ANC22LA025 · Cessna 172P

The airplane departed on a visual-flight-rules flight to conduct a routine hurricane/tsunami warning mission. The standard flight route was to fly inland, passing a radar dome before turning west toward the coast. The airplane was then to fly offshore, following the coastline around the island. Automatic Dependent Surveillance–Broadcast (ADS–B) data showed the airplane never made the turn to the coast and it continued over land and up a ridgeline. The airplane impacted a near-vertical mountain side in a nose-up, wings-level attitude. Witnesses reported hearing the airplane, but they were unable to see it due to the poor visibility near the accident site. Postaccident examination of the airplane revealed leading edge damage to both wings indicative of a controlled flight into terrain. An examination of the available wreckage did not reveal any anomalies that would have prevented normal operation of the flight controls. Although several engine components were not located at the accident site, witnesses reported hearing the engine operating up to the time of impact. Toxicology testing of the pilot’s blood detected the presence of gabapentin, which can produce impairing effect such as sleepiness, dizziness, and/or diminished coordination. However, if the pilot’s judgment was impaired, the copilot could have mitigated his improper decision making. Thus, it is unlikely that gabapentin’s effects on the pilot contributed to the accident. Based on the level attitude of the airplane when it impacted the rising terrain, it is likely the pilot had control of the airplane and flew into terrain that was obscured by the poor visibility.

Verbatim NTSB analysis and probable cause from the NTSB dataset