NYC00FA039 · Beech S35

The pilot departed on an instrument flight plan in instrument conditions, contacted departure control, and then reported a gyro problem. The airplane continued to fly for approximately 2 minutes. During this period, heading, altitude, and airspeed continued to change; and the pilot did not comply with any ATC instructions. The airplane crashed into a residential area. The pilot had approximately 5,800 hours of total flight experience, with 120 hours of that in the last 6 months. In addition, he had 1,308 hours of actual instrument experience. Static marks consistent with no or little rotation were observed on the horizontal-situation-indicator-gyro rotor. Toxicological test performed on the pilot revealed 3.239 (ug/ml, ug/g) of butalbital (a barbiturate) in muscle. On a non FAA 'Adult Physical Examination' form physician's notes indicate 'Past Medical History: Migraine headaches-uses Fiorinal [butalbital (a barbiturate), aspirin, and caffeine] up to 2 times per week...'. The 1999 physician's desk reference lists the most frequent adverse reactions to Fiorinal as drowsiness and dizziness. From 1992 to October 1999, the pilot was prescribed over 6,000 tablets of Fiorinal or the generic equivalent, with 800 of that being in the last year. On all the pilot's FAA medical applications, he stated he was not taking any prescription or nonprescription medication, and had never suffered from severe or frequent headaches.

Verbatim NTSB analysis and probable cause from the NTSB dataset