On September 16, 2001, about 0745 mountain standard time, a Cessna 172L single engine airplane, N4312Q, was destroyed during the collision with, and subsequent fire, a residence at Tucson, Arizona. The pilot, who was the sole occupant, received fatal injuries; no one on the ground was injured. The airplane was registered to, and operated by, the pilot under the provisions of 14 CFR Part 91 as a personal flight. Visual meteorological conditions prevailed, and a flight plan had not been filed. The flight originated at La Cholla Airpark, a private uncontrolled residential airport, about 0715. The accident occurred 5 days after the September 11, 2001, terrorist attacks, and during the period when the Federal Aviation Administration (FAA) prohibited general aviation visual flight rule (VFR) flights under the provisions of 14 CFR Part 91.139; Emergency Air Traffic Rules. After departure, the airplane was identified by the Tucson Terminal Radar Approach Control (TRACON). TRACON transmitted on a sector frequency in the blind advising the airplane to return to the point of departure; at that time the airplane's transponder was squawking 1233. There was no response from the airplane, but it subsequently reversed course and the transponder code was changed to 1203. The last altitude observed by TRACON was 3,500 feet msl. According to the Pima County Sheriff's Department report, a sergeant from the sheriff's department observed the airplane flying from the south to the north, and "seemed to be turning directly into the ground. He observed the airplane in a "deep dive," with the nose of the airplane headed "down towards the ground." The sergeant lost sight of the airplane when it disappeared behind a tree line. The sergeant then noted smoke emanating form the area where the airplane was last seen. The sergeant activated his emergency equipment and responded to the accident site. He found the airplane sticking out of the side of a garage of a residence. Fire consumed the garage and airplane. The sheriff's department personnel contacted personnel at the La Cholla Airpark and were told the pilot was having some personal problems. The pilot's wife told sheriff department personnel that the airplane had not flown in 5 years and her husband had never flown the airplane before. The private pilot held a third-class medical certificate that was issued on April 26, 2000, with a limitation to have glasses available for near vision. An autopsy was conducted on the pilot by a forensic pathologist for the Pima County Sheriff's Department, and it was determined the pilot died as a result of the injuries sustained during the impact with the house. According to the forensic pathologist that conducted the autopsy, while the pilot "had threatened suicide in the past," no evidence existed to form the conclusion that pilot intended suicide during the accident flight. The Pima County Sheriff's Department listed the cause of death as accidental due to an airplane crash. Toxicology tests conducted on the pilot revealed he tested positive for the following: 63 mg/dL ethanol detected in kidney 128 mg/dL ethanol detected in muscle 8 mg/dL acetaldehyde detected in kidney 13 mg/dL acetaldehyde detected in muscle 1 mg/dL n-butanol detected in muscle 1 mg/dL n-propanol detected in muscle The following were not given a quantity. Fluoxetine in liver Norfluoxetine in liver Norfluoxetine in muscle Nordiazepam in liver Nordiazepam in kidney Oxazepam in kidney Verapamil in liver Verapamil in muscle Norverapamil in liver Norverapamil in muscle According to the toxicological report, the ethanol found "may potentially be from postmortem ethanol formation and not from ingestion of ethanol." Fluoxetine is an antidepressant medication, and Nordiazepam is an antidepressant/antianxiety drug. Verapamil is a high blood pressure medication.