WPR11LA201 · Cessna 172S

The private pilot and his passenger departed on a flight to an airport with an elevation of 5,157 feet mean sea level (msl), and a density altitude of about 6,200 feet. Although the pilot had received classroom instruction on high elevation airport, high density altitude operations, the flight was his first to a high elevation airport, and he planned to conduct his first landing there as a touch-and-go. After touchdown, the pilot retracted the flaps, applied full throttle, and lifted off. The pilot perceived that the airplane was underperforming on the climbout, and he enriched the fuel-air mixture, which did not rectify the problem. The engine was making "popping" sounds, the airspeed was lower than normal, and the tachometer indicated about 500 rpm less than the target value. The pilot began a right turn back toward the airport, and lowered the airplane’s nose to increase airspeed, but the airplane entered a spin and impacted terrain. Postaccident examination of the airframe and engine did not reveal any preimpact mechanical failures or malfunctions that would have precluded normal operation.

Review of the pilot's history revealed that he received all his training and flight experience through a flight school that was based at an airport with an elevation of about 1,500 feet msl. The pilot's full enrichment of the mixture for the takeoff and climbout at the destination airport was contrary to the procedure published in the airplane manufacturer's Pilot's Operating Handbook, which stated that the mixture was to be leaned for maximum rpm. Considering the dynamic conditions and limited time available to ensure proper mixture adjustment during a touch-and-go landing at a high-elevation airport, and the effect of an improper mixture on airplane climb capability at such an airport, the pilot deprived himself of potential safety margins by deciding to conduct his arrival as a touch and go. His lack of any prior operations at high elevation airports further reduced his safety margin by depriving him of applicable experience. Subsequent to the accident, the pilot’s flight school implemented several new policies regarding operations at high elevation airports, including a prohibition against pilots operating solo at such airports until they have done so with a flight instructor.

Verbatim NTSB analysis and probable cause from the NTSB dataset