N46603Cessna 172K · 1968

On March 18, 2014, about 1930 eastern daylight time, a Cessna 172K airplane, N46603, was substantially damaged after it impacted mountainous terrain in Elizabethton Municipal Airport (0A9), Elizabethton, Tennessee. The private pilot and a passenger sustained serious injuries and another passenger received minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the flight, which originated from 0A9 about 1915 and was destined for Weltzien Skypark (15G), Wadsworth, OH. The personal flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91.

According to the pilot, he departed 15G three days prior to the accident to fly a family friend to South Carolina. The pilot originally intended to return to 15G the following day, but was delayed due to weather. On the day of the accident, the pilot and his passengers left South Carolina bound for 15G. The pilot made an unscheduled stop for fuel at 0A9, after discovering the fuel services at his intended airport were closed. After refueling at 0A9 he departed runway 06 and flew the airport traffic pattern. He maintained an altitude of 500 feet above ground level (agl) and exited the traffic pattern on the left downwind leg on a course direct towards Holston Mountain. The pilot followed the upslope of the mountain at a 500 feet per minute rate of climb. Concerned that the airplane would not clear the approaching terrain, the pilot decided to turn the airplane towards a small valley to his right that appeared to have a lower terrain elevation. During the turn the airplane descended, impacted trees and then terrain before coming to rest.

During the pilot's interview with a Federal Aviation Administration (FAA) inspector and the NTSB investigator-in-charge, the pilot stated he should have "gained more altitude" before starting his climb over the mountain. In an interview with an FAA inspector the pilot was asked if he had any mechanical issues with the aircraft, to which the pilot replied "No."

According to the pilot and FAA records, he held a private pilot certificate for airplane single-engine land. The pilot's most recent third-class medical certificate was issued on May 4, 2013. The pilot reported 90 hours of total flight experience, of which 10 hours were in the accident airplane make and model.

The airplane was manufactured in 1968 and was equipped with a Lycoming O-320-E2D, 150-hp, carbureted reciprocating engine. According to maintenance records, the airplane's most recent 100-hour inspection was completed on November 20, 2013. The airplane's most recent engine overhaul was completed on September 9, 2007. At the time of the accident, the engine had accumulated 6,688 hours of total time in service, and 61 hours of time in service since the most recent inspection.

The 1856 recorded weather at 0A9, located about 3 nautical miles south of the accident site, included calm wind, clear skies, 10 miles visibility, temperature 13 degrees C, dewpoint 4 degrees C, and an altimeter setting of 29.95 inches of mercury.

The airplane was manufactured in 1968 and was equipped with a Lycoming O-320-E2D, 150-hp, carbureted reciprocating engine. According to maintenance records, the airplane's most recent 100-hour inspection was completed on November 20, 2013. The airplane's most recent engine overhaul was completed on September 9, 2007. At the time of the accident, the engine had accumulated 6,688 hours of total time in service, and 61 hours of time in service since the most recent inspection.

According to information provided by the FAA and the airframe manufacturer, the airplane came to rest on its left side about 3000 feet above mean sea level (msl) in a wooded area and was oriented on a 221 degree heading, the debris path was oriented on a 141 degree heading. All major components of the airplane were accounted for at the accident site. A section of the fuselage was bent downward and partially separated just aft of the main cabin. The vertical stabilizer and left horizontal stabilizer remained attached to the empennage, which was co-located with the main wreckage. The right horizontal stabilizer was located about 200 ft. from the main wreckage with the elevator attached. Both wings remained attached to the fuselage and sustained leading edge crush damage along their entire length. The right wing was bent in the positive direction about 45 degrees. Both propeller blades remained attached to the hub. One blade exhibited S-bending with some polishing and chordwise scratching. The outboard section of another propeller blade was bent and the tip was fractured and separated.

The airframe was examined at the accident site by a representative of the airframe manufacturer under the supervision of a FAA inspector. Control continuity was traced from the cockpit area to each of the flight control surfaces. The flap actuator measured 0 degrees, which was consistent with a flaps retracted positon.

The engine was recovered to a secure facility in Springfield, Tennessee and a follow-up engine examination took place on May 5, 2014 and supervised by a NTSB investigator. Continuity of the engine's crankshaft and valvetrain were confirmed through rotation at the vacuum pump drive pad, and thumb compression was confirmed on all cylinders. The top and bottom spark plugs were removed and inspected; the top plugs and two of the bottom plugs exhibited normal wear and two of the bottom plugs were oil soaked. Both magnetos rotated freely by hand and exhibited normal sparking on all leads.

The fuel strainer contained fuel and the strainer screen was free of debris. The carburetor fuel inlet screen was free of debris and no fuel stains were present on the carburetor surfaces.

Airplane Performance

The distance between the airport pattern and the top of the mountain is about 1.8 nautical miles (nm) and the elevation at the top of the mountain is about 3,000 feet msl. Based on the values reported by the pilot, at 78 knots the airplane would have travelled to the top of the mountain, 1.8nm, in 1 minute 23 seconds; however, at a 500 feet per minute climb rate, the airplane required 1 minute 48 seconds of flight time to reach the 3,000 foot mountain peak. Density altitude at the airport around the time of departure was about 1,800 feet.

Research

According to the FAA publication "Tips on Mountain Flying"(FAA-P-8740-60, AFS-803), "a normally aspirated engine will lose 3% of its power per thousand feet of density altitude increase. Next, as density altitude increases, the wings have less dense air which to create lift. Since a propeller is an airfoil, it, too, will be less efficient." The FAA also recommends that pilots cross mountain passes at an altitude at least 1000 feet above the pass elevation.