History of Flight
On January 31, 2011, at approximately 1525 Pacific standard time, a Cessna 172, registration N6922A, collided with mountainous terrain near Glendora, California, while maneuvering. The aircraft was substantially damaged. The flight instructor, who was also the owner, sustained serious injuries, and the commercial pilot receiving instruction suffered minor injuries. The flight was conducted under 14 Code of Federal Regulations Part 91 as a local instructional flight that had originated from Brackett Field (POC) in La Verne, California, about 2 hours 30 minutes prior. No flight plan was filed, and visual meteorological conditions prevailed.
According to the flight instructor, the training mission aimed to provide the student with experience flying a tail wheel-equipped airplane in mountainous terrain. After approximately 2 hours of traffic pattern work involving touch-and-go landings, the flight proceeded to a local practice area for air work. Due to air traffic congestion, they relocated to more mountainous terrain to practice utilizing orographic lift.
The instructor reported that the lift they were experiencing began to dissipate. He took control of the aircraft, added full power to exit the area, and then encountered a strong downdraft. Moments later, the airplane impacted the terrain. Rescue teams arrived, and due to the steepness of the terrain, a helicopter was used to evacuate the two injured occupants. At the time of rescue, the flight instructor informed local authorities that “they had no problems with the airplane.”
Personnel Information
The 53-year-old flight instructor held a second-class FAA medical certificate issued on February 2, 2010. He possessed a flight instructor certificate with a single-engine land airplane rating, a commercial pilot certificate with single-engine and multi-engine land airplane ratings, and an instrument airplane rating. He estimated his total flight experience at approximately 1,800 hours.
The 37-year-old commercial pilot receiving instruction held a second-class FAA medical certificate issued on January 7, 2010. He held a commercial pilot certificate with a single-engine land airplane rating. At the time of rescue, he told authorities he had approximately 300 hours of flight experience.
Aircraft Information
The airplane was a 1956 Cessna 172, a single-engine, propeller-driven, four-seat aircraft with dual flight controls. It had been converted from a tricycle landing gear configuration to a tail wheel landing gear configuration. The maximum takeoff gross weight was 2,300 pounds. It was powered by a Continental O-300-A reciprocating, direct-drive, air-cooled, normally aspirated engine with a maximum takeoff rating of 145 horsepower at sea level. Maintenance records indicated the last 100-hour inspection was performed on January 30, 2011.
Meteorological Information
At 1553, weather conditions at Chino, California (located 130 degrees at 16 nautical miles from the accident site) were reported as: wind from 260 degrees at 8 knots; visibility 10 statute miles; few clouds at 4,000 feet and scattered clouds at 25,000 feet; temperature 63°F; dew point 45°F; altimeter setting 30.09 inches of mercury.
Wreckage and Impact Information
The wreckage was located approximately 400 feet below a ridge line at an elevation of 2,300 feet, on steep terrain. A ground scar of about 100 degrees led to the wreckage. The nose of the airplane was compressed aft and upward into the cockpit. The fuselage just forward of the empennage was compressed and wrinkled; both horizontal stabilizers were bent and wrinkled. Half of the left elevator was torn away, and both wings were bent and wrinkled.
An airframe and engine examination conducted on February 9, 2011, by an NTSB Senior Air Safety Investigator and representatives from the airframe and engine manufacturers confirmed flight control cable continuity for all controls, though several cables had been cut for aircraft recovery. The propeller assembly remained attached to the crankshaft. Upper spark plugs were removed and exhibited normal wear. The crankshaft rotated freely, and thumb compression was observed in proper order on all six cylinders. Mechanical continuity was established throughout the rotating group, valve train, and accessory section during hand rotation of the propeller. No evidence of preimpact mechanical anomalies that would have precluded normal operation was found in the airframe or engine.