Loss of control Accident Cessna 337F Super Skymaster N337V,
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ASN Wikibase Occurrence # 238861
 
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Date:Thursday 30 July 2020
Time:08:38 LT
Type:Silhouette image of generic C337 model; specific model in this crash may look slightly different    
Cessna 337F Super Skymaster
Owner/operator:private
Registration: N337V
MSN: 33701369
Year of manufacture:1971
Total airframe hrs:2028 hours
Engine model:Continental TSIO-360-C
Fatalities:Fatalities: 1 / Occupants: 3
Aircraft damage: Substantial
Category:Accident
Location:Ennis, Madison Range, Madison County, MT -   United States of America
Phase: En route
Nature:Private
Departure airport:Helena Airport, MT (HLN/KHLN)
Destination airport:Jackson Hole Airport, WY (JAC/KJAC)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The left seat pilot-in-command (PIC) reported that, he passed the controls to the right seat student pilot once they were en route on the accident flight. The rear seat passenger's postaccident statement indicated that the left seat pilot was at the controls for the duration of the flight; however, he may not have seen the exchange of the flight controls as he was seated behind both pilots at the time. As they were flying southbound on the cross-country flight over a valley about 3,000 ft above ground level, they agreed that they wanted to view a resort in the area. The student pilot then turned the airplane to the southeast towards higher mountainous terrain. After the airplane had entered a boxed canyon, and with a ridge in the airplane's flightpath that it could not clear, the PIC took control of the airplane and attempted an evasive maneuver to reverse course to exit the canyon. However, during the maneuver, the PIC likely did not maintain sufficient airspeed, which resulted in an aerodynamic stall/spin and subsequent impact with remote mountainous terrain. The PIC reported no mechanical anomalies with the airplane that would have precluded normal operation.

Toxicology results indicated that the student pilot had used cannabis, but likely had metabolized it such that no detectable psychoactive chemicals remained in his blood. The toxicology results and the student pilot's limited role in the accident flight suggest that the effects of cannabis use were unlikely to have contributed to the accident.

Probable Cause: The pilot-in-command's failure to maintain sufficient airspeed while attempting an evasive maneuver from a boxed canyon, which resulted in an aerodynamic stall/spin and impact with mountainous terrain. Contributing to the accident was the pilot-in-command's failure to monitor the environment before flying into mountainous terrain.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: WPR20LA245
Status: Investigation completed
Duration: 1 year and 10 months
Download report: Final report

Sources:

NTSB WPR20LA245
FAA register: https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=337V

History of this aircraft

Other occurrences involving this aircraft
20 April 2001 N20AK Private 0 Quinton, VA sub

Location

Revision history:

Date/timeContributorUpdates
30-Jul-2020 22:43 Geno Added
31-Jul-2020 01:27 Geno Updated [Time, Total fatalities, Location, Source, Damage, Narrative]
31-Jul-2020 02:06 RobertMB Updated [Operator, Nature, Departure airport, Destination airport, Damage, Narrative]
31-Jul-2020 02:18 RobertMB Updated [Location, Source, Narrative]
31-Jul-2020 06:33 harro Updated [Aircraft type]
31-Jul-2020 14:10 harro Updated [Registration, Cn, Operator, Source]
01-Aug-2020 05:55 Geno Updated [Source]
01-Aug-2020 12:14 Captain Adam Updated [Location, Narrative]
27-Jun-2021 07:55 aaronwk Updated [Time, Source, Narrative, Category]
11-Jun-2022 12:01 Aerossurance Updated [Source]
24-Jun-2022 14:33 ASN Update Bot Updated [Time, Operator, Total fatalities, Other fatalities, Source, Damage, Narrative, Accident report]
24-Jun-2022 14:40 harro Updated [Operator, Total fatalities, Other fatalities, Source, Narrative]

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