Taylorcraft BC12-D N94973 accident near Clutier, Iowa

Probable cause

The pilot’s failure to monitor, recognize, and identify obstacles on approach to landing, which resulted in an inadvertent collision with power lines. Contributing to the accident was the pilot’s expectation and assumption that there were no above-ground power lines in the area.

NTSB analysis

The airplane was on approach to an unimproved airstrip when it struck power lines and then impacted terrain. The pilot had previously flown into this airstrip but had not done so recently. When the field was previously used as an airstrip, the power lines were buried; however, the power lines had recently been moved above ground. The pilot may not have been aware that the power lines had been moved above ground, and the lines were not marked. The surviving passenger stated that he never saw the power lines before the airplane struck them.

The pilot's medical records revealed diagnoses of hypertension, diabetes, high cholesterol, and bipolar disease. Toxicology testing showed the presence of medications consistent with the treatment of these conditions. Although the pilot’s medical records and toxicology results indicated that the pilot had recently stopped taking some medications that could have adversely affected his performance, his bipolar disease would have had significant negative effects on cognition, including memory and executive functioning/judgment, and would have been disqualifying for a medical certification. Therefore, although it is possible that the pilot's underlying psychiatric disease and its treatment may have affected his judgment, it is not possible to determine the extent to which it may have contributed to the accident.

Text from the NTSB. Open the NTSB docket for CEN13FA078 for the full record.