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ASN Wikibase Occurrence # 146193
Last updated: 23 May 2019
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Date:07-JUN-2012
Time:12:35
Type:Silhouette image of generic PC12 model; specific model in this crash may look slightly different
Pilatus PC-12/47
Owner/operator:Roadside Ventures, L.L.C.
Registration: N950KA
C/n / msn: 730
Fatalities:Fatalities: 6 / Occupants: 6
Aircraft damage: Substantial
Category:Accident
Location:Polk County, FL -   United States of America
Phase: En route
Nature:Private
Departure airport:Fort Pierce, FL (FPR)
Destination airport:Junction City, KS (3JC)
Investigating agency: NTSB
Narrative:
The instrument-rated pilot activated the autopilot shortly after takeoff and proceeded in a west-northwesterly direction while climbing to the assigned altitude of flight level (FL) 260. Light-to-moderate icing conditions were forecast for the area; the forecast conditions were well within the airplane's capability, and the pilot of a nearby airplane reported only encountering light rime ice at the top of FL260. About 26 minutes 35 seconds after takeoff, the airplane's central advisory and warning system (CAWS) recorded activation of Pusher Ice Mode at FL247, consistent with pilot's activation of the propeller de-ice and inertial separator; the de-ice boots were not selected. Less than a minute after the activation of Pusher Ice Mode, an air traffic controller cleared the flight to deviate right of course due to adverse weather well ahead of the airplane. The airplane then turned right while on autopilot in instrument meteorological conditions (IMC) at FL251; about 4 seconds into the turn, with the airplane indicating about 109 knots indicated airspeed and in a right bank of less than 25 degrees, the autopilot disconnected for undetermined reasons. The pilot allowed the bank angle to increase, and about 13 seconds after the autopilot disconnected, and with the airplane descending in a right bank of about 50 degrees, the pilot began a test of the autopilot system, which subsequently passed. Recovered data and subsequent analysis indicate that the pilot allowed the bank angle to increase to a minimum of 75 degrees while descending; the maximum airspeed reached 338 knots. During the right descending turn, while about 15,511 feet and 338 knots (about 175 knots above maximum operating maneuvering speed), the pilot likely applied either abrupt or full aft elevator control input, resulting in overstress fracture of both wings in a positive direction. The separated section of right wing impacted and breached the fuselage, causing one passenger to be ejected from the airplane. Following the in-flight break-up, the airplane descended uncontrolled into an open field.

Examination of the separated structural components revealed no evidence of pre-existing cracks on any of the fracture surfaces. Postaccident examination of the primary flight controls and engine revealed no evidence of preimpact failure or malfunction. The flaps were found in the retracted position, and the landing gear was extended; it is likely that the pilot extended the landing gear during the descent. The horizontal stabilizer trim actuator was positioned in the green arc takeoff range, the impact-damaged aileron trim actuator was in the left-wing-nearly-full-down position, and the rudder trim actuator was full nose right. The as-found positions of the aileron, rudder trim, and landing gear were not the expected positions for cruise climb. Examination of the relays, trim switch, and rudder trim circuit revealed no evidence of preimpact failure or malfunction, and examination of the aileron trim relays and aileron trim circuit revealed no evidence of preimpact failure or malfunction; therefore, the reason for the as-found positions of the rudder and aileron trim could not be determined. Impact-related discrepancies with the autopilot flight computer precluded functional testing. The trim adapter passed all acceptance tests with the exception of the aural alert output, which would not have affected its proper operation. The CAWS log entries indicated no airframe or engine systems warnings or cautions before the airplane departed from controlled flight. A radar performance study indicated that the airplane did not enter an aerodynamic stall, and according to the CAWS log entries, there was no record that the stick pusher activated before the departure from controlled flight.

Before purchasing the airplane about 5 weeks earlier, the pilot had not logged any time as pilot-in-command in a turbopropeller-equipped airplane and had not logged any actual instrument flight time in the previous 7 years 4 months. Additionally, his last logged simulated instrument befor
Probable Cause: The failure of the pilot to maintain control of the airplane while climbing to cruise altitude in instrument meteorological conditions (IMC) following disconnect of the autopilot. The reason for the autopilot disconnect could not be determined during postaccident testing. Contributing to the accident was the pilot's lack of experience in high-performance, turbo-propeller airplanes and in IMC.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20120607X54234&key=1
https://flightaware.com/live/flight/N950KA


Revision history:

Date/timeContributorUpdates
07-Jun-2012 12:29 gerard57 Added
07-Jun-2012 12:32 gerard57 Updated [Time, Location, Source]
07-Jun-2012 13:06 Geno Updated [Time, Aircraft type, Registration, Cn, Operator, Location, Departure airport, Destination airport, Source, Narrative]
07-Jun-2012 14:13 Geno Updated [Time, Source]
07-Jun-2012 15:58 Geno Updated [Total fatalities, Total occupants, Source, Narrative]
07-Jun-2012 19:29 RobertMB Updated [Registration, Location, Source, Narrative]
19-Jun-2012 13:13 Geno Updated [Time, Source, Narrative]
06-Jul-2012 09:42 Geno Updated [Source]
01-Apr-2013 18:45 TB Updated [Location, Source, Narrative]
01-Apr-2013 19:02 TB Updated [Source]
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
27-Nov-2017 20:43 ASN Update Bot Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]

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