Accident Overview
On November 10, 2019, about 1840 Alaska standard time, a Piper PA-32-300 airplane, registration N7721C, sustained substantial damage when it impacted water near Goodnews Bay, Alaska. The pilot and a pilot-rated observer were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 nonrevenue segment of a scheduled commuter flight.
Flight Narrative
According to the pilot, the flight was the last segment of a scheduled route from Goodnews Airport (GNU) to the company base at Bethel Airport (BET). The pilot invited a company pilot undergoing initial training to ride as an observer in the right seat. The flight carried no passengers, mail, or cargo.
After takeoff from runway 6 at GNU, the airplane climbed to about 300 ft above ground level. The pilot initiated a right turn to depart to the southwest to avoid mountainous terrain to the north. He adjusted engine control settings to 25 inches of manifold pressure and 2,500 rpm and continued the turn to the northwest. The pilot recalled that it was dark, but he could see Beluga Point and Platinum village in the distance, and a horizon was visible.
During the turn, the pilot suddenly felt as if the airplane was descending. He looked at the vertical speed indicator (VSI), which indicated a 500 ft-per-minute rate of descent. He could not recall the airspeed and estimated the airplane was about 500 ft above ground level at that time. He rolled the airplane to a wings-level attitude and attempted to arrest the descent by pulling back on the control yoke, but nothing happened. He did not observe abnormal engine indications or sounds and did not adjust engine controls. He stated that he believed the engine was not producing sufficient power because the airplane “continued to descend unexplainably” and had “a negative VSI indication.”
The airplane impacted the water near the mouth of the Goodnews River, about 60 ft from the shoreline. The pilot estimated that impact occurred about 30 to 60 seconds after the descent was first noted. He stated there was no time to perform emergency procedures, attempt to restore power, make a radio call, activate the emergency locator transmitter, or prepare for a water landing. He concentrated on flying straight ahead with wings level and told the observer they were going down.
Observations
The pilot-rated observer stated that after takeoff, he removed his headset to adjust his headlamp and was not looking outside or at the instruments. After about 1-2 minutes of flight, he sensed something unusual and observed water outside the right window that he thought was heavy rain. He recalled that the engine sounded normal and that the rpm sounded high about 1-2 seconds before impact. The airplane then “slammed” into the water, right wing first. He did not know what the airplane hit until water rushed in. He heard the pilot exclaim, "get out, we have to get out!" The observer retrieved his waterproof mobile phone before egressing. Both occupants egressed out the right door and climbed on top of the fuselage, where the water level was between their knees and waist. The observer called for rescue, and a Goodnews Bay search and rescue boat recovered them within 15 minutes.
Wreckage and Data
The wreckage was not examined due to remote location and limited access. Photographs showed substantial damage to the wings, fuselage, and right side of the stabilator. The engine and front fuselage were partially separated at the firewall. Propeller blades were bent rearward with spanwise torsional twist. The right wing exhibited significant fore-to-aft crush damage at the leading edge outboard section and upward deformation of wing skin and main spar. The left outer wing section also showed crush damage.
A Garmin 796 GPS unit was recovered but data from the accident flight ended during a taxi sequence about 1858; it is likely the flight data was not recorded due to buffering. The airplane was not equipped with an ADS-B transponder.
Weather and Lighting Conditions
The closest weather reporting facility, Platinum Airport (PTU), about 9 nautical miles southwest, reported at 1856: wind from 140° at 12 knots gusting to 20 knots, 10 statute miles visibility, broken clouds at 1,600 ft, overcast at 2,000 ft. US Naval Observatory data indicated sunset at 1727, moonrise at 1739, and civil twilight ended at 1816. The pilot and observer reported no moonlight due to clouds.
Spatial Disorientation Background
The Federal Aviation Administration Civil Aerospace Medical Institute's publication "Introduction to Aviation Physiology" defines spatial disorientation as a loss of proper bearings; state of mental confusion as to position, location, or movement relative to the earth. Factors contributing to spatial disorientation include changes in angular acceleration, flight in instrument flight rules conditions, frequent transfer from visual to instrument conditions, and unperceived changes in aircraft attitude. The document states that anytime there is low or no visual cue from outside the aircraft, one is a candidate for spatial disorientation.