Pilot Debrief

ARCTIC AIRCRAFT CO INC S 1B2 near Salcha, AK — 2017-05-27

Final reportANC17FA026
Sign in to save
Date
2017-05-27
Location
Salcha, AK, USA
Aircraft
ARCTIC AIRCRAFT CO INC S 1B2
Registration
N57AT
Category
Airplane
Highest injury
Fatal
Fatalities
2
Phase of flight
Maneuvering

Probable cause

The pilot's failure to maintain adequate airspeed while maneuvering in high winds, which resulted in the airplane exceeding its critical angle of attack and an aerodynamic stall. Contributing to the accident was the pilot's improper decision to load the airplane beyond its allowable gross weight and center of gravity limits.

Contributing factors

Contributing to the accident was the pilot's improper decision to load the airplane beyond its allowable gross weight and center of gravity limits.

NTSB narrative

The pilot and passenger were searching for an overdue boat with the intent of landing at a remote unimproved airstrip located near the boat's intended destination. A witness reported strong wind conditions as she observed the airplane circle the airstrip. While the airplane was circling, its nose suddenly dropped, and the airplane descended in a near-vertical attitude to ground impact. She stated that the engine continued to run, and the airplane did not make any unusual sounds, other than an increase in engine rpm, during the descent. A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The observed damage to the airplane indicated that it impacted the ground in a nose-down, near-vertical attitude. The witness account and the damage to the airplane were consistent with the pilot failing to maintain sufficient airspeed while maneuvering, which resulted in the airplane's wing exceeding its critical angle of attack and a subsequent aerodynamic stall. The airplane's estimated gross weight at the time of the accident was about 130.5 pounds over its approved maximum gross weight of 1,650 pounds, and the airplane's estimated center of gravity was about 0.1 inches beyond the approved aft limit at gross weight. As excessive weight increases stall speed and an aft center of gravity decreases controllability, it is likely that the pilot's decision to operate the airplane over gross weight with an aft center of gravity contributed to the loss of control.

Analysis

Primary failure mode
Loss of control
First missed decision gate
Pilot could have chosen not to circle the unimproved airstrip in strong winds.

NTSB coding

Evidence available

  • Photos
  • 8 docket documents
View NTSB final reportView NTSB docket

Docket documents8

Related mishaps