On September 18, 1998, a Cessna 180 (registration N9407C) was involved in an aviation accident near Chalkitsik, AK. Investigators recorded the probable cause as: The pilot's failure to maintain directional control during takeoff due to landing gear sinking into soft mud. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A private pilot operating a tailwheel-equipped aircraft experienced a takeoff failure when the main landing gear sank into soft mud, causing the airplane to nose over and sustain substantial damage.
What happened
The accident occurred during the departure phase of flight from a remote airstrip. The pilot was operating a tailwheel-equipped airplane that had already completed three round trips earlier in the day, ferrying passengers and supplies between locations.
During the takeoff run for the fourth flight, approximately one-quarter of the way down the runway, the aircraft's main wheels encountered soft mud with a depth of about 10 inches. The ground conditions caused the landing gear to sink, resulting in a loss of directional control and forward momentum. The airplane subsequently nosed over onto its nose.
The investigation
Post-acc examination revealed substantial damage to the airframe. Specific components affected included the wings and the rudder. The failure mode was directly linked to the interaction between the tailwheel configuration, the soft ground surface, and the takeoff roll dynamics.
Probable cause
The pilot's failure to maintain directional control during takeoff due to landing gear sinking into soft mud.