On April 7, 1994, at 2335 Pacific daylight time, a Cessna 182N, N9124G, collided with a vineyard near Kerman, California, following an uncontrolled altitude deviation from cruise. The aircraft was owned and operated by the pilot. Visual meteorological conditions prevailed at the time and an IFR flight plan was filed. The aircraft incurred substantial damage and the certificated private pilot, the sole occupant, sustained serious injuries. The flight originated at Long Beach, California, on the day of the accident at 2113 hours as a cross-country personal flight to Modesto, California.

During the investigation, Federal Aviation Administration (FAA) air-to-ground communications tapes, recorded radar data, and statements from controllers from all air traffic control facilities which worked the flight were reviewed. A radar flightpath chart of the last 30 minutes of flight, and transcripts of the radio communications are attached to this report.

The review revealed that within 15 minutes of takeoff, while being radar vectored by Southern California terminal radar approach control (SOCAL TRACON), the aircraft began deviating slightly from assigned headings, altitudes, and the ground controller's instructions. As an example, while being radar vectored over the Los Angeles International Airport, the pilot performed several 360-degree turns. In response to the controller's inquiry, the pilot responded that he wanted to look at the city lights one last time before he left. The facilities which worked the flight in successive order reported that the aircraft was erratic in the course flown over an extended period of time, with the erratic behavior becoming progressively worse as the flight continued. The pilot seemed to have difficulty maintaining his orientation, drifted significantly off his assigned airways and headings, and had done several 360- and 180-degree turns. In the latter stages of the flight, the controllers reported that the pilot became more unresponsive to their attempts at radio contact and air traffic control (ATC) instructions.

The pilot was interviewed several times by both FAA and National Transportation Safety Board investigators. The pilot reported that in the initial part of his climb after takeoff he turned on the cabin heat because he felt cold. He stated that he recalled doing the 360-degree turns over Los Angeles International Airport because he wanted to take a last look at the lights of the Los Angeles basin and he remembered the controller being very irritated. The pilot said he did not recall very clearly the turns in the wrong direction. He did recall eventually being handed off to Los Angeles air route traffice control center (ARTCC) and reaching his assigned cruise altitude of 11,000 feet mean sea level (msl).

Shortly after reaching cruise altitude, the pilot began to experience blurred vision, headaches, and nausea. He stated that his breathing became very labored and he felt the aircraft altitude was very difficult to control due to turbulence. He recalled being handed off to Oakland ARTCC and asking for a visual flight rules (VFR) on top clearance direct to Modesto at 6,500 feet. He stated that the controller was very difficult to understand, but he eventually descended in accordance with the VFR on top direct clearance.

After descending to what he believed was 6,500 feet, the flight controls became more difficult to move and the flight path of the airplane kept changing direction and altitude. He said that no matter how hard he tried to stay awake he would drift off, then find himself in what he thought at the time were turns. He remembered thinking that he had to get control of the aircraft, but he could not make his arms and hands move. He said he does not remember anything after that until waking up in the hospital emergency room.


The aircraft wreckage was examined in detail both on site and after recovery by FAA airworthiness inspectors from the Fresno, California, Flight Standards District Office. The engine compartment, fuselage, and cabin were specifically examined for evidence of exhaust gas intrusion into the occupiable areas of the aircraft. The inspector's report is attached.

The exhaust manifold and tubes were examined. The connecting clamp for the Nos. 1 and 3 exhaust tubes exhibited gas blow-by stains. A pin hole with exhaust stains was observed on the cylinder No. 6 tube at a point about 5 inches from the flange. Gas blow-by stains were also evident on the cylinder No. 6 tube at the lower manifold clamp.

The heat exchanger inner liner was found to be burned out. The muff clamps exhibited evidence of leakage.

The heat box and mixer duct had exhaust stains on the valve face and around the hot air exit. Small holes were noted in the heater air duct material.

The nose wheel steering boots had holes worn in the material. Exhaust stains were observed on the aircraft belly skin, principally on the right side of the fuselage. Inspection panels in the area did not appear to seal adequately and exhibited exhaust-type stains in and around the internal sides. The strobe light assembly was improperly sealed, with evidence of exhaust stains noted internally.


The pilot sustained serious injuries in the accident and was transported by ambulance to Valley Medical Center in Fresno, California, for admission and treatment of his injuries. While a blood test for alcohol was not performed, the admitting emergency room physician reported that he did not detect the odor of alcohol and the patient did not exhibit symptoms which would cause him to suspect alcohol. The hospital blood screen for drug substances was negative.

At the request of the National Transportation Safety Board, a blood test for carbon monoxide was performed approximately 11 hours after admission to the hospital. The blood saturation was found to be 3 percent; however, hospital records noted that the pilot had been under continuous oxygen therapy since admission.

An FAA flight surgeon in AAM-611 at the Civil Aeromedical Institute (CAMI) was contacted by telephone. The doctor verbally reported that carbon monoxide (CO) poisoning has a fairly rapid onset and has the following typical symptoms for the stated CO levels: at 20 percent, nausea and blurred vision; at 30 percent, headache and some impairment of motor functions; at 40 percent, near unconsciousness to death. The flight surgeon also stated that CO has a half-life of 45 minutes under oxygen therapy (1/2 of the CO blood saturation is eliminated) and that 5 half-lives typically yields a 98 percent reduction in the CO level.

The flight surgeon reviewed the audio tapes of the recorded air- to-ground communications between the pilot and the involved air traffic facilities. The doctor reported that CO poisoning is a plausible and likely occurrence in this instance.

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