# NTSB DEN99LA057: Cessna 172G, N1321F, Agate, CO, March 19, 1999 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: March 18, 1999, 21:38 local (Mar 19, 1999, 04:38 UTC) - Place: Agate, CO - Coordinates: 39.469158, -103.949157 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.4692&lon=-103.9492&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed, report April 25, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 45932 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN99LA057 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/45932/pdf - Page: https://openairdocs.org/ntsb/DEN99LA057 ## Probable cause The development of carburetor ice resulting in a partial loss of engine power. Factors were the weather conditions favorable for carburetor icing, the dark night conditions, and the lack of suitable terrain for landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - nonmechanical, cruise - weather condition - carburetor icing conditions (contributing factor) - fuel system,carburetor - ice (cause) - Forced landing, descent - emergency - In flight collision with terrain/water, emergency descent/landing - terrain condition - open field - terrain condition - rough/uneven - terrain condition - none suitable (contributing factor) - light condition - dark night (contributing factor) ## Analysis While in cruise flight at 8,500 feet in dark night conditions, the aircraft's engine began experiencing a gradual loss of rpm. The pilot adjusted the mixture setting and applied carburetor heat, but was unsuccessful in restoring full power. She attempted to divert to the Limon, Colorado, Airport, 14 nautical miles to the east, but the aircraft was unable to maintain altitude. The airplane impacted the ground, became airborne, then hit the ground again in a rough, open field. The aircraft then nosed over. Two examinations on the engine and airframe were performed and no mechanical engine abnormalities or discrepancies were found. According to reported weather conditions at Limon, the closest weather facility located 14 miles from the accident site, the temperature and dew point were 30 and 25 degrees F., respectively, with overcast ceilings at 2,500 feet. According to a carburetor icing chart, the conditions near the time of the accident were conducive to the formation of moderate to severe icing with a cruise power setting. ## Factual narrative On March 18, 1999, at 2138 mountain standard time, a Cessna 172G, N1321F, owned and operated by the pilot, was substantially damaged during a forced landing following a partial loss of engine power while in cruise flight near Agate, Colorado. The private pilot and one passenger received minor injuries. The aircraft was being operated as a personal cross-county flight under Title 14 CFR Part 91, and no flight plan was filed. The flight originated from Kit Carson County Airport, Burlington, Colorado, at 2100, and was en route to Centennial Airport, Englewood, Colorado. Visual meteorological conditions prevailed. According to the pilot, she had stopped in Burlington to "top off" the fuel tanks. Approximately 40 minutes after departure, while level at 8,500 feet, she noted a gradual loss of rpm, followed by an "incipient loss of altitude." She stated that she adjusted the mixture setting and applied carburetor heat, but was unsuccessful in restoring full power. In dark night conditions, she attempted to divert to the Limon Airport, located 14 nautical miles to the east, but was unable to maintain altitude. She recalled crossing a road "at a very low altitude, and soon thereafter hit the ground" in a rough, open field. The airplane became airborne, then contacted the ground a second time. Upon impact, the aircraft nosed over. The aircraft sustained damage to the nose landing gear and the vertical stabilizer. On March 26, 1999, examinations of the engine and airframe were performed at Beegles Aircraft Services in Greeley, Colorado, with the assistance of engineering representatives from Teledyne Continental Motors and the Cessna Aircraft Company. A second inspection of the engine was accomplished on April 6, 1999, in which the engine was completely disassembled and examined. During both inspections, no mechanical engine abnormalities or discrepancies were found. 90 degree chordwise striations were observed on the cambered surface of one of the propeller blades. In addition, the spark plugs and piston domes were black in color. According to reported weather conditions at Limon, the closest weather facility located 14 nautical miles from the accident site, the temperature and dew point were 30 and 25 degrees F., respectively, with overcast ceilings at 2,500 feet. According to a carburetor icing chart (see attached), the conditions near the time of the accident were conducive to the formation of moderate to severe carburetor icing with a cruise power setting. ## Aircraft - Registration: [N1321F](https://openairdocs.org/deregistered/N1321F-2000-08-30), registration cancelled 2000-08-30, S/N 17254816 (OpenAirDocs) - Reported make and model: Cessna 172G - Registry model: [Cessna 172G](https://openairdocs.org/model/cessna-172g) (registry code 2072420) (OpenAirDocs) - Category: Airplane - Serial number: 17254816 - Airframe hours: 3458 - Engines: Continental O-300-D 145 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Lottie K. Theut - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 3, 1998, 114 hours before - Departed: ITR, BURLINGTON, CO - Destination: APA, ENGLEWOOD, CO ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 57; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 1,213 total, 1,181 in this make and model, 1,109 as pilot in command, 31 in the last 90 days, 22 in the last 30 days, 14 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night/dark - Wind: 170° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: 2,500 ft overcast - Temperature: 30 °F, dew point 25 °F - Altimeter: 30.00 inHg - Observed at: LIC, 13 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19990318040559A](https://openairdocs.org/incident/19990318040559A), Mar 18, 1999: Cessna 172G, Agate, CO, No damage. (-23) On March 18, 1999, at 2131 MST, a Cessna 172G, N1321F, owned and operated by the pilot, was substantially damaged during a forced landing following loss… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.