Pilot Debrief

CESSNA U206 near Rainy Pass, AK — 2018-09-24

Final reportCEN18FA386
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Date
2018-09-24
Location
Rainy Pass, AK, USA
Aircraft
CESSNA U206
Registration
N1738R
Category
Airplane
Highest injury
Fatal
Fatalities
1
Phase of flight
Approach

Probable cause

The pilot's improper decision to continue the flight in deteriorating weather conditions, which resulted in an inadvertent entry into a box canyon and subsequent controlled flight into mountainous terrain.

NTSB narrative

The airline transport pilot was flying the airplane to a remote lodge to deliver cargo and return with passengers. The pilot and the chief pilot, who was also following the same route about 16 minutes later, had monitored the weather before and during the flight and recognized that the clouds were present but believed they could make the flight. The flight track data showed that the pilot flew at low altitudes as he flew into a winding valley leading toward a mountain pass. The chief pilot stated that, based on radio calls from the pilot, he was maneuvering around low clouds. The flight track showed that the accident airplane continued toward the mountain pass, then proceeded south past two mountain passes and into a box canyon. The airplane impacted steep mountainous terrain facing north, consistent with the pilot attempting a steep right turn to reverse course and exit the box canyon. Aviation weather cameras near the accident location showed low clouds and precipitation around the time of the accident. The chief pilot continued toward the destination but then elected to turn around as the low clouds hindered him from navigating through the valley. It is likely that the accident pilot encountered deteriorating weather as he flew through the valley toward mountainous terrain and attempted to exit the box canyon but was unable to maintain clearance from terrain as he performed the steep right turn. A postaccident examination of the engine, airframe, and recorded engine data did not reveal any anomalies that would have precluded normal operation. Based on a review of the autopsy report and previous medical conditions, there was no evidence to suggest the pilot was impaired; therefore, the medical conditions were likely not a factor in this accident. Diphenhydramine was detected in the pilot's toxicology, but not quantified; therefore, the investigation was unable to determine if the pilot was impaired by diphenhydramine.

Analysis

Primary failure mode
VFR into IMC
First missed decision gate
Pilot could have turned back upon receiving weather updates indicating worsening conditions.

NTSB coding

Evidence available

  • ADS-B / radar
  • Photos
  • 22 docket documents
View NTSB final reportView NTSB docket

Docket documents22

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