N5163E

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 climbing to 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."