Casualties unknown

2004-10-23: Cessna 170A (N9176A) — Glenwood Spring, CO

Glenwood Spring, CO, US

On October 23, 2004, a Cessna 170A (registration N9176A) was involved in an aviation accident near Glenwood Spring, CO. Investigators recorded the probable cause as: the pilot's failure to use carburetor heat which resulted in the formation of carburetor ice and the loss of engine power. Related factors were conditions conducive for carburetor icing and the lack of suitable terrain for a forced landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

A pilot reported that the engine did not respond to throttle application during a go-around, leading to a collision with a townhouse. The descent was made without carburetor heat in conditions conducive to serious icing.

Accident Sequence

The pilot reported that he had been flying for approximately one hour before the accident. He descended from about 8,500 feet mean sea level (msl) with an engine power setting of 2,200 rpm and without applying carburetor heat. The descent lasted 20 to 30 minutes as he flew from west to east for approximately 60 miles. After entering the traffic pattern at about 7,000 feet msl, he applied carburetor heat, enrichened the mixture "somewhat", and reduced power to approximately 1,500 to 1,700 rpm in preparation for landing.

On final approach, the pilot decided the aircraft was too high and added throttle to initiate a go-around. The engine did not respond to the throttle application. The airplane subsequently impacted the roof of a townhouse, slid down, and then struck the side of an adjacent townhouse, resulting in substantial damage to the aircraft.

Conditions

At the time of the accident, the aviation routine weather report (METAR) reported a temperature of 34 degrees Fahrenheit and a dewpoint of 31 degrees Fahrenheit. According to the carburetor icing chart, these conditions were conducive for "serious icing at cruise power." The pilot had not used carburetor heat during the extended descent.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20041027X01699. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.