Accident Overview
On the day of the accident, an aircraft operating as Alaska Central Express Flight 51 was destroyed when it impacted rising terrain approximately 10 miles east of Aleknagik, Alaska. The airplane was conducting an on-demand cargo flight under 14 Code of Federal Regulations Part 135, with an airline transport certificated captain and a commercial certificated first officer aboard. Both pilots sustained fatal injuries.
Flight History
The flight departed Anchorage, Alaska, at about 0544 and made a scheduled stop at King Salmon before continuing to Dillingham, Alaska. While approaching Dillingham, the flight crew requested the RNAV GPS 19 instrument approach to Dillingham Airport from controllers at the Anchorage Air Route Traffic Control Center (ARTCC) around 0757. The ARTCC specialist granted the clearance with instructions to proceed direct to the Initial Approach Fix (IAF) and maintain an altitude of 2,000 feet or above.
Shortly thereafter, the crew requested to enter a holding pattern at the IAF to contact the Flight Service Station for a runway conditions report, which the controller approved. The ARTCC specialist subsequently made several attempts to contact the aircraft but was unsuccessful and lost radar track. When the airplane failed to arrive at Dillingham, ARTCC personnel initiated a radio search and, unable to locate the aircraft, issued an alert notice at 0835.
Search and Recovery
Search personnel from the Alaska State Troopers, Alaska Air National Guard, U.S. Coast Guard, and volunteer pilots conducted an extensive search. An Air National Guard C-130 tracked a 406 MHz emergency locator transmitter signal to an area of mountainous terrain about 20 miles north of Dillingham. Poor weather prevented searchers from reaching the site until the following morning. Upon arrival, a crew from the Air National Guard's 210th Air Rescue Squadron in an HH-60G helicopter confirmed that both pilots had sustained fatal injuries at the steep, snow- and ice-covered site.
Probable Cause
The NTSB determined the probable cause of the accident was the flight crew's failure to maintain terrain clearance, resulting in controlled flight into terrain in instrument meteorological conditions. Contributing factors included the flight crew's failure to correctly read back and interpret clearance altitudes issued by the air traffic controller, their failure to adhere to minimum altitudes on the published instrument approach chart, and their failure to adhere to company checklists. Also contributing was the controller's issuance of an ambiguous clearance, which led to the airplane's premature descent, his failure to address the pilot's incorrect read back of assigned altitudes, and his failure to monitor the flight and issue terrain-based safety alerts.