Primary finding
Probable cause
The pilot's failure to extend the landing gear prior to touchdown.
Investigator assessment
Analysis narrative
The twin-engine airplane was being operated by the National Oceanic and Atmospheric Administration conducting snow survey flights. The airplane initially departed from the Grand Forks International Airport (GFK), Grand Forks, North Dakota, and made a refueling stop at the Fargo International Airport, Fargo, North Dakota. The airplane was on a repositioning flight back to GFK when the accident occurred. During the flight, the airplane was cleared by air traffic control for the runway 17R localizer backcourse approach to GFK. The airplane landed on runway 17R with the landing gear in the retracted position, resulting in substantial damage to the airplane. Subsequently, the engines were shut down and the aircraft was evacuated. The minimum descent altitude and visibility requirements for the approach were 1,200 feet above mean sea level (msl) and 1 mile respectively. The ceiling and visibility at the time of the accident were 800 feet (about 1,650 feet msl) and 1 mile respectively. The operator noted that there were no mechanical malfunctions.
Source record
Factual narrative
The twin-engine Rockwell AS-500S (Aero Commander) airplane was being operated by the National Oceanic and Atmospheric Administration conducting snow survey flights. The airplane initially departed from the Grand Forks International Airport (GFK), Grand Forks, North Dakota and made a refueling stop at the Fargo International Airport, Fargo, North Dakota. The airplane was on a repositioning flight back to GFK when the accident occurred. During the flight, the airplane was cleared by air traffic control for the runway 17R localizer backcourse approach to GFK. The airplane landed on runway 17R with the landing gear in the retracted position, resulting in substantial damage to the airplane. Subsequently, the engines were shut down and the aircraft was evacuated. The minimum descent altitude and visibility requirements for the approach were 1,200 feet above mean sea level (msl) and 1 mile respectively. The ceiling and visibility at the time of the accident were 800 feet (about 1,650 feet msl) and 1 mile respectively. The operator noted that there were no mechanical malfunctions.