# NTSB GAA17CA488: Charles D Walker Walker Curtiss JN4D, N8262, Bowling Green, KY, August 12, 2017 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Data collection · Final report - Date: August 12, 2017, 11:00 local (16:00 UTC) - Place: Bowling Green, KY - Coordinates: 36.966945, -86.419166 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.9669&lon=-86.4192&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Loss of control in flight](https://openairdocs.org/ntsb-events/240) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report December 15, 2017 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA - NTSB case key (mKey): 95820 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA17CA488 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95820/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95820 - Page: https://openairdocs.org/ntsb/GAA17CA488 ## Probable cause The pilot’s exceedance of the biplane’s critical angle of attack during initial climb, which resulted in an aerodynamic stall and collision with trees. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: angle of attack](https://openairdocs.org/ntsb-findings/01062042): Aircraft › Aircraft oper/perf/capability · Capability exceeded (probable cause); cases with it: [Charles D Walker WALKER CURTISS JN4D, 1 case](https://openairdocs.org/ntsb-findings/01062042/cases.md?model=05632UK), [All aircraft, 990 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Charles D Walker WALKER CURTISS JN4D, 1 case](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=05632UK), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Object/animal/substance: tree(s)](https://openairdocs.org/ntsb-findings/03022020): Environmental issues › Physical environment · Effect on operation; cases with it: [Charles D Walker WALKER CURTISS JN4D, 1 case](https://openairdocs.org/ntsb-findings/03022020/cases.md?model=05632UK), [All aircraft, 933 cases](https://openairdocs.org/ntsb-findings/03022020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Charles D Walker WALKER CURTISS JN4D, 1 case](https://openairdocs.org/ntsb-events/240/sequence.md?model=05632UK), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Initial climb: Attempted remediation/recovery](https://openairdocs.org/ntsb-events/060); cases with it: [Charles D Walker WALKER CURTISS JN4D, 1 case](https://openairdocs.org/ntsb-events/060/sequence.md?model=05632UK), [All aircraft, 1,422 cases](https://openairdocs.org/ntsb-events/060/sequence.md) - [Initial climb: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Charles D Walker WALKER CURTISS JN4D, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=05632UK), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot of the experimental, amateur-built biplane reported that, following a normal initial climb, about 100 ft above the ground, the biplane started an uncommanded left turn, followed by a descent. He added that it became apparent that the flightpath was into the tree line, and he "attempted to climb to possibly maintain at least an altitude to clear the trees, but to no avail, nearly stalling." Subsequently, the biplane impacted the trees. The biplane sustained substantial damage to the wings and fuselage. The pilot reported that there were no preaccident mechanical failures or malfunctions with the biplane that would have precluded normal operation. The pilot added that the biplane is "not very stable once in a flying configuration, any air mass (gusts) change can disturb the balance and result in self-induced turns, climbs and descents. These movements have to be countered immediately because of the relative size (small) of control surfaces (rudder, ailerons). And corrections are slow, possibly resulting in loss of altitude. Pilots expect these upsets and become alert for them." The automated weather observation system on the accident airport reported, about the time of the accident, the wind was from 360° at 5 knots. The pilot was departing from runway 03. The calculated density altitude was 1,897 ft. ## Factual narrative The pilot of the experimental, amateur-built, biplane reported that, following a normal initial climb, about 100 ft. above the ground, the biplane started an un-commanded turn to the left, followed by a descent. He added that, it became apparent that the flight path was into the tree line, and he "attempted to climb to possibly maintain at least an altitude to clear the trees, but to no avail, nearly stalling." Subsequently, the biplane impacted the trees. The biplane sustained substantial damage to the wings and fuselage. The pilot reported that there were no preaccident mechanical failures or malfunctions with the biplane that would have precluded normal operation. The pilot added that, the biplane is "not very stable once in a flying configuration, any air mass (gusts) change can disturb the balance and result in self-induced turns, climbs and descents. These movements have to be countered immediately because of the relative size (small) of control surfaces (rudder, ailerons). And corrections are slow, possibly resulting in loss of altitude. Pilots expect these upsets and become alert for them." The automated weather observation system on the accident airport reported, about the time of the accident, the wind was 360° at 5 knots. The pilot was departing on runway 03. The calculated density altitude was 1,897 ft. ## Aircraft - Registration: [N8262](https://openairdocs.org/aircraft/N8262), registered now, S/N WC001, built 2013 (OpenAirDocs) - Reported make and model: CHARLES D WALKER WALKER CURTISS JN4D (NO SERIES) - Registry model: [Charles D Walker WALKER CURTISS JN4D](https://openairdocs.org/model/charles-d-walker-walker-curtiss-jn4d) (registry code 05632UK) (OpenAirDocs) - Registry engine: [GM ECO TEC 2.4L](https://openairdocs.org/engine/gm-eco-tec-2-4l) (registry code 30900, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: WC001 - Year built: 2013 - Airframe hours: 330 - Engines: 150 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, April 1, 2017 - Departed: BWG, Bowling Green, KY - Destination: BWG, Bowling Green, KY - Airport: BWG, Bowling Green-Warren County Rg, runway 03, 6,501 × 150 ft, asphalt - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 75; injuries: minor; flight instructor, airline transport; airplane ratings: single-engine sea, single-engine land, multi-engine land; medical: basicmed; last flight review February 17, 2017; seat: rear; restraint: 3-point; flight hours: 20,000 total, 60 in this make and model, 17,000 as pilot in command, 25 in the last 90 days, 15 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 360° at 5 knots - Visibility: 9 statute miles - Lowest ceiling: 5,000 ft broken - Temperature: 79 °F, dew point 73 °F - Altimeter: 30.00 inHg - Observed at: KBWG ## 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 20170812013359A](https://openairdocs.org/incident/20170812013359A), Aug 12, 2017: Charles D Walker WALKER CURTISS JN4D, Bowling Green, KY, Substantial damage. Aircraft took off on runway 3AT bwg initiated a left turn and could not recover, striking trees outside of airport perimeter fence and impacting ground… ## Other investigations on N8262 (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 ERA23LA231](https://openairdocs.org/ntsb/ERA23LA231), May 15, 2023: Charles D Walker Walker Curtiss JN4D (N8262), Greenville, KY, substantial damage. Probable cause: The separation of an electrical wire that powered the ignition module, rendering the ignition system inoperative, and resulting in the total loss of engine power. ## Docket (2 files) The files NTSB released with the investigation on October 23, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95820. 966 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 630 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457282&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Accident Photo (item 2, .PDF, 1 photo, 336 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457283&FileExtension=.PDF&FileName=Accident%20Photo-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.