What happened
On November 30, 2019, a Pilatus PC-12/47E, registration N56KJ, was involved in an accident near Chamberlain, South Dakota. The aircraft was operating as a private flight under Part 91 regulations. Prior to the accident, the pilot and passengers had stayed overnight at a local lodge. On the morning of the flight, the pilot and one passenger attempted to remove snow and ice from the aircraft using a ladder and isopropyl alcohol. While the wings were cleared, the pilot was unable to reach the top of the tail to clear the horizontal stabilizer.
At 1-24 hours prior to the accident, the area had experienced light to moderate snow and freezing drizzle. At 12:24 CST, the pilot requested an IFR clearance from Chamberlain Municipal Airport (9V9) to Idaho Falls Regional Airport (IDA). The pilot indicated a readiness to depart runway 31 within five minutes.
Data from the aircraft's Lightweight Data Recorder (LDR) shows the takeoff occurred at 12:31:58. The aircraft lifted off approximately 30 seconds later and immediately entered a left turn. During the initial climb, the airspeed fluctuated between 89 and 97 knots, but dropped to approximately 80 knots as the aircraft reached a peak altitude of 380 feet agl with a bank angle of 64 degrees. The stall warning and stick shaker activated one second after liftoff, followed by the stick pusher 15 seconds after liftoff. The aircraft entered a descent and impacted a dormant corn field approximately 3/4 mile west of the airport. The accident resulted in 9 fatal injuries and 3 serious injuries.
The investigation
An examination of the wreckage showed the engine had separated from the firewall and the left wing had separated at the root. Post-accident inspection of the airframe revealed no mechanical failures or malfunctions; engine parameters were consistent with rated takeoff power.
Weight and balance calculations determined the aircraft was approximately 107 lbs over its maximum gross weight. Furthermore, the center of gravity (CG) was located significantly beyond the aft limit. The aircraft was also carrying 12 occupants, despite having only 10 available seats, and none of the passengers qualified as lap children.
Flight simulations conducted by the NTSB indicated that the pilot's rotation technique—characterized by an abrupt and heavy pull on the control column—combined with the extreme aft CG and heavy weight, caused a high angle-of-attack immediately after rotation. This triggered the stall protection systems and led to pitch oscillations that eventually resulted in a deep aerodynamic stall and loss of control.