NTSB Factual Report

On September 11, 2015, about 0740 mountain daylight time, an Alon A2 Aircoupe, single-engine airplane, N6359V, impacted terrain during climb to cruise near Laramie, Wyoming. The pilot was seriously injured. The airplane sustained substantial damage to both wings and the fuselage. The airplane was registered to and operated by a private individual, as a 14 Code of Federal Regulations Part 91 personal flight. Day visual meteorological conditions (VMC) prevailed at the accident site and a flight plan had not been filed. The airplane departed Laramie Regional Airport (LAR), Laramie, Wyoming, about 0720 and was destined for North Platte Regional Airport (LBF), North Platte, Nebraska.

The pilot reported that after departing LAR he had circled near the airport to slowly climb to about 9,500 feet above mean sea level (msl). On reaching 9,500 ft. the airplane would not climb any higher and was occasionally descending. The pilot began to fly on course toward higher terrain when the engine suddenly began to lose power. The pilot applied carburetor heat, which had no effect. The airspeed slowed and the airplane descended. The pilot attempted to force land the airplane on a highway and reported that he lost sight of the highway just before impact. The airplane, traveling eastbound, impacted the concrete median barrier on the interstate highway in a narrow mountain pass at an estimated terrain elevation of 7,980 feet msl and came to rest upright on the shoulder of the westbound lane of traffic. Witnesses saw the crash and immediately called 9-1-1. There was a fuel spill at the scene, but no postimpact fire, and the injured pilot was able to exit the airplane without assistance. The pilot noted that the airplane had been recently fitted with a 4-point inertial reel shoulder harness system and he was certain that that shoulder harness system saved him from a much more serious injury.

A postaccident examination of the airplane and engine found no preimpact anomalies which would have prevented normal operation.

The nearest aviation weather reporting station was located at LAR, about 10 miles west from the accident site. At 0753, the LAR automated surface observing system reported the following weather conditions: wind 180 degrees at 7 knots, visibility 10 miles, clear of clouds, temperature 8 degrees Celsius (C), dew point 6 degrees C, and an altimeter setting of 30.39 inches of Mercury. Data from the National Oceanic and Atmospheric Administration showed that, at the accident location, at 0750, the altitude of the sun was about 13 degrees above the horizon and the azimuth of the sun was about 095 degrees. Apparent sunrise occurred at 0638.

The carburetor icing probability chart from Federal Aviation Administration (FAA) Special Airworthiness Information Bulletin (SAIB): CE-09-35 Carburetor Icing Prevention, June 30, 2009, shows a probability of serious icing at all power settings at the temperature and dew point reported at the time of the accident.

ADDITIONAL INFORMATION:

The FAA Pilot's Handbook of Aeronautical Knowledge states that when conditions are conductive to carburetor icing that carburetor heat should be applied immediately and should be left on until the pilot is certain all the ice has been removed. Additionally, if ice is present the application of partial carburetor heat or leaving heat on for an insufficient time might aggravate the situation.

NTSB Probable Cause

The pilot’s failure to use carburetor heat in cruise flight while operating in an area conducive to serious carburetor icing, which resulted in a loss of engine power and an off-airport landing. Contributing to the accident was the pilot's decision to continue flight toward rising mountainous terrain when the airplane could not maintain altitude.