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On May 7, 2010, about 0944 Pacific daylight time, a Cessna T206H, N663HP, collided with mountainous terrain while in cruise flight in the Anza Borrego Desert State Park, near Borrego Springs, California. The airplane was operated by the California Highway Patrol as a public-use surveillance aircraft. The commercial pilot was fatally injured and the airplane was substantially damaged and consumed by a post accident fire. Visual meteorological conditions prevailed, and a company flight plan had been filed. The flight originated from Thermal, California, about 0715.
Representatives of the California Highway Patrol (CHP) stated that between 0830 and 0920 the accident pilot was performing traffic surveillance activities with numerous CHP ground units in the vicinity of State Route (SR) 86 and Hoskins Street, 21 miles north of El Centro, California. The CHP officers decided to transfer their activities to Interstate-8 (I-8) and Dunaway Road, 14 miles west of El Centro. The CHP officers reported that by 1000 the airplane pilot had not checked in with them. At 1006, the dispatch operator for the California Department of Parks and Recreation received a call that someone saw smoke in the vicinity of Split Mountain (Anza Borrego). About 1600, wreckage of the CHP airplane was located on the east face of mountainous terrain, 2 miles north of Split Mountain.
Radar data for the accident airplane was provided by Salt Lake City Terminal Radar Approach Control (TRACON). The pilot was using a discrete transponder code of 1232, which allowed the radar track data to be identified and isolated. The radar data file begins at 0930, over Highway 78 about 4 miles south of the southern tip of the Salton Sea, at 1,600 feet mean sea level (msl). The terrain elevation at this location is approximately -150 feet msl. The radar track follows highway 78 north to where it intersects Highway 86, proceeds for 2.6 miles, and then abruptly turns southwest. While following Highway 78 the altitude recorded decreases from 1,600 feet msl to 1,100 feet msl, and then to 900 feet just before the track turns southwest. The track proceeds southwest at 1,200 feet, then turns west following Highway 78 for 5 miles while maintaining 1,200 feet. At 0940:43, the track turns southwest on a steady course of 225 degrees magnetic at 1,200 feet msl. This route was away from the highway and towards the rising mountainous terrain. The final radar return was at 0943:55, 1.7 miles northeast of the accident location. The accident location is located directly on the extended course line of 225 degrees from the last radar return, at the 1,070-foot elevation level. The highest terrain elevation in the vicinity of the accident site is 1,500 feet msl.
The pilot, age 39, held a commercial pilot certificate for airplane single engine land, with an instrument airplane rating issued on July 15, 2005. He held a second-class airman medical certificate with no limitations issued on April 19, 2010. The California Highway Patrol provided flight and training records for the pilot. The most recent flight summary was dated May 7, 2010, and listed the pilot's total flight time as 2,159.9 hours, with 30.9 hours in the previous 30 days. The pilot’s most recent annual flight review was conducted on November 20, 2009, in the same model of aircraft that was involved in the accident. His overall performance block was marked “satisfactory” on his flight check documentation. A review of the pilot’s recent activities indicated that his daily routine was unchanged; up at 0515, and home between 1530 and 1600. His eating habits were unchanged; light breakfast, afternoon meal, snack, and dinner around 1800. He would go to bed between 2230 and 2300. He had not complained about any physical ailments to his wife or colleagues. His wife stated that his sleep was sound and undisturbed.
The four seat, high-wing, fixed-gear, airplane, serial number (S/N) T20608212, was manufactured in 2000. It was powered by a Lycoming TIO-540-AJ1A, 310-hp engine and equipped with a 3 bladed McCauley constant speed propeller.
Review of the airplane's maintenance records revealed that a phase II airframe and engine inspection was completed on May 5, 2010, total aircraft time 10,096.8 hours, and 1,399.6 engine hours since major overhaul (SMOH). The airplane was equipped with an autopilot, and according to CHP personnel, all pilots are encouraged to use the autopilot when appropriate.
The El Centro automated surface observing system (ASOS) reported in part at 0956 the following weather: wind was from 350 degrees at 5 knots; with 10 statute miles visibility; the sky was clear of clouds; temperature 25 degrees Celsius (C); dew point 5 degrees C.
WRECKAGE AND IMPACT INFORMATION
The wreckage was located on the east face of a steep desert mountain in the Anza Borrego State Park, 2 miles north of Split Mountain. The 50-degree sloped terrain was the primary geographic characteristic of the accident scene. The direction of the debris path from the initial point of impact to the main wreckage was along the 220-degree bearing line. The majority of the wreckage was contained in a dry cut in the mountain side about the 1,070-foot msl level. It had been exposed to fire, which destroyed most of the cockpit, left wing, and fuselage. The right wing laid on top of the fuselage and had been sheared in half, in a chordwise direction, in an area between the flap and the aileron. The initial point of impact was identified by pieces of the right wing tip, engine exhaust stack, starter, alternator, nose strut, and one propeller blade, which were located on the north side of a small rock finger that made one side of the mountain cut. A black soot streak and partially burned vegetation originated on the north side of this rock finger, and expanded vertically in area around the main wreckage. A second propeller blade was located with the main wreckage, and the third propeller blade was located approximately 150 feet south and above the main wreckage. All three propeller blades exhibited leading edge gouges, and were deformed in a sinusoidal fashion along the length of each blade. The engine was situated horizontally on top of the cabin area.
On May 17, 2010, an additional wreckage examination was performed at the Aircraft Recovery Services facility in Pearblossom, California. The elevator trim actuator was not located. The flap actuator was observed fully retracted, which corresponds to zero degrees of flaps. Flight control continuity was established through multiple control cable overload separations and identification of the cable end ball fittings or control bell crank connections. Examination of the fire damaged engine and airframe did not reveal evidence of any abnormality or anomaly that would have precluded the normal operation of the engine or flight controls.
MEDICAL AND PATHOLOGICAL INFORMATION
The pilot’s most recent application for second-class Airman Medical Certificate was dated April 15, 2010. Review of the pilots medical records by the NTSB Medical Officer revealed the pilot had a history of back surgery for which he’d undergone treatment. He had received clearance to return to work without restrictions. The pilot had no reported history of coronary artery disease.
The autopsy was performed by the San Diego County Medical Examiner. The report noted the following observations in part, that the “coronary arteries are all contracted with very small lumens and what appears to be marked thickening of the walls, some of which is yellow consistent with atherosclerosis. The entire right coronary artery can be identified and has a very significantly narrowed lumen. … In the mid, lateral left ventricle is a full-thickness, vaguely wedge-shaped, 2 x 2 x 1.5 cm area where the myocardium of the left lateral ventricular wall is interrupted and replaced by considerably softer, pale, tan tissue, resembling fat. … The endocardium in this area appears fibrotic. … Microscopic Examination … RIGHT CORONARY ARTERY: Five cross sections show moderate to severe narrowing as a result of concentric mostly atheromatous atherosclerosis with cholesterol crystal clefts. There is up to 90% stenosis. Neither thrombus or [sic] hemorrhage are identified. There are considerable thermal changes. … Two sections of the abnormal area in the lateral left ventricular wall show endocardial fibrosis. In one of the sections there is severe attenuation of the wall and what appears to be transmural fibrosis and relatively small amounts of entrapped myocytes. In the other section the apparently fibrosis replaces at least the endocardial half of the thickness of the wall. No hemorrhage or inflammation is appreciated but the degree of thermal change makes it difficult to evaluate for the presence or absence of more acute ischemic changes. The epicardial artery included in the section shows moderate to severe atherosclerosis …” In the medical examiner’s opinion section of the report it states “..it is possible that a cardiac event due to fibrosis and/or ischemia due to his longstanding coronary arthrosclerosis could have precipitated the crash.”