# NTSB DEN06CA088: Grumman-Schweizer G-164A, N9709, Cokeville, WY, June 14, 2006 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Data collection · Final report - Date: June 14, 2006, 10:30 local (16:30 UTC) - Place: Cokeville, WY - Coordinates: 42.034442, -110.951385 - Nearby events: https://openairdocs.org/map.md?lat=42.0344&lon=-110.9514&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report October 3, 2006 - Report: Approved by Office Director - Parties: FAA Flight Standards Field Office - NTSB case key (mKey): 63910 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN06CA088 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/63910/pdf - Page: https://openairdocs.org/ntsb/DEN06CA088 ## Probable cause the pilot's failure to maintain directional control resulting in a ground loop. Contributing factors included the high winds and crosswind. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight encounter with weather, landing - roll - weather condition - crosswind (contributing factor) - weather condition - high wind (contributing factor) - Loss of control - on ground/water, landing - roll - directional control - not maintained, pilot in command (cause) - ground loop/swerve - encountered, pilot in command (contributing factor) - In flight collision with terrain/water, landing - roll - terrain condition - ground ## Analysis According to the pilot, he was returning to the airport due to an approaching thunderstorm. During the landing roll the airplane encountered a gust of wind and ground looped. Both wings separated, the propeller was bent, and the horizontal stabilizer was crushed and wrinkled. The pilot reported no anomalies with the airframe or airplane systems. The routine aviation weather report reported, winds, 230 degrees at 25 knots, gusting 31 knots. The pilot estimated the gust of wind at 40 knots. ## Factual narrative According to the pilot, he was returning to the airport due to an approaching thunderstorm. The pilot entered traffic for runway 15, and while on final, noticed that the wind had shifted to favor runway 33. During the landing roll to runway 33 (3,400 feet by 60 feet, asphalt), the airplane encountered a gust of wind and the airplane ground looped. Both wings separated, the propeller was bent, and the horizontal stabilizer was crushed and wrinkled. The pilot reported no anomalies with the airframe or airplane systems. The closest official weather observation station was Uninta County Airport/Burns Field (EVW), Evanston, Wyoming, located 45 nautical miles south of the accident site. The routine aviation weather report (METAR) for EVW, issued at 1053, reported, winds, 230 degrees at 25 knots, gusting 31 knots. The pilot estimated the gust of wind at 40 knots. ## Aircraft - Registration: [N9709](https://openairdocs.org/aircraft/N9709), registered now, S/N 1233, built 1974 (OpenAirDocs) - Reported make and model: Grumman-Schweizer G-164A - Registry model: [Grumman Acft ENG Cor-Schweizer G-164A](https://openairdocs.org/model/grumman-acft-eng-cor-schweizer-g-164a) (registry code 3952801) (OpenAirDocs) - Registry engine: [Pratt & Whitney R1340 series](https://openairdocs.org/engine/pratt-whitney-r1340-series) (registry code 52016, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 1233 - Airframe hours: 5910 - Engines: Honeywell TPE 331-2-201 600 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, May 1, 2006 - Departed: U06, COKEVILLE, WY - Destination: U06, Cokeville, WY - Airport: U06, Cokeville Municipal Airport, runway 33, 3,400 × 60 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; injuries: minor; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review May 1, 2006; seat: front; flight hours: 10,913 total, 250 in this make and model, 10,713 as pilot in command, 200 in the last 90 days, 50 in the last 30 days, 10 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 230° at 25 knots, gusting 31 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 61 °F, dew point 32 °F - Altimeter: 30.01 inHg - Observed at: EVW, 45 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 20060614010139A](https://openairdocs.org/incident/20060614010139A), Jun 14, 2006: Scwzer G164A, Cokeville, WY, Substantial damage. (-23) Airman was applying mosquito spray in the Cokeville, Wyoming area. A fast moving cold front with embedded thunderstorms was moving through the area.… ## Other investigations on N9709 (1) 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. - [NTSB WPR24FA213](https://openairdocs.org/ntsb/WPR24FA213), Jun 25, 2024: Grumman Acft ENG Cor-Schweizer G-164A (N9709), Chamberino, NM, destroyed, 1 fatal. Probable cause: An aerodynamic stall and loss of control for reasons that could not be determined based on the available information. 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.