NTSB Factual Report

On February 16, 2005, approximately 1500 mountain standard time, a Cessna 172 single-engine airplane, N3985F, piloted by an instrument-rated private pilot, was destroyed when it impacted trees and terrain following a partial loss of engine power while maneuvering near Montrose, Colorado. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under the provisions of Title 14 CFR Part 91, without a flight plan. The pilot sustained minor injuries. The cross-country flight originated in Bullhead City, Arizona, approximately 1200, and was destined for Montrose, Colorado.

According to local authorities, the pilot reported that he was en route to Montrose for 3 to 3.5 hours when the airplane approached Uncompahgre Plateau, approximately 30 miles southwest of Montrose. The pilot stated that the aircraft was not equipped for flight in instrument meteorological conditions, so he, "spotted a hole and dropped down and attempted to cross the mountain range." As the airplane neared the top of the mountain range, the engine began losing power. The pilot estimated that the engine had lost approximately seventy-five percent of its power and that he was too far into a canyon to reverse course. He then attempted an emergency landing into an area of trees, and subsequently, the airplane stalled and impacted the snow covered terrain. In addition, the pilot stated that "the aircraft did not have a lot of power to begin with and he has had icing problems in the past...he [believed] that icing is what caused his loss of power."

Local authorities, who responded to the accident site, reported the carburetor heat was found in the OFF position.

At 1453, the Montrose Regional Airport (MTJ), Montrose, Colorado, automated surface observing system (ASOS), located approximately 20 miles northeast of the accident site, reported the wind from 060 degrees at 4 knots, visibility 10 statute miles, scattered clouds at 1,000 feet, sky broken at 2,600 feet, temperature 37 degrees Fahrenheit, dew point 34 degrees Fahrenheit, and an altimeter setting of 30.12 inches of Mercury.

At 1508, MTJ ASOS reported the wind variable at 3 knots, visibility 10 statute miles, sky broken at 1,000 feet and 2,600 feet agl, temperature 37 degrees Fahrenheit, dew point 34 degrees Fahrenheit, and an altimeter setting of 30.12 inches of Mercury.

According to the Federal Aviation Administration (FAA) "Carburetor Icing Probability Chart," the atmospheric conditions at the time of the accident were conducive to "Serious Icing at Cruise Power."

According to the FAA Advisory Circular 20-113: Pilot precautions and procedures to be taken in preventing aircraft reciprocating engine induction system and fuel system icing problems, "The effect of throttle icing is a progressive decline in power delivered by the engine...If induction system ice is suspected of causing a power loss, apply full heat...Heat should be applied for a short time to warm the induction system before beginning a prolonged descent with the engine throttled and left on during the descent. Power lever advancement should be performed periodically during the descent to assure that power recovery can be achieved...the pilot should regularly use heat under conditions known to be conducive to atmospheric icing and be alert at all times for indications of icing in the fuel system."

NTSB Probable Cause

the pilot's improper in-flight planning during the descent which resulted in partial loss of engine power due to carburetor ice. Contributing factors were the pilot's failure to select carburetor heat during the descent and unsuitable terrain for the forced landing.