- Location: Recluse, Wyoming
- Accident Number: WPR24FA257
- Date & Time: July 26, 2024, 13:04 Local
- Registration: N357HE
- Aircraft: PILATUS AIRCRAFT LTD PC12/47E
- Aircraft Damage: Destroyed
- Defining Event: Loss of control in flight
- Injuries: 7 Fatal
- Flight Conducted Under: Part 91: General aviation - Personal
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On July 26, 2024, about 1304 MDT, a Pilatus Aircraft LTD, PC-12/47E airplane, N357HE, was destroyed when it was involved in an accident near Recluse, Wyoming. The pilot and six passengers were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
The pilot and six passengers departed on a cross-country flight on an instrument flight rules (IFR) flight plan with a planned refueling stop in Montana. The airplane flew on a northwest course consistent with its planned destination. The airplane leveled off at a maximum cruise altitude of about 26,000 ft mean sea level (msl).
Satellite imagery indicated that, at the accident site about the time of the accident, cumulus cloud bases were about 10,000 ft msl with rain showers; and the cloud tops were about 28,500 ft msl. The sounding model indicated trace to light icing with a low probability of supercooled large droplets (SLD) along about the last 20 minutes of the airplane’s flight path. The accident airplane was equipped for flight into known icing conditions and likely would not accumulate much, if any, structural icing from trace to light icing. Additionally, SLDs were likely not a factor given their low probability of occurrence and the flight profile of the accident airplane during the last few minutes of flight.
During the last portion of the flight, about 15 seconds before the airplane entered an area of precipitation as depicted by weather reflectivity charts, the pilot reported a loss of the autopilot and declared an emergency to the air route traffic control center controller. The controller asked the pilot where he would like to land and the pilot responded that he was trying to get control of the airplane; the controller told the pilot to advise if he required additional assistance. The controller then relayed the minimum IFR altitude and current altimeter setting with no further response from the pilot.
Data indicate that shortly after entering the area of precipitation, the airplane maneuvered to the right of course, climbed to about 26,525 ft msl, and entered a 270° right turn. In the first 180° of the turn, the airplane descended to about 25,250 ft msl; however, it climbed to about 27,025 ft msl in the last 90° of the turn. Shortly after, the data showed the airplane made a slight left turn before it began a descending 180° right turn. The last data point showed the airplane on a southerly heading, at an altitude of about 21,900 ft msl, and with a groundspeed of 256 knots.
Sound modeling data indicate that rain shower or thunderstorm activity had the potential for an updraft speed of up to 3,346 ft/min. ADS-B data indicated that the autopilot disconnected a few seconds after the airplane encountered the precipitation, likely when the airplane encountered an updraft because the autopilot was unable to counteract an updraft of the strength indicated by the modeling data. The airplane was likely operating in instrument meteorological conditions (IMC) throughout the remainder of the flight.
Following the autopilot disengagement, the pilot had to manually maintain control of the airplane while operating in IMC, increasing his susceptibility to spatial disorientation. The airplane’s erratic flight track in the final 2 minutes of flight, culminating in the final rapidly descending right turn, were consistent with the known effects of spatial disorientation. Furthermore, the pilot’s focus to re-engage the autopilot likely created an operational distraction that contributed to a breakdown in his instrument scan.
The airplane likely partially broke up at low altitude during its rapid descent to the ground, consistent with an exceedance of the airplane’s maximum operating speed. Pieces of the left wing were found up to 0.82 miles from the main wreckage and exhibited signatures of overload.
Impact signatures at the accident site, witness observations, and review of the flight data were all consistent with the pilot losing control of the airplane. Furthermore, postaccident examination of the airplane wreckage revealed no evidence of preimpact failures or malfunctions that would have precluded normal operation. Specifically, while the airplane sustained significant impact damage, the portions of the flight control system that could be examined showed no evidence of disconnections or preimpact failures. In addition, the airplane’s setting for the pitch trim was near neutral and for the roll trim was slightly right wing down.
- Probable Cause: The pilot’s loss of control due to spatial disorientation while operating in instrument meteorological conditions, which resulted in an in-flight breakup. Contributing to the accident was the pilot’s distraction from the autopilot disconnecting due to an updraft from convective activity.
Pilot Information
The private pilot held ratings for airplane single-engine land, multi-engine land, and an instrument rating. The pilot was issued an FAA third-class airman medical certificate on September 15, 2022, with the following limitation: must have available glasses for near vision. The pilot reported on his most recent application that he had accumulated 2,200 total hours of flight experience, with 70 hours in the 6 months before the examination.
The pilot successfully completed recurrent Pilatus PC-12NG training at the Recurrent Pilot Training Center on February 6, 2024. Included in the training was unusual attitude recovery.
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