Accident Overview
During an approach to the airport, the airplane entered a left turn that a surviving passenger described as "almost completely upside down." The airplane briefly leveled, then executed another left turn with an equally severe bank angle. After rolling level, it entered a steep dive and collided with a building.
Passenger Observations
The passenger reported that the engines were running normally throughout the flight. The steep turns performed by the pilot did not concern her, as she had flown with him previously and knew he "liked to make sharp turns."
Aircraft Examination
Examination of the airplane and engines revealed no pre-impact mechanical anomalies.
Weather Conditions
Weather at the time included a broken cloud ceiling of 1,100 feet and 3 miles visibility in mist.
Aerodynamic Reference
According to the FAA's "Airplane Flying Handbook," an airplane will stall at a higher indicated airspeed when excessive maneuvering loads are imposed by steep turns, pull-ups, or other abrupt flight path changes. A review of the Pilot's Operating Handbook (POH) "Stall Speeds - Power Idle" chart showed that with approach flaps selected and a bank angle of 60 degrees, the airplane would stall at about 123 knots.
Radar Data
Radar data indicated the airplane descended along the approach course at an average speed of 120 knots.
Toxicology and Medical History
Toxicology testing on the pilot revealed imipramine and carbamazepine in his urine and blood, and morphine in his urine. Medical and pharmacy records showed he suffered from a severe neurological disorder, possibly a seizure disorder, causing frequent, unpredictable episodes of debilitating pain. Approximately three months prior, he was diagnosed with viral meningitis and a severe skin infection with multiple abscesses. The pilot had been prescribed imipramine (an antidepressant that can impair driving and cognitive functions) and carbamazepine (used for seizures or chronic pain, which can impair psychomotor performance). Morphine, a prescription opiate painkiller (also a metabolite of heroin and some medications like codeine), was found, but no recent prescription for opiates was noted in his records. Neither his medical condition nor the medications he routinely took were reported on his application for an airman medical certificate.
Probable Cause
The probable cause, as stated in the official findings, is: The pilot's low altitude maneuver using an excessive bank angle, and his failure to maintain airspeed which resulted in an inadvertent stall and subsequent collision with a building. A factor was the pilot's impairment from prescription medications.