History of Flight
On July 23, 2011, at 1023 Pacific daylight time, an American Aviation AA-1A, N34299, collided with mountainous terrain near Corona, California. The pilot was operating the airplane under 14 CFR Part 91. The certified flight instructor (CFI) and student pilot sustained fatal injuries. The airplane sustained substantial damage and was consumed by post-impact fire. The local instructional flight departed Chino Airport, Chino, California, at 1015. Visual meteorological conditions prevailed, and no flight plan was filed.
The CFI had recently joined Duke's Flying Club (DFC) as an instructor. According to the manager of DFC, the flight was an introductory lesson for the student pilot, with a destination of Lake Matthews, about 15 miles southeast of Chino. The CFI joined DFC in June 2011, and this was his second flight with the club as an instructor.
A witness, located in her bedroom about 600 feet northeast of the accident site, heard an aircraft fly overhead. She described the sound as much louder than usual and lower. She ran outside and observed the airplane flying west to left just above a ridgeline. The airplane made an abrupt, swooping, descending left turn. She described the turn as extravagant and similar to an aerobatic maneuver. As the airplane rolled out, the wings began to rock side to side, then immediately descended nose-down into the ground. She stated the airplane did not trail smoke or vapors, and the engine produced a sound consistent with high power. Weather at the time was calm winds and clear skies.
The FAA provided radar and air traffic control audio data. Radar revealed a target with a 1200 beacon code and no altitude information, departing Chino Airport airspace at 1018. The target traveled southeast over Corona Municipal Airport. At 1023, it began a left turn, then a right turn, and continued south. After 10 seconds, the target began a 50-degree left turn, followed 5 seconds later by a 90-degree right turn towards mountainous terrain. Wreckage was located about 200 feet east of the final radar return.
Audio data indicated that Chino Tower personnel located the airplane's primary radar target after departure, but it did not transmit altitude. The pilot reported cycling the transponder and switching to non-altitude reporting mode. Tower provided traffic advisories and approved a frequency change. The pilot reported climbing from 1,800 to 2,500 feet. The last recorded transmission occurred about 5 minutes after takeoff, when the pilot inadvertently transmitted his position to Corona Airport traffic on Chino frequency.
Personnel Information
The CFI was 18 years old. His flight records were not recovered and assumed destroyed. FAA records showed he first received a private pilot certificate with a glider rating in November 2008. He obtained a commercial pilot certificate with airplane single-engine land and instrument airplane ratings on January 24, 2011. He was issued a CFI certificate with airplane single-engine land rating on March 21, 2011. According to his applications, he had 301.2 hours flight experience at the time of commercial certificate application and 350 hours at the time of CFI application. Acquaintances reported that all his glider experience was in Civil Air Patrol aircraft, and his experience with the Grumman AA-1A series was limited to the prior instructional flight and an introductory flight with the manager. All his powered airplane check rides were conducted by the same FAA examiner. He held a first-class medical certificate issued July 15, 2010, with no limitations or waivers.
The student pilot was 19 years old. FAA records showed he did not hold a combined student pilot/medical certificate or any other rating. FAA regulations do not require such a certificate during dual flight training.
Aircraft Information
The low-wing, two-seat airplane, serial number AA1A-0270, was manufactured in 1971. It was powered by a four-cylinder Lycoming O-235-C2C engine, serial number L-10639-15, and equipped with a fixed pitch McCauley metal propeller. Airframe and engine maintenance logbooks showed the airplane had undergone an annual inspection completed the day prior to the accident. At that time, the airplane had accrued 6,545.02 flight hours, with the engine accumulating 1,652.32 hours since overhaul in 2003.
Meteorological Information
An automated surface weather observation at Corona Airport (elevation 533 feet msl, 5 miles northwest of the accident site) was issued 27 minutes prior to the accident. It indicated variable wind at 3 knots; 5 miles visibility in haze; clear skies; temperature 21°C; dew point 14°C; and an altimeter setting of 29.95 inches of mercury.
Wreckage and Impact Information
The wreckage was located in foothills adjacent to the northern region of the Cleveland National Forest, about 10 miles south-southeast of Chino Airport and 7 miles west of Lake Matthews. The accident site was on a 15-degree northeast-facing slope at the 1,500-foot level. Terrain consisted of waist-high scrub brush and trees 10-30 feet tall. From the wreckage location, terrain rose to the 4,007-foot peak of Mount Pleasant about 2.5 miles west. The mountain range continued 8 miles southeast to Santiago Peak at 5,720 feet.
The first identified point of impact was a ground disruption in soft dirt containing the propeller, a section of engine cowling, and fragments of engine flywheel, canopy frame, and Plexiglas. Both propeller blades remained attached to the hub with chordwise scoring. The composite propeller spinner was fragmented. One blade was curled aft about 90 degrees from the root; the second blade had about 15 degrees of tip twist. The engine and nose landing gear structure separated from the fuselage and were located about 20 feet downhill. The main wreckage was 15 feet downhill, consisting of the primary fuselage structure, tail section, and both wings, all thermally destroyed. Partial ash remnants of wings, control surfaces, and fuselage remained. Both wing spars came to rest on an east-west heading, partially attached to landing gear struts and cabin seats. Burnt remnants of cabin controls, tailcone, and empennage were underneath the wing spar center section. The rudder control cable was continuous from rudder horns to foot pedals. Fragmented sections of control yokes, foot pedals, and flight instruments remained within the vicinity. No impact damage or witness marks were noted on surrounding trees. The post-accident fire burned about 1 acre to the northwest.
Medical and Pathological Information
The County of Riverside Sheriff-Coroner conducted postmortem examinations of both pilots. Cause of death was reported as multiple blunt force traumatic injuries. Toxicological specimens were tested by the FAA Civil Aerospace Medical Institute (CAMI). Analysis showed no findings for carbon monoxide or cyanide for the CFI, with negative results for all screened drug substances and ingested alcohol. For the student pilot, analysis showed negative results for cyanide and ingested alcohol, with 2.711 ug/ml ug/g acetaminophen detected in blood. Specimens were unsuitable for carbon monoxide analysis. According to CAMI, acetaminophen has a therapeutic low of 5.0 and high of 50.0 ug/ml.
Tests and Research
The engine was examined after removal from the wreckage. It sustained extensive thermal damage; all ancillary hoses, cables, and lines were destroyed. The aft sections of both magnetos and carburetor bowl had melted. The forward engine case was bent, impinging the crankshaft at the forward bearing. The propeller crankshaft flange remained attached with a torn section. Top spark plugs exhibited black sooting consistent with thermal damage. Plugs one, two, and three showed wear signatures consistent with normal operation; plug three showed worn out normal signatures. Cylinder heads were examined via borescope; piston crowns and valves had grey deposits with black sooting. No valve-to-piston contact or other mechanical damage was observed. Damage to the forward crankshaft and engine casing precluded rotation of the engine's drive train. Rocker covers revealed all springs and rockers to be oil wet. No evidence of preimpact mechanical malfunction was noted.
Radar data indicated the airplane's groundspeed as it approached the final turn was about 96 knots, reducing to 77 knots during the turn, with a radius of about 400 feet. Referring to Aerodynamics for Naval Aviators, the airplane's angle of bank was between 50 and 60 degrees. According to the Flight Manual, stall speed at a bank angle of 60 degrees, maximum gross weight, and forward center of gravity loading was 79 knots calibrated airspeed with flaps up, and 75 knots with flaps down. Flap position at the time of the accident could not be determined. The manual further states: "Avoid uncoordinated use of the controls at the stalling speed as this may result in a spin. SPINS ARE PROHIBITED... There is evidence that permitting a spin to go beyond one turn without initiating proper recovery procedures can allow a spin mode to develop from which recovery is not possible."