CEN12FA594

While maneuvering in mountainous terrain at high density altitude conditions, the pilot impacted a ridge area. An evaluation of the terrain near the accident site and the performance capabilities of the airplane indicated that the pilot selected a route of flight toward rising terrain that the airplane could not climb sufficiently quickly to avoid. Examination of the airframe, engine, and propeller did not reveal any preimpact failures or malfunctions that would have precluded normal operation.

HISTORY OF FLIGHT On August 31, 2012, about 0920 mountain daylight time, a Piper PA-12, N3031M, co-owned by the pilot, was substantially damaged after impacting mountainous terrain near Rye, Colorado. The private pilot and passenger were fatally injured. The flight was conducted under the provisions of 14 Code of Federal Regulations Part 91, with no flight plan filed. Visual meteorological conditions prevailed. The flight departed Pueblo Memorial Airport (PUB), Pueblo, Colorado at about 0806. According to law enforcement witnesses, the pilot and passenger arrived overhead their planned surveillance location and established radio contact with law enforcement personnel stationed on the ground. These law enforcement personnel, as well as other witnesses, observed multiple passes of the airplane about 500 to 1,000 feet above ground level, followed by a maneuvering of the airplane towards the west and out of their sight. The airplane subsequently impacted terrain about two miles west of the surveillance area in a heavily wooded area at 10,171 feet. A postimpact fire ensued. PERSONNEL INFORMATION The pilot, age 64, held a private pilot certificate with an airplane single-engine land rating. On March 12, 2012, the pilot was issued a Class 3 medical certificate, valid until March 31, 2013. The certificate required corrective lenses be worn. At the time of the medical examination, the pilot reported having 900 hours of flight experience, with 50 hours in the last six months. A review of records indicates the pilot had flown about 140 hours in the accident airplane. The girlfriend of the pilot stated that the pilot was very familiar with mountain flying and flew frequently in the mountainous areas of Colorado, including near the Lake Isabel area where the accident occurred. AIRCRAFT INFORMATION The accident airplane, a 1947 Piper PA-12, was registered to Three Bushwhackers Incorporated LLC. An airworthiness certificate was issued for the airplane on February 23, 1956. The airplane was equipped with a Lycoming O-290-D2 135 horsepower engine, which had accumulated about 690 hours since last field overhaul. METEOROLOGICAL INFORMATION A Bureau of Land Management and United States Forest Service station (WLCC2) was located about 3 miles to the northeast of the accident site at an elevation of 9,053 feet. Observations from WLCC2 at 0856 identified a temperature of 64.0 degrees Fahrenheit (F), a dew point temperature of 26.5F, and a wind from the east-southeast at 3 knots with gusts to 5 knots. At 0956, WLCC2 identified a temperature of 67.0F, a dew point temperature of 25.8F, and a wind from the east-southeast at 5 knots with gusts to 10 knots. A station that was part of the Citizen’s Weather Observing Program (D0665) was located about 15 miles to the west-northwest of the accident site at an elevation of 8,514 feet. At 0918, D0665 reported an altimeter setting of 29.86 inches of mercury. Utilizing the altimeter setting from D0665, and a temperature of 65.5°Fand dew point temperature of 26.2°F (achieved from interpolating between the two WLCC2 observations), density altitude at 9,000 feet elevation was about 11,600 feet, and density altitude at the accident site elevation of 10,171 feet was about 13,000 feet. WRECKAGE AND IMPACT INFORMATION The airplane impacted into remote, wooded, mountainous terrain and was consumed by fire. The terrain surrounding the impact site had a significant slope and the impact heading was in the direction of the downslope, with trees uphill from the impact crater displaying freshly broken and cut tree limbs. During examination, the engine crankshaft was rotated by hand and a compression check was confirmed on all cylinders. Engine drive train continuity was established throughout the engine. Engine cylinders were borescope inspected and no anomalies were noted. Spark plugs appeared worn out-normal as compared to the Champion Aviation Check-a-Plug Chart AV-27. The oil pressure screen was found free of debris. Both magnetos were found deformed by heat and could not be rotated. The carburetor was mostly consumed by fire and only the throttle plate was found. The propeller was found still attached to the crankshaft. Both blades wear bent aft and exhibited chord-wise scratches and significant leading edge damage. Flight control system continuity was confirmed as normal. Examination of the airframe, engine and propeller did not reveal any anomalies associated with a pre impact failure or malfunction. MEDICAL AND PATHOLOGICAL INFORMATION On September 3, 2012, an autopsy was performed on the pilot by the El Paso County Coroner. The cause of death was attributed to blunt force injuries. The FAA's Civil Aeromedical Institute in Oklahoma City, Oklahoma, performed toxicology tests on the pilot. No ethanol or drugs were detected during testing. TESTS AND RESEARCH A study of climb capability for the accident airplane was performed by the NTSB Office of Research and Engineering (RE), utilizing data from the pilot operating handbook for an aircraft equipped with a Lycoming O-235-C, 100 horsepower (HP) engine, adjusted to account for the higher, 135 HP rating of the O-290-D2 engine installed on the accident aircraft. Based on excess power calculations, RE estimated climb rate and climb gradient for the accident airplane. Airplane weight at the time of the accident was estimated at 1600 pounds, based on a combined pilot and passenger weight of 425 pounds and estimated fuel weight at the time of the accident. At a density altitude of 13,000 feet and airplane weight of 1600 pounds, the climb rate capability was about 350 feet per minute, and the climb gradient capability was about 240 feet per mile. A table of climb rate and climb gradient estimates at various density altitude and aircraft weight combinations is located in the public docket. Terrain to the west of the surveillance area was evaluated for potential flight paths leading to the accident site. A valley to the west of Lake Isabelfollows the Saint Charles River for about a mile and then bends southwest. After this bend, the river valley elevation rises and continues toward a ridge area, with higher terrain on the left and right sides of the river valley. The accident site was located on the ridge area, at an elevation of 10,171 feet in an area where the terrain gradient exceeds 1000 feet per mile. Within one mile of the accident site, the ridge continues to climb to an elevation exceeding 11,400 feet. A chart and Google earth views of terrain near the accident site are located in the public docket.