicks on w/ the inertial separator open and prop deice on. I forget the exact particulars, but it significantly changes the AoA threshold at which the pusher activates.
 
DavidWhite said:
The PC12 has “pusher ice mode” which kicks on w/ the inertial separator open and prop deice on. I forget the exact particulars, but it significantly changes the AoA threshold at which the pusher activates.
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Even with the higher activation speed, I doubt the pusher was activated until after control was already lost, if it was activated at all.
 
dmspilot said:
Even with the higher activation speed, I doubt the pusher was activated until after control was already lost, if it was activated at all.
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Not disagreeing, just stating a point of fact with regards to the PC12s systems.
 
hindsight2020 said:
The same way an identical sequence two months ago by another fixed wing EMS flight happened. The same way decked out airliners like Colgan 3407 happen; the way an even more decked out triple 7 almost happened (UA1722). Or the same way a .mil flight school classmate and personal acquaintance of mine darted a (admittedly legacy, aka non-gucci avionics) Hornet into the English countryside.
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dmspilot said:
Turn rate suggests an average 60 to 65 degree bank angle during the 360° turn on the ADS-B track, steepening to over 70 degrees or more in the second half. High airspeed and descent rate does not suggest stall or spin. However, wings level, pitch level semi-intact wreckage does not seem to be consistent with the >10,000fpm descent rate.

The main danger of ice is the increase in stall speed, I can't think of a way it would cause a high-speed spiral dive.

My hypothesis: death spiral with a recovery initiated, but too low to be completed before hitting the ground. Possibly stalled during recovery attempt, but probably would have hit the ground either way.

These are completely made-up numbers but, at 20,000fpm, and a terrain elevation of 4,500', and a 16 second recovery time (6 seconds to roll out of the bank and 10 seconds to pitch up to arrest the descent), recovery would have to be initiated by 10,000' MSL.
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I’m not arguing that it was not a death spiral. I just don’t understand how that can happen.

AP is on and pilot is paying zero attention. Turbulence kicks off the A/P and it’s ignored?

If you’re looking anywhere near the instruments I don’t see how you can miss that a 60 degree bank is occurring.

It is frightening that things can go bad so quickly. If that track is accurate, 30 seconds from straight and level at FL180 to flat and dead on the ground.
 
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