Alon A2 accident near Laramie, Wyoming, September 11, 2015

The NTSB's narrative final · quoted from the NTSB record

The private pilot reported that, after departing and then making a slow circling climb to about 9,500 ft mean sea level (msl), the airplane was unable to climb any higher and was occasionally descending. The pilot began to fly on course toward higher terrain, and the engine suddenly began to lose power. The pilot applied carburetor heat, but engine power was not restored. The airspeed then slowed, and the airplane descended. The airplane impacted the concrete median barrier on the highway in a narrow mountain pass at an estimated terrain elevation of 7,980 ft msl and then came to rest upright. There was a fuel spill at the scene but no postimpact fire, and the injured pilot was able to exit the airplane without assistance. A postaccident examination of the airplane and engine found no preaccident mechanical malfunctions or failures that would have precluded normal operation. The pilot reported that the airplane had been recently fitted with a 4-point inertial reel shoulder harness system and that it is likely that his use of that shoulder harness system prevented him from sustaining a more serious injury. The weather conditions about the time of the accident were conducive to the accumulation of serious carburetor icing at all power settings. Federal Aviation Administration guidance states that, when conditions are conductive to carburetor icing, the pilot should immediately apply carburetor heat and that the heat should be left on until the pilot is certain that all of the ice has been removed. It is likely that the engine began to lose power due to carburetor ice and that the timely application of carburetor heat would have restored engine power.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.