ANC19TA017

The pilot was conducting a visual flight rules (VFR) cross-country flight in marginal VFR conditions. While en route to his destination, he decided to maneuver off the intended course to surveil a mountainous area in the national park. While maneuvering in that area, he observed deteriorating weather. While he was looking down at the GPS display to confirm that he was navigating properly, the airplane entered instrument meteorological conditions (IMC). The pilot stated that he looked up and “probably” experienced spatial disorientation, so he commenced an instrument scan, confirmed that the wings were level, and started a right 180° turn to return to visual conditions. A review of GPS data indicated that the airplane was established on a relatively steady course about 600 ft above ground level, heading directly into higher terrain, then turned right for 50° and descended at a rate of about 520 ft per minute into terrain. The wreckage came to rest on the slope of a snow-covered ridge and was separated into sections along a 120-ft path, with signatures indicative of high-speed impact in a slight left-wing-low attitude. The fuselage, wings, and empennage sustained substantial damage. The weather forecast for the area indicated marginal VFR conditions, which was within the agency’s weather minimums. The pilot reported that while maneuvering to the ridgeline area, he noted “low” and “thick” clouds but felt comfortable because he was flying along the ridgeline that he recognized. A review of the pilot’s training records indicated that he was certified by his agency’s department for VFR-only flights and had no recent instrument flight experience. The agency had no instrument training or currency for reciprocating airplane pilots who were assigned to VFR flights. The pilot stated that he did receive simulated instrument training and was taught to turn back 180° for unintentional flight into IMC, although instrument training and inadvertent IMC were not documented on the annual check flight. Despite the forecast indicating marginal VFR conditions for the area, while en route, the pilot chose to divert from his planned route into an area of low cloud ceilings and rising terrain. The pilot inadvertently flew into the clouds, and by his own admission and the GPS data indicating an erratic flight profile, he likely experienced spatial disorientation, which resulted in the airplane’s descent into and impact with terrain. Contributing to the accident was the pilot’s lack of instrument proficiency which limited the skill required to perform the recovery technique while referencing only the instruments.

On April 15, 2019, about 0900 Alaska daylight time, a Cessna A185F airplane, N5163E, sustained substantial damage when it was involved in an accident near Nome, Alaska. The pilot sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 public aircraft flight. The pilot stated that the purpose of the flight was to fly from Ralph Wien Memorial Airport (PAOT), Kotzebue, Alaska, to Nome Airport (PAOM), Nome, Alaska (about 160 nautical miles), to pick up two National Park Service employees for transport. The pilot reported that he had flown the route from POAT to PAOM many times and was very familiar with the terrain along the route. He recalled that the graphical weather forecast for the area was for marginal visual flight rules (VFR) conditions; the weather forecast for PAOM was better than 1,900 ft ceiling and 10 statute miles of visibility. The pilot completed an operational risk assessment, filed a flight plan with the National Park Service Denali Dispatch, and departed PAOT about 0814. While en route, the pilot decided to fly over and surveil the Serpentine Hot Springs area, which was west of his planned flight route. He stated that he was flying about 1,600 ft mean sea level (msl), heading to the southwest, with a ridgeline close on the right side of the airplane. He observed a 500-ft warning from the terrain awareness and warning system on the Garmin GTN 750 GPS for the ridgeline on the right and noted also deteriorating weather conditions to the north. He observed “low” and “thick” cloud ceilings but felt comfortable because he was flying along a ridgeline that he recognized. He momentarily looked down at the GPS unit to check his navigation to the CIVID waypoint, and when he looked up, the airplane had entered instrument meteorological conditions (IMC). He stated that he felt disoriented and “probably” experienced spatial disorientation, so he immediately began an instrument scan and verified that the wings were level. In an attempt to return to visual meteorological conditions, he initiated a right 180° turn, momentarily forgetting that terrain was to the right, and the airplane immediately impacted snow-covered terrain. During the impact sequence, the left wing separated from the fuselage. The pilot recalled that he woke up inverted, secure in the seat restraint harness. He egressed the wreckage and observed heavy snowfall and wind. He sheltered inside the airplane until he was rescued about 1800 that day. A review of GPS data extracted from a Garmin GPSMAP 296 unit revealed that about 0858:37 (1 1/2 minutes before the accident), the airplane was flying at 1,358 ft msl (about 660 ft above ground level) along the south side of a river valley tracking about 250° +/- 7°, heading upriver in the direction of gently rising terrain. The airplane climbed to 1,424 ft msl, descended to 1,385 ft, climbed to 1,511 ft, descended to 1,409 ft, then climbed to 1,659 ft and turned right to 303° while climbingto 1,691 ft. The airplane then descended about 520 ft per minute into rising terrain and impacted a mountain slope about 1,552 ft msl at 0900:07. See figure 1. Figure 1. GPS track in 3D depiction on a Google Earth image with photograph of wreckage. (Source: Department of Interior Office of Aviation Services) The GPS data also revealed that the airplane was flying on a course into, and at an altitude below, an 1,800 ft ridge that was about 2,000 ft directly in front of the airplane before it turned right. The mountain was clearly marked on the VFR sectional chart. See figure 2. Figure 2. The GPS end of flight track with mountain elevations depicted and VFR sectional insert. The wreckage came to rest on the slope of a snow-covered ridge and was separated into sections along a 120-ft debris path to the northwest consistent with a high speed impact in forward flight. The propeller and left main landing gear were first in the path, followed by the separated left wing and then the inverted fuselage with the right wing and empennage attached. The fuselage, wings, and empennage sustained substantial damage. The Alaska Aviation Weather Unit issued a graphical flying weather forecast at 0400, current for the entire route of the flight, that indicated marginal VFR conditions. The pilot was certified by the Department of Interior’s Office of Aviation Services Alaska Region as a VFR-only pilot. He was instrument rated; however, he was not instrument current, nor was he required to be under Department of Interior guidance. The pilot stated that he obtained some IMC recovery training during annual flight training. He was taught to transition to an instrument scan, perform a course reversal for 180°, and “fly back out of it.”. Spatial Disorientation 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 IFR [instrument flight rules] conditions, frequent transfer from VFR to IFR 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."