Casualties unknown

Airplane Impacts Terrain After Encountering Ice on Stabilizer (N5087Q)

Watertown, SD, US

On December 31, 1997, a Cessna 402B (registration N5087Q) operated by Sioux Falls Aviation was involved in an aviation accident near Watertown, SD. Investigators recorded the probable cause as: the pilot's failure to perform an aircraft preflight and to remove the ice which had accumulated on the airframe. A factor involved in the accident was the icing weather conditions which existed and the ice which accumulated on the airplane. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 1 related events involving the same aircraft type or operator are linked below.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-10Data APIEditorial standards

An airplane landed at Watertown, loaded and off-loaded cargo, then departed. Witnesses reported bouncing and buffeting at low altitude. The airplane descended, impacted terrain, and exploded. Post-accident inspection revealed rime ice on the left horizontal stabilizer.

Incident Overview

A pilot landed an airplane at Watertown to load and off-load cargo. Without exiting the aircraft, the pilot departed the location. A witness observed the airplane passing over the runway at an altitude of approximately 50 feet above ground level, describing the aircraft as bouncing and buffeting during the flight. Another witness reported that the weather at the time was overcast with occasional snow flakes.

Accident Sequence

Shortly after being observed over the runway, the airplane descended and impacted the terrain. The impact resulted in an explosion.

Post-Accident Findings

A post-accident inspection of the wreckage revealed a ridge of rime ice measuring between 1/2 and 3/4 inch thick along the leading edge of the left horizontal stabilizer. Additionally, pieces of arc-shaped ice were found scattered along the wreckage path. Examination of the wreckage did not identify any preimpact failure or malfunction of the engine or airframe that would have prevented flight.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001208X09286. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.