# NTSB GAA16CA393: Cessna 188, N9979G, What Cheer, IA, July 25, 2016 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: July 25, 2016, 18:00 local (23:00 UTC) - Place: What Cheer, IA - Coordinates: 41.427776, -92.377777 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.4278&lon=-92.3778&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report December 5, 2016 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA - NTSB case key (mKey): 93693 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA16CA393 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93693/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=93693 - Page: https://openairdocs.org/ntsb/GAA16CA393 ## Probable cause The loss of engine power for undetermined reasons due to the pilot not making the airplane or engine available for examination, which resulted in a forced landing and an impact with terrain. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Cessna 188A, 1 case](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=2073006), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) - [Terrain: rough terrain](https://openairdocs.org/ntsb-findings/03021015): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Cessna 188A, 1 case](https://openairdocs.org/ntsb-findings/03021015/cases.md?model=2073006), [All aircraft, 442 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md) - [Temp/humidity/pressure: conducive to carburetor icing](https://openairdocs.org/ntsb-findings/03031030): Environmental issues › Conditions/weather/phenomena · Not specified; cases with it: [Cessna 188A, 1 case](https://openairdocs.org/ntsb-findings/03031030/cases.md?model=2073006), [All aircraft, 435 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md) - [Ice/rain protection system: intake anti-ice, deice](https://openairdocs.org/ntsb-findings/01023020): Aircraft › Aircraft systems · Not used/operated; cases with it: [Cessna 188A, 1 case](https://openairdocs.org/ntsb-findings/01023020/cases.md?model=2073006), [All aircraft, 108 cases](https://openairdocs.org/ntsb-findings/01023020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Cessna 188A, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=2073006), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Cessna 188A, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=2073006), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that he was performing "practice" aerial application operations at 30 feet above the ground and the engine slowly lost power. He further reported that he made a left turn and landed in a bean field, which resulted in substantial damage to the right wing and left elevator. During postaccident interviews with the pilot, he reported that immediately before the loss of engine power he was flying wings level, the mixture was forward (full rich), and the power was set to a cruise setting. He further reported that the carburetor heat was off for the entirety of the flight. The pilot reported that the loss of engine power was gradual and there was no visible oil spray over the windscreen. He reported that immediately after the accident he checked the oil level and found no anomalies. During a postaccident examination, an airframe and powerplant mechanic reported that he drained 13 gallons of fuel from the single fuel tank. He further reported that he observed the float carburetor and gascolater, both were unremarkable. He also reported that the propeller could be rotated in a normal manner. The Federal Aviation Administration Pilot's Handbook of Aeronautical Knowledge (PHAK) states in part: "Carburetor ice occurs due to the effect of fuel vaporization and the decrease in air pressure in the venturi, which causes a sharp temperature drop in the carburetor. If water vapor in the air condenses when the carburetor temperature is at or below freezing, ice may form on internal surfaces of the carburetor, including the throttle valve." The PHAK further states: "If enough ice builds up, the engine may cease to operate. Carburetor ice is most likely to occur when temperatures are below 70 degrees Fahrenheit (°F) or 21 degrees Celsius (°C) and the relative humidity is above 80 percent. Due to the sudden cooling that takes place in the carburetor, icing can occur even in outside air temperatures as high as 100 °F (38 °C) and humidity as low as 50 percent. This temperature drop can be as much as 60 to 70 absolute (versus relative) Fahrenheit degrees (70 x 100/180 = 38.89 Celsius degrees)." An automated weather observing system about the time of the accident 13 nautical miles northeast of the accident site reported a temperature of 81 degrees Fahrenheit (27 Celsius) and a dew point 66 degrees Fahrenheit (19 Celsius). According to a carburetor-icing-probability chart, the engine was at risk of "moderate icing" at cruise power. The airplane manufacturer owner's manual in part states: "In atmospheric conditions that are conducive to carburetor icing, select the minimum amount of carburetor heat for normal operation that will keep ice cleared from the carburetor." It is likely that the loss of engine power was due to carburetor ice, however, the pilot, who was also the airplane owner, did not make the airframe or engine available for examination by the National Transportation Safety Board. ## Factual narrative The pilot reported that he was performing "practice" aerial application operations at 30 feet above the ground and the engine slowly lost power. He further reported that he made a left turn and landed in a bean field, which resulted in substantial damage to the right wing and left elevator. During postaccident interviews with the pilot, he reported that immediately before the loss of engine power he was flying wings level, the mixture was forward (full rich), and the power was set to a cruise setting. He further reported that the carburetor heat was off for the entirety of the flight. The pilot reported that the loss of engine power was gradual and there was no visible oil spray over the windscreen. He reported that immediately after the accident he checked the oil level and found no anomalies. During a postaccident examination, an airframe and powerplant mechanic reported that he drained 13 gallons of fuel from the single fuel tank. He further reported that he observed the float carburetor and gascolater, both were unremarkable. He also reported that the propeller could be rotated in a normal manner. The Federal Aviation Administration Pilot's Handbook of Aeronautical Knowledge (PHAK) states in part: "Carburetor ice occurs due to the effect of fuel vaporization and the decrease in air pressure in the venturi, which causes a sharp temperature drop in the carburetor. If water vapor in the air condenses when the carburetor temperature is at or below freezing, ice may form on internal surfaces of the carburetor, including the throttle valve." The PHAK further states: "If enough ice builds up, the engine may cease to operate. Carburetor ice is most likely to occur when temperatures are below 70 degrees Fahrenheit (°F) or 21 degrees Celsius (°C) and the relative humidity is above 80 percent. Due to the sudden cooling that takes place in the carburetor, icing can occur even in outside air temperatures as high as 100 °F (38 °C) and humidity as low as 50 percent. This temperature drop can be as much as 60 to 70 absolute (versus relative) Fahrenheit degrees (70 x 100/180 = 38.89 Celsius degrees)." An automated weather observing system about the time of the accident 13 nautical miles northeast of the accident site reported a temperature of 81 degrees Fahrenheit (27 Celsius) and a dew point 66 degrees Fahrenheit (19 Celsius). According to a carburetor-icing-probability chart, the engine was at risk of "moderate icing" at cruise power. The airplane manufacturer owner's manual in part states: "In atmospheric conditions that are conducive to carburetor icing, select the minimum amount of carburetor heat for normal operation that will keep ice cleared from the carburetor." It is likely that the loss of engine power was due to carburetor ice, however, the pilot, who was also the airplane owner, did not make the airframe or engine available for examination by the National Transportation Safety Board. ## Aircraft - Registration: [N9979G](https://openairdocs.org/aircraft/N9979G), registered now, S/N 18800779, built 1971 (OpenAirDocs) - Reported make and model: CESSNA 188 (A) - Registry model: [Cessna 188A](https://openairdocs.org/model/cessna-188a) (registry code 2073006) (OpenAirDocs) - Registry engine: [Continental O-470R](https://openairdocs.org/engine/continental-o-470r) (registry code 17071, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18800779 - Year built: 1971 - Airframe hours: 5344 - Engines: Continental O-470-U 250 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, July 1, 2016 - Departed: NONE, Gibson, IA - Destination: NONE, Gibson, IA - Equipment: Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; injuries: none; private; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; last flight review January 13, 2015; seat: single; restraint: 5-point; flight hours: 1,313 total, 34 in this make and model, 1,252 as pilot in command, 58 in the last 90 days, 27 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 20° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 66 °F - Altimeter: 30.03 inHg - Observed at: KOOA, 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 20160725016849A](https://openairdocs.org/incident/20160725016849A), Jul 25, 2016: Cessna 188A, What Cheer, IA, Substantial damage. In late afternoon on the day of the crash, the pilot performed a preflight inspection, an engine run up and took off from his private farm airstrip to practice… ## Docket (6 files) The files NTSB released with the investigation on October 5, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=93693. 1.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 274 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444989&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Conversations (Pilot in Command) (item 2, .PDF, 71 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444990&FileExtension=.PDF&FileName=Record%20of%20Conversations%20(Pilot%20in%20Command)-Master.PDF - Record of Conversation (Mechanic) (item 3, .PDF, 59 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444991&FileExtension=.PDF&FileName=Record%20of%20Conversation%20(Mechanic)-Master.PDF - Carburetor-Icing-Probability Chart (item 4, .PDF, 119 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444992&FileExtension=.PDF&FileName=Carburetor-Icing-Probability%20Chart-Master.PDF - Cessna Owner Manual Engine Controls (item 5, .PDF, 58 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444993&FileExtension=.PDF&FileName=Cessna%20Owner%20Manual%20Engine%20Controls-Master.PDF - Accidents Photos (Courtesy of FAA) (item 6, .PDF, 2 photos, 628 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40444994&FileExtension=.PDF&FileName=Accidents%20Photos%20(Courtesy%20of%20FAA)-Master.PDF 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.