Aviation Accident Summaries

Aviation Accident Summary ANC20LA004

Goodnews Bay, AK, USA

Aircraft #1

N7721C

Piper PA32R

Analysis

The pilot was conducting the last segment of a scheduled visual flight rules (VFR) route to the company base airport with a pilot-rated observer on board. The weather conditions were night marginal VFR, and the departure airport was in a remote, dark area located on the edge of a large bay. The pilot stated that after takeoff to the east, while turning right to the northwest, he suddenly felt that the airplane was descending; he looked at the vertical speed indicator (VSI) and observed a 500 ft-per-minute descent. The airplane was about 500 ft above ground level at that time. He did not note abnormal engine indications or sounds and attempted to arrest the descent by pulling back on the control yoke, but nothing happened. The airplane impacted the water about 30 to 60 seconds later. He and the observer egressed with no injuries. The observer stated that after takeoff, he was adjusting his headlamp and not looking at the instruments or outside. He then saw what looked like heavy rain out the right window. He recalled that the engine sounded normal, and rpm sounded high just before the airplane “slammed” into the water, right wing first. He did not hear the pilot say anything about engine power or offer any warning to brace for impact. During an interview, the pilot stated that he believed that the airplane wasn’t producing sufficient power because the airplane continued to descend and had a negative VSI indication. He did not attempt to adjust the engine controls, perform any emergency procedures, prepare the airplane for a water landing, make a radio call, or activate the emergency locator transmitter because there was no time. He stated that he concentrated on flying straight ahead with the wings level and told the observer that they were going down. Photographs of the wreckage showed the right wing experienced significant fore-to-aft crush damage, the front fuselage was partially separated from the airframe, and the propeller blades were bent aft with spanwise torsional twists, indicative of engine power at impact. Based on the pilot’s statement that he did not observe abnormal engine indications or sounds, the observer’s recollection that the rpm sounded high before impact, and the propeller impact signatures, it is unlikely that the engine lost power. The pilot did not make sufficient corrections to prevent the impact, such as increasing rpm and throttle to maximum, performing restoring engine power procedures, or obtaining a landing attitude for ditching. Also, he stated that he pulled back on the yoke and the airplane did not respond, which would indicate an elevator control problem and not an engine problem. He made no radio call and did not activate the emergency locator transmitter before impact. Although the pilot indicated he concentrated on flying the airplane straight ahead with wings level, evidence is consistent with the airplane impacting the water in a nose-low, right-wing-down attitude. It is likely that the airplane impacted the water during the initial climbing turn phase, which was consistent with the observer’s recollection. The nearest weather observation about 4 minutes before the accident indicated an overcast cloud layer at 1,600 ft. The accident occurred about 1.5 hours after sunset and, according to the pilot and observer, the moonlight was obstructed by clouds. The pilot stated that it was very dark to the east, which was the direction the airplane was heading during the takeoff, initial climb, and the beginning of the right turn. He also recalled that there were some village lights in the distance to the west and that he did see a horizon. The dark night and lack of visual cues in the area were conducive to the effects of spatial disorientation and would have required an instrument scan to mitigate that hazard; however, based on the pilot’s statement, he was not monitoring the instruments until he felt that the airplane was descending. It is likely that the pilot experienced spatial disorientation during the right turn over dark terrain and water but did not recognize the descent as an indication of such and, therefore, did not correct by referencing the instruments and positively regaining control of the airplane.

Factual Information

On November 10, 2019, about 1840 Alaska standard time, a Piper PA-32-300 airplane, N7721C, sustained substantial damage when it was involved in an accident near Goodnews Bay, Alaska. The pilot and 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. The pilot was conducting the last segment of a scheduled flight route from Goodnews Airport (GNU), Goodnews, Alaska, to the company base at Bethel Airport (BET), Bethel, Alaska. The pilot invited a company pilot, who was undergoing initial training, to ride along as an observer in the right seat. The flight had no passengers, mail, or cargo on board. According to the pilot, after takeoff from runway 6 at GNU, the airplane climbed to about 300 ft above ground level, and he initiated a right turn to depart to the southwest avoid mountainous terrain to the north. He adjusted his engine control settings to 25 inches manifold pressure and 2,500 rpm and continued the turn to the northwest. The pilot recalled that it was dark but that he could see Beluga Point and Platinum village in the distance to the west and that a horizon was visible. During the turn, he 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 that the airplane was about 500 ft above ground level at that time. He rolled the airplane to a wings-level attitude. He attempted to arrest the rate of the descent by pulling back on the control yoke, but nothing happened. He did not observe abnormal engine indications or sounds and did not attempt to adjust any of the engine controls. He stated in an interview that he believed that the engine wasn't 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 the impact occurred about 30 to 60 seconds after the descent was first noted and stated that 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. He recalled that he told the observer that they were going down. The pilot-rated observer stated that after takeoff, he removed his headset to adjust his headlamp; he 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 started rushing into the airplane. 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 from his phone, and a Goodnews Bay search and rescue boat recovered the survivors within 15 minutes. He stated that, before the accident, he did not hear the pilot say anything about the engine power or preparing for impact and did not know they were in extremis until impact. The wreckage was not examined due to the remote location with limited access and the circumstances of the accident. A review of photographs of the wreckage indicated that the wings, fuselage, and right side of the stabilator sustained substantial damage. The engine and front fuselage were partially separated from the airframe at the firewall. The propeller blades were bent rearward with spanwise torsional twist signatures. The right wing exhibited significant fore-to-aft crush damage at the leading edge outboard wing section and upward deformation of the wing skin and main spar. The left outer wing section also exhibited crush damage at the outer section. A Garmin 796 GPS unit was recovered from the wreckage and sent to the National Transportation Safety Board’s Vehicle Recorder Laboratory for download. The data from the accident flight ended during a taxi sequence at GNU about 1858. It is likely that the data from the flight had not been recorded due to the unit’s buffering process. The airplane was not equipped with an automatic dependent surveillance-broadcast transponder. The pilot was night landing and instrument current at the time of the accident. The closest weather reporting facility was Platinum Airport (PTU), Platinum, Alaska, about 9 nautical miles southwest of the accident site. The 1856 observation, which was about 4 minutes before the accident, indicated wind from 140° at 12 knots gusting to 20 knots, 10 statute miles visibility, broken clouds at 1,600 ft, and overcast clouds at 2,000 ft. US Naval Observatory information indicated that sunset on the day of the accident was 1727, moonrise was 1739, and civil twilight ended at 1816. The pilot and observer reported that no moonlight was observed due to clouds. 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 position of the earth." This document lists factors contributing to spatial disorientation, including changes in angular acceleration, flight in instrument flight rules conditions, frequent transfer from visual flight rules to instrument flight rules conditions, and unperceived changes in aircraft attitude. This document concludes, "anytime there is low or no visual cue coming from outside of the aircraft, you are a candidate for spatial disorientation."

Probable Cause and Findings

The pilot’s failure to monitor the airplane instruments during a night visual flight rules departure in dark light conditions, which resulted in spatial disorientation and the airplane’s descent into water.

 

Source: NTSB Aviation Accident Database

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