Event Summary
During an en route flight to the company's home airport, the twin-engine airplane either experienced a loss of power to the right engine, or the pilot decided to shut that engine down. The home airport reported night visual meteorological conditions, and no malfunction was found with the remaining engine. Despite this, the pilot opted to fly a night precision instrument approach to an airport 45 nautical miles closer, which had a visibility of 1 mile and a ceiling of 100 feet. Unknown to the pilot, fog was also present at that airport. The pilot did not advise or seek assistance from air traffic control or the company.
Approach and Missed Attempt
When the airplane broke out of the clouds, it was not stable. Approaching the runway with full flaps and exceeding the 25 percent maximum for a go-around, the pilot added full power to the left engine. The high power setting, slow airspeed, and full flaps configuration resulted in a minimum control speed (Vmc) roll.
Investigation Findings
Investigators could not determine why the right engine was inoperative. No mechanical or fuel-related anomalies were found that would have precluded normal operation. The official probable cause was the pilot's improper decision to attempt a single-engine missed approach with the airplane in a slow airspeed, full flap configuration, which resulted in a Vmc roll. Contributing factors included an inoperative engine for undetermined reasons, the pilot's in-flight decision to divert to an airport with low ceilings and visibility while better conditions existed elsewhere, the pilot's failure to advise or seek assistance from air traffic control or the company, and the low cloud ceilings, fog, and night lighting conditions.