What happened
While cruising at approximately 12,900 feet, the pilot of a twin-engine airplane reported hearing a loud noise and feeling his ears pop. Radar data indicated that the aircraft had maintained a relatively straight and level flight path until about one hour before the accident, at which point it began a spiraling descent to the left. Following this maneuver, the aircraft followed an erratic flight path with altitudes fluctuating between 6,000 and 9,000 feet.
The pilot reported experiencing confusion and difficulty reading his instruments. Believing he was approaching an airport in New Mexico near his ranch, the pilot instead landed on a road in Arizona, where the aircraft struck light poles. Witnesses at the scene noted that the pilot appeared confused and impaired, though they did not detect the smell of alcohol. The pilot left the site before any testing for alcohol or carbon monoxide poisoning could be conducted. He stated he had not consumed drugs or alcohol, but noted a heavy tobacco use.
The investigation
Investigators examined the aircraft's pressurization and cabin air systems. They discovered a fractured clamp that may have compromised the aircraft's ability to maintain cabin pressure. Furthermore, evidence of engine exhaust by-products was found within several components of the pressurization system that should not have been exposed to such contaminants. The specific source of how the engine exhaust entered the pressurization system remained undetermined.