# NTSB WPR26LA230: Stephen Aberle Chipper CH-2A, N618SA, Alva, OK, June 21, 2026 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 4 · Limited · Final report - Date: June 21, 2026, 09:30 local (14:30 UTC) - Place: Alva, OK · KAVK - Alva Regional Airport - Coordinates: 36.773577, -98.671166 - Nearby events: https://openairdocs.org/map.md?lat=36.7736&lon=-98.6712&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Defining event: [Taxi: Loss of visual reference](https://openairdocs.org/ntsb-events/402) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report September 17, 2026 - Report: Approved by Office Director - Investigation class: Class 4 - Basic report with no Prelim publish - NTSB office: Western Pacific Region - Parties: FAA - OKC FSDO - NTSB case key (mKey): 203234 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR26LA230 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/203234/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=203234 - Page: https://openairdocs.org/ntsb/WPR26LA230 ## Probable cause The pilot's decision to taxi the tailwheel-equipped airplane over uneven terrain while operating with limited forward visibility, which resulted in the left main landing gear entering a hole. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Terrain: rough terrain](https://openairdocs.org/ntsb-findings/03021015): Environmental issues › Physical environment · Awareness of condition (probable cause); cases with it: [Stephen Aberle CHIPPER CH-2A, 1 case](https://openairdocs.org/ntsb-findings/03021015/cases.md?model=05639F3), [All aircraft, 442 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md) - [Info processing/decision: identification/recognition](https://openairdocs.org/ntsb-findings/02041510): Personnel issues › Action/decision · Pilot; cases with it: [Stephen Aberle CHIPPER CH-2A, 1 case](https://openairdocs.org/ntsb-findings/02041510/cases.md?model=05639F3), [All aircraft, 559 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md) - [Attention/monitoring: monitoring environment](https://openairdocs.org/ntsb-findings/02021545): Personnel issues › Psychological · Pilot; cases with it: [Stephen Aberle CHIPPER CH-2A, 1 case](https://openairdocs.org/ntsb-findings/02021545/cases.md?model=05639F3), [All aircraft, 809 cases](https://openairdocs.org/ntsb-findings/02021545/cases.md) - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Stephen Aberle CHIPPER CH-2A, 1 case](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=05639F3), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Taxi: Loss of visual reference](https://openairdocs.org/ntsb-events/402) (defining event); cases with it: [Stephen Aberle CHIPPER CH-2A, 1 case](https://openairdocs.org/ntsb-events/402/sequence.md?model=05639F3), [All aircraft, 242 cases](https://openairdocs.org/ntsb-events/402/sequence.md) - [Taxi-from runway: Landing gear collapse](https://openairdocs.org/ntsb-events/094); cases with it: [Stephen Aberle CHIPPER CH-2A, 1 case](https://openairdocs.org/ntsb-events/094/sequence.md?model=05639F3), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis The pilot reported that he landed the tailwheel-equipped airplane in a grassy area between the paved runway and taxiway, which he stated is common practice at the airport. After touchdown, the airplane’s tailwheel settled to the surface, reducing the pilot’s forward visibility. The pilot continued straight ahead before initiating a left turn to a service road. Before reaching the service road, the left main landing gear entered a hole in the uneven terrain, resulting in substantial damage to the lower fuselage. The pilot's decision to continue taxiing with limited forward visibility over uneven terrain prevented him from detecting and avoiding the hole. The pilot reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. ## Aircraft - Registration: [N618SA](https://openairdocs.org/aircraft/N618SA), registered now, S/N 019, built 2024 (OpenAirDocs) - Reported make and model: STEPHEN ABERLE CHIPPER CH-2A - Registry model: [Stephen Aberle CHIPPER CH-2A](https://openairdocs.org/model/stephen-aberle-chipper-ch-2a) (registry code 05639F3) (OpenAirDocs) - Registry engine: [Aeromoment AM13 series](https://openairdocs.org/engine/aeromoment-am13-series) (registry code 00450, 4 cycle) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 019 - Year built: 2018 - Airframe hours: 16 - Engines: AEROMOMENTUM AM/13 100 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, April 29, 2026, 16.1 hours before - Departed: PVT, Kiowa, KS - Destination: Same as departure - Airport: AVK, Alva Regional, runway 18/36, 2,100 × 50 ft, grass/turf - Equipment: ADS-B, Electronic multifunction display, Electronic primary flight display, Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 25; injuries: none; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; last flight review February 4, 2026; seat: left; restraint: 4-point; flight hours: 235.1 total, 3.1 in this make and model, 169.8 as pilot in command, 9.7 in the last 90 days, 2.2 in the last 30 days, 0.4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 120° at 18 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 79 °F, dew point 64 °F - Altimeter: 29.74 inHg - Observed at: KAVK - METAR: METAR KAVK 211435Z AUTO 12018KT 10SM CLR 26/18 A2974 RMK A01 ## 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 20260621006469A](https://openairdocs.org/incident/20260621006469A), Jun 21, 2026: Stephen Aberle CHIPPER CH-2A, Alva, OK, Substantial damage. Upon landing on grass next to runway 18 at avk on June 21,2026 at approximately 0930 local. Pilot landed without issue and continued on runway heading to… ## Docket (2 files) The files NTSB released with the investigation on September 17, 2026, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=203234. 2.0 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 10 pages, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20871120&FileExtension=pdf&FileName=WPR26LA230_Accident_Redacted-Rel.pdf - Photos (item 2, PDF, 3 pages, 332 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20870953&FileExtension=pdf&FileName=WPR26LA230-Photos-Rel.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.