PC-12 Crash In South Dakota, 9 dead, 3 survivors (CFIBlizzard?)

[MauleSkinner]

There is for some reason in the PC12 community a large amount of instructors who teach this “technique”. I believe the fascination lies in treating the PC12 like a jet, which it is not.

This is also not proper technique for a jet, so most likely they’re just trying to compensate for other poor technique.

 

[DavidWhite]

This is also not proper technique for a jet, so most likely they’re just trying to compensate for other poor technique.

The command bars are set for a single-engine go-around (or so they say) on the one I fly. 12 degrees. The PC12s bars go to (IIRC) 9 or 10 degrees which you will not be able to get to on a GWTO or hot and high day.

I was taught to pitch for the command bars until 200 knots, and then maintain 200 until above 2500agl and accelerate to 250 unless speed limited by a sid. Not saying thats the correct technique, but it is the one I was taught.

 

[woodchucker]

You would think a few passengers would of spoke up & said, ‘he77 no, I ain’t getting in that plane with these conditions’. Like a survival instinct kicking in.

Herd mentality. And this was a hunting group. Who amongst them would say "I'm gonna stay here and wait for a better day" verbally out loud when they probably have survived worse conditions out in the wild with no issues ... but they are not aviation knowledgeable. I'm sure at least some were praying internally but group think is a heck of a drug.

 

[3393RP]

An airplane performance analysis indicated that the accumulated snow and ice on the empennage did not significantly degrade the airplane performance after takeoff.

Flight recorder data revealed that the accident pilot tended to rotate more rapidly and to a higher pitch angle during takeoff than a second pilot who flew the airplane regularly. Piloted simulations suggested that the accident pilot’s rotation technique, which involved a relatively abrupt and heavy pull on the control column, when combined with the extreme aft CG, heavy weight, and early rotation on the accident takeoff, contributed to the airplane’s high angle-of attack immediately after rotation, the triggering of the stick shaker and stick pusher, and the pilot’s pitch control difficulties after liftoff. The resulting pitch oscillations eventually resulted in a deep penetration into the aerodynamic stall region and subsequent loss of control.

I disagree with your conclusion that accumulated ice and snow was not a causal factor in the crash. The presence of that much contamination and its weight (see the photos in the docket) would almost certainly alter the elevator pitch effectiveness and amplify pilot inputs. The NTSB did not fully consider this aspect.

You also glossed over the fact that because the inertial ice seperator was active and the boots were in cycling mode, it placed the flight computer in "ice pusher" mode, which increased the target airspeed for rotation and other v speeds, and engaged the stick shaker and pusher at lower airspeeds than normal. The stick shaker activated immediately upon rotation, and the pusher shortly thereafter. Aural stall warnings were almost continuous during the short time the aircraft was in the air. These actions began occurring before the pilot's pitch inputs.

There's no doubt the pilot's inputs exacerbated the oscillations, but his inattention to or ignorance of the changed v speeds ensured the aircraft would not be controllable at rotation, absent instant recognition of the situation and strict discipline in attaining proper pitch and speed targets. I discount the fact that a simulator recreation of the flight produced a different outcome.

 

[ServoB17]

I'm sure at least some were praying internally but group think is a heck of a drug.

One of them was praying externally:

CAM-?
[passenger recites traveler's prayer] ** our Father in
heaven we're grateful that we've been able to come out
here to South Dakota and have a wonderful time with
family we appreciate the blessings that we enjoy and
we're thankful that we can be together on this
Thanksgiving weekend we appreciate everything that
God does for us especially providing us a savior and
we appreciate Him very much. Father in Heaven we
ask for a special blessing now that we take off in this
not so great weather and that (Thy) will watch over and
protect us. impress upon the mind of @ [pilot] that he
might know how best to travel this course that we are
about to do and we are thankful for this airplane and
ask that You will watch over and protect us. *** (ensure
the function of this aircraft) we say this in the name of
Jesus Christ amen.

https://data.ntsb.gov/Docket/Docume...ileName=CEN20FA022_CVR_Report_RELEASE-Rel.pdf

 

[Dave Theisen]

The command bars are set for a single-engine go-around (or so they say) on the one I fly. 12 degrees. The PC12s bars go to (IIRC) 9 or 10 degrees which you will not be able to get to on a GWTO or hot and high day.

I was taught to pitch for the command bars until 200 knots, and then maintain 200 until above 2500agl and accelerate to 250 unless speed limited by a sid. Not saying thats the correct technique, but it is the one I was taught.

250? I guess the ones you fly are a lot faster than the ones I fly, and even faster than Pilatus says to fly them.

 

[DavidWhite]

250? I guess the ones you fly are a lot faster than the ones I fly, and even faster than Pilatus says to fly them.

Sorry, I should have specified that was referring to the speeds I fly the jet (LR45) at. I usually climb the PC12 around 140 as it seems pretty happy there.

 

[steingar]

This would be, if a true statement by the deceased, a personal interpretation of the Church doctrine. The Church of Jesus Christ of Latter Day Saints has no such formal doctrine. People are quite free to interpret how they honor the Sabbath day, with only very loose guidelines. They may have wished to be back in time for Church, and may have had responsibilities that they felt they needed to honor. But no restriction on flying or traveling. Very sad event, and a very generous and charitable family devastated.

I hate to break it to you, but the Sabbath is on Saturday. If you don't believe me have a look at your calendar.

I suppose this is the week I should have given up being persnickety. Gave up alcohol already.

 

[woxof]

I disagree with your conclusion that accumulated ice and snow was not a causal factor in the crash. The presence of that much contamination and its weight (see the photos in the docket) would almost certainly alter the elevator pitch effectiveness and amplify pilot inputs. The NTSB did not fully consider this aspect.

You also glossed over the fact that because the inertial ice seperator was active and the boots were in cycling mode, it placed the flight computer in "ice pusher" mode, which increased the target airspeed for rotation and other v speeds, and engaged the stick shaker and pusher at lower airspeeds than normal. The stick shaker activated immediately upon rotation, and the pusher shortly thereafter. Aural stall warnings were almost continuous during the short time the aircraft was in the air. These actions began occurring before the pilot's pitch inputs.

There's no doubt the pilot's inputs exacerbated the oscillations, but his inattention to or ignorance of the changed v speeds ensured the aircraft would not be controllable at rotation, absent instant recognition of the situation and strict discipline in attaining proper pitch and speed targets. I discount the fact that a simulator recreation of the flight produced a different outcome.

Sorry for the error I made in not putting quotation marks from the report to show that these are the words of the NTSB. I glossed over nothing, just quoting the NTSB final report.

 

[Dave Theisen]

You also glossed over the fact that because the inertial ice seperator was active and the boots were in cycling mode, it placed the flight computer in "ice pusher" mode, which increased the target airspeed for rotation and other v speeds, and engaged the stick shaker and pusher at lower airspeeds than normal. The stick shaker activated immediately upon rotation, and the pusher shortly thereafter. Aural stall warnings were almost continuous during the short time the aircraft was in the air. These actions began occurring before the pilot's pitch inputs.

There's no doubt the pilot's inputs exacerbated the oscillations, but his inattention to or ignorance of the changed v speeds ensured the aircraft would not be controllable at rotation, absent instant recognition of the situation and strict discipline in attaining proper pitch and speed targets. I discount the fact that a simulator recreation of the flight produced a different outcome.

Just so the facts are straight, the boots have nothing to do with pusher ice mode, it is the combination of the inertial separator being open and the prop de-ice turned on that recalibrates the pusher.