NTSB Identification: LAX94LA184.
The docket is stored in the (offline) NTSBImaging System.
Accident occurred APR-07-94 at KERMAN, CA
Aircraft: CESSNA 182N, registration: N9124G
Injuries: 1 Serious.
RECORDED RADAR & VOICE TAPES REVEALED THAT 15 MINUTES AFTER TAKEOFF, THE AIRCRAFTBEGAN DEVIATING FROM HEADINGS, ALTITUDES, & ATC INSTRUCTIONS. THE FACILITIES WORKINGTHE FLIGHT SAID THE AIRCRAFT’S COURSE OF FLIGHT WAS ERRATIC, WITH THE ERRATIC BEHAVIORBECOMING WORSE AS THE FLIGHT CONTINUED. THE PILOT SEEMED TO BE DISORIENTED. THE AIRCRAFTDRIFTED SIGNIFICANTLY OFF ASSIGNED AIRWAYS & HEADINGS, & DID SEVERAL 360 & 180DEGREE TURNS. THE PILOT SAID THAT AFTER REACHING CRUISE ALTITUDE, HE BEGAN TO EXPERIENCEBLURRED VISION, HEADACHES, & NAUSEA. HE SAID HIS BREATHING BECAME LABORED, & THECONTROLS BECAME DIFFICULT TO MOVE. THE FLIGHTPATH OF THE AIRPLANE KEPT CHANGING DIRECTION& ALTITUDE, & THE PILOT COULD NOT STAY AWAKE. MANY SMALL LEAKS WERE FOUND IN THEEXHAUST SYSTEM, WITH GAS PATHWAYS FOUND INTO THE CABIN. HOSPITAL TESTS FOR ALCOHOL &DRUGS WERE NEGATIVE. AN FAA FLIGHT SURGEON AT CAMI REVIEWED THE CASE & REPORTED THATTHE SYMPTOMS WERE CONSISTENT WITH CARBON MONOXIDE POISONING. BLOOD DRAWN 11 HRS AFTERENTERING A HOSPITAL RETAINED 3% SATURATION WITH CARBON MONOXIDE.
Probable Cause
AN EXHAUST GAS LEAK, DUE TO INADEQUATE MAINTENANCE, WHICH RESULTED IN CARBON MONOXIDEPOISONING, INCAPACITION OF THE PILOT, AND LOSS OF AIRCRAFT CONTROL.
On April 7, 1994, at 2335 Pacific daylight time, a Cessna 182N, N9124G, collided with avineyard near Kerman, California, following an uncontrolled altitude deviation fromcruise. The aircraft was owned and operated by the pilot. Visual meteorological conditionsprevailed at the time and an IFR flight plan was filed. The aircraft incurred substantialdamage 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 hoursas a cross-country personal flight to Modesto, California.
During the investigation, Federal Aviation Administration (FAA) air-to-groundcommunications tapes, recorded radar data, and statements from controllers from all airtraffic control facilities which worked the flight were reviewed. A radar flightpath chartof the last 30 minutes of flight, and transcripts of the radio communications are attachedto this report.
The review revealed that within 15 minutes of takeoff, while being radar vectored bySouthern California terminal radar approach control (SOCAL TRACON), the aircraft begandeviating slightly from assigned headings, altitudes, and the ground controller’sinstructions. As an example, while being radar vectored over the Los Angeles InternationalAirport, the pilot performed several 360-degree turns. In response to the controller’sinquiry, the pilot responded that he wanted to look at the city lights one last timebefore he left. The facilities which worked the flight in successive order reported thatthe aircraft was erratic in the course flown over an extended period of time, with theerratic behavior becoming progressively worse as the flight continued. The pilot seemed tohave difficulty maintaining his orientation, drifted significantly off his assignedairways and headings, and had done several 360- and 180-degree turns. In the latter stagesof the flight, the controllers reported that the pilot became more unresponsive to theirattempts at radio contact and air traffic control (ATC) instructions.
The pilot was interviewed several times by both FAA and National Transportation SafetyBoard investigators. The pilot reported that in the initial part of his climb aftertakeoff he turned on the cabin heat because he felt cold. He stated that he recalled doingthe 360-degree turns over Los Angeles International Airport because he wanted to take alast look at the lights of the Los Angeles basin and he remembered the controller beingvery irritated. The pilot said he did not recall very clearly the turns in the wrongdirection. He did recall eventually being handed off to Los Angeles air route trafficecontrol center (ARTCC) and reaching his assigned cruise altitude of 11,000 feet mean sealevel (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 theaircraft altitude was very difficult to control due to turbulence. He recalled beinghanded off to Oakland ARTCC and asking for a visual flight rules (VFR) on top clearancedirect to Modesto at 6,500 feet. He stated that the controller was very difficult tounderstand, but he eventually descended in accordance with the VFR on top directclearance.
After descending to what he believed was 6,500 feet, the flight controls became moredifficult to move and the flight path of the airplane kept changing direction andaltitude. He said that no matter how hard he tried to stay awake he would drift off, thenfind himself in what he thought at the time were turns. He remembered thinking that he hadto get control of the aircraft, but he could not make his arms and hands move. He said hedoes not remember anything after that until waking up in the hospital emergency room.
WRECKAGE EXAMINATION
The aircraft wreckage was examined in detail both on site and after recovery by FAAairworthiness inspectors from the Fresno, California, Flight Standards District Office.The engine compartment, fuselage, and cabin were specifically examined for evidence ofexhaust gas intrusion into the occupiable areas of the aircraft. The inspector’s report isattached.
The exhaust manifold and tubes were examined. The connecting clamp for the Nos. 1 and 3exhaust tubes exhibited gas blow-by stains. A pin hole with exhaust stains was observed onthe cylinder No. 6 tube at a point about 5 inches from the flange. Gas blow-by stains werealso 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 exhibitedevidence of leakage.
The heat box and mixer duct had exhaust stains on the valve face and around the hot airexit. Small holes were noted in the heater air duct material.
The nose wheel steering boots had holes worn in the material. Exhaust stains wereobserved 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-typestains in and around the internal sides. The strobe light assembly was improperly sealed,with evidence of exhaust stains noted internally.
MEDICAL AND TOXICOLOGICAL INFORMATION
The pilot sustained serious injuries in the accident and was transported by ambulanceto Valley Medical Center in Fresno, California, for admission and treatment of hisinjuries. While a blood test for alcohol was not performed, the admitting emergency roomphysician reported that he did not detect the odor of alcohol and the patient did notexhibit symptoms which would cause him to suspect alcohol. The hospital blood screen fordrug substances was negative.
At the request of the National Transportation Safety Board, a blood test for carbonmonoxide was performed approximately 11 hours after admission to the hospital. The bloodsaturation was found to be 3 percent; however, hospital records noted that the pilot hadbeen under continuous oxygen therapy since admission.
An FAA flight surgeon in AAM-611 at the Civil Aeromedical Institute (CAMI) wascontacted by telephone. The doctor verbally reported that carbon monoxide (CO) poisoninghas 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 ofmotor functions; at 40 percent, near unconsciousness to death. The flight surgeon alsostated that CO has a half-life of 45 minutes under oxygen therapy (1/2 of the CO bloodsaturation is eliminated) and that 5 half-lives typically yields a 98 percent reduction inthe CO level.
The flight surgeon reviewed the audio tapes of the recorded air- to-groundcommunications between the pilot and the involved air traffic facilities. The doctorreported that CO poisoning is a plausible and likely occurrence in this instance.
