Incident Overview
The pilot of a twin-engine airplane reported hearing a loud noise and feeling his ears pop while cruising at about 12,900 feet. Radar data indicated that the airplane was on a straight and level flight path until about one hour before the incident, when it began a spiraling descent to the left. The flight path then became erratic, with altitude variations between 6,000 and 9,000 feet.
Pilot Report and Observations
The pilot stated that he had trouble seeing his instruments and felt confused. He believed he was landing at an airport in New Mexico near his ranch, but instead landed on a road in Arizona and struck light poles. Witnesses at the scene reported that the pilot appeared impaired and confused, but they did not detect any smell of alcohol. The pilot left the accident site and was not tested for alcohol or carbon monoxide poisoning. He reported that he did not consume any drugs or alcohol before or during the flight, but he did smoke three packs of cigarettes per day and also smoked cigars.
Examination of Systems
Examination of the pressurization and cabin air systems revealed a fractured clamp that could have prevented the cabin from maintaining pressurization. Additionally, there was evidence of engine exhaust by-products in some components of the pressurization system that should not have been exposed to engine exhaust. The specific source of the engine exhaust infusion into the pressurization system could not be determined.