IAD96LA053
IAD96LA053

On March 21, 1996, at 1908 eastern standard time, a Cessna 172, N108RV, struck a parked car and a tree during a forced landing in a shopping mall parking lot in Roanoke, Virginia. The pilot and the one passenger reported no injuries. The airplane sustained substantial damage. Visual meteorological conditions prevailed for the flight, and a Visual Flight Rules (VFR) flight plan was filed. The business flight was conducted under 14 CFR Part 91. The flight originated in Hickory, North Carolina, at approximately 1740, with an intended destination of Bedford, Pennsylvania.

The pilot stated that about an hour after he departed Hickory, North Carolina, the engine started to run rough. He said that he checked the fuel mixture, engine RPM, and applied full carburetor heat. The pilot indicated that he left the carburetor heat on for 3 to 4 minutes, then turned the carburetor heat off. According to the pilot, approximately thirty minutes later, the airplane was in cruise flight at 11,500 feet mean sea level (MSL) when the engine RPM began to decrease.

The pilot reported that when the engine lost power, he applied full carburetor heat, and checked the airplane's position in relation to the nearest airport with the Global Positioning System (GPS) receiver. The pilot stated that the GPS receiver indicated that the Roanoke Regional Airport was 9.8 miles away on a 330 degree heading. The pilot reported he did not perform a complete restart checklist procedure and he did not confirm the position of the fuel selector valve.

At 1902, the pilot contacted Roanoke air traffic control (ATC), advised them that the airplane had lost engine power, and requested an emergency landing at Roanoke. Roanoke ATC cleared the pilot for a straight-in approach to runway 33. The pilot stated that he had the runway in sight from a distance of nine miles and maintained ninety knots indicated airspeed (KIAS) throughout the approach. According to the pilot, the engine produced partial power until the airplane was 2.5 miles from the airport, then it "...lost total engine power." He stated that when the airplane was approximately one half mile from the airport at 2,500 feet MSL, he realized that he was not going to reach the runway. The pilot indicated that he made a left turn, and tried to land in the shopping mall parking lot "...because of the good lighting." The left wing of the airplane struck a light pole and a parked vehicle. Roanoke field elevation is 1176 feet MSL.

The FAA controller who handled the airplane throughout the approach, stated: "The aircraft reported the lights in sight at six miles and I issued the wind and a landing clearance. The aircraft continued a rapid descent and crash landed approximately one-half mile from the end of runway 33." The controller said that he became concerned when he noticed a significant loss of altitude as the airplane approached the runway. The airplane had descended from an altitude of 6,300 feet at six miles to 3,500 feet at a distance of three miles.

The Cessna Pilot's Operating Handbook for the accident airplane states, "After an engine failure in flight, the best glide speed (65 KIAS) should be established as quickly as possible." The 65 KIAS best glide speed provides a glide ratio of 9:1. A representative of the Cessna aircraft company stated that at 90 KIAS the glide ratio is 8:1.

A postaccident inspection of the aircraft by Federal Aviation Administration (FAA) inspectors revealed no evidence of preimpact anomalies. The fuel appeared to be free of contamination and the carburetor heating system was determined to be mechanically sound and operational. A postaccident engine test run was completed, with no problems noted.

The FAA Inspector stated, "We were unable to determine a firm cause for the engine stoppage, but either carburetor ice or fuel mismanagement (while switching from 'aux' to 'both') might have been a factor. He was cruising at 12,500 ft, where hypoxia might have become a factor, preventing him from recognizing the onset of carburetor icing in a timely fashion, or causing him to select the fuel to 'OFF', instead of 'BOTH'. The FAA inspector's report further noted that, "From 12,500 feet, 10 miles from the airport, the pilot still failed to make the runway (ROA field elevation is 1176)."

A carburetor icing probability chart prepared by the FAA, is appended. (DOT/FAA/CT-82/44 Publication: Light Aircraft Piston Engine Carburetor Ice Detector/Warning Device Sensitivity/Efectiveness, June 1982).

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