Incident Overview
A certified flight instructor (CFI) and a student pilot were conducting a training flight when they decided to land on the grass next to the runway. According to the CFI, the student pilot had no prior experience landing on sod. The approach was described as normal but slightly low, a condition the CFI did not alert the student about, believing they could use power to clear the tall grass and descend into the grass strip.
Sequence of Events
Abeam the intended touchdown point, the CFI turned on the carburetor heat. On short final, the carburetor heat was turned off. At an altitude of approximately five feet, the student pilot attempted to add power to maintain altitude, but the engine did not respond. The student did not re-engage the carburetor heat. As a result, the airplane touched down short of the intended landing point, and the CFI was unable to reach the controls before the aircraft nosed over.
Post-Incident Findings
The aircraft sustained substantial damage to the fuselage and tail assembly. The CFI noted that no mechanical malfunctions or failures were known prior to the accident. He further stated that he had previously experienced the aircraft failing to respond to throttle inputs during landing and acknowledged that he should have kept the carburetor heat on during short final. When the temperature and dew point were plotted on a carburetor icing probability chart, the conditions fell within an area indicating moderate icing at cruise power or serious icing at glide power.
CFI's Remarks
The CFI reported that the approach was low but he assumed they could power over the grass. He did not inform the student of the low altitude. After the engine did not respond to throttle, the student did not turn the carburetor heat back on. The CFI expressed regret over his decision to turn off the carburetor heat, citing previous similar experiences.