Incident Sequence
On 22 November 1996, at 1720 Pacific Standard Time, King 56 departed Portland International Airport on an instrument flight rules (IFR) flight bound for North Island Naval Air Station. The mission was an overwater navigation evaluation. After a normal takeoff and climb, the aircraft reached flight level 220. One hour and 24 minutes after takeoff, while in level flight, the flight engineer commented on a torque fluctuation on the number 1 engine. No anomalies were noted on the cockpit voice recorder (CVR), digital flight data recorder (DFDR), or in survivor testimony prior to this remark.
Over the next three minutes, all four engines became unstable and eventually failed. The crew attempted to manage the emergency by placing the propellers in mechanical governing, a procedure consistent with a four-engine rollback. The DFDR and CVR do not confirm whether mechanical governing was successfully selected on all propellers.
Emergency Response
The crew declared an in-flight emergency with Oakland Air Route Traffic Control Center (ARTCC) and turned the aircraft east toward Kingsley Field in Klamath Falls, Oregon, approximately 230 miles away and 80 miles from the coast. The radio operator notified the United States Coast Guard Humboldt Bay Station.
During the turn, the number 3 and number 4 engines briefly recovered most of their torque, as recorded by the DFDR. However, when the number 3 engine's RPM dropped below 94%, the last generator producing electrical power went offline due to low frequency, resulting in total electrical power loss at 1846 PST. Power was later restored to battery-powered equipment, but the aircraft then glided toward a ditching.
Ditching and Wreckage
The aircraft attempted a ditching into the Pacific Ocean. Post-impact, the outboard wing sections and all four engines separated from the center wing section, which then detached from the fuselage. The engines and fuselage sank directly to the ocean floor at a depth of approximately 5,500 feet. The outer and center wing sections floated for several days before sinking more than 50 nautical miles from the impact location.
The radio navigator was rescued by the Coast Guard. Ten other crew members were killed.
Investigation and Probable Cause
The investigation determined that the mishap was caused by fuel starvation for reasons that could not be identified.