On March 30, 1994, a Cessna 210D (registration N3820Y) operated by Gregersen, Marvin, D. was involved in an aviation accident near Cobalt, ID. Investigators recorded the probable cause as: THE PILOT SELECTED UNSUITABLE TERRAIN FOR LANDING. FACTORS IN THE ACCIDENT WERE: THE WET RUNWAY AND RISING TERRAIN THAT PRECLUDED A GO-AROUND. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot was unable to stop on a 2300-foot turf strip after landing, overrunning into a creek. He reported frost-covered grass made brakes ineffective; temperature was 35°F. Rising terrain prevented a go-around.
Accident Sequence
After landing on a 2300-foot-long turf airstrip, the pilot was unable to bring the airplane to a stop before it overran the upwind end and entered a creek.
Pilot Report
The pilot stated that the grass surface was covered with a half-melted coat of frost, which rendered the brakes ineffective. He also noted that the temperature was 35 degrees Fahrenheit. According to the pilot, rising terrain at the upwind end of the strip precluded the option of a go-around. Additionally, the pilot reported that he had not flown into the airstrip for several years.
Environmental Conditions
The airstrip was a turf surface. The presence of partially melted frost on the grass was identified by the pilot as the reason for the lack of braking effectiveness. The ambient temperature at the time was 35°F.