# NTSB ANC19TA055: Stinson 108, N6533M, Tyonek, AK, September 26, 2019 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Class 4 · Final report - Date: September 25, 2019, 19:00 local (Sep 26, 2019, 03:00 UTC) - Place: Tyonek, AK - Coordinates: 60.978889, -151.89222 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=60.9789&lon=-151.8922&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Loss of lift](https://openairdocs.org/ntsb-events/500) - Highest injury: Serious injuries - Injuries: 1 serious, 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 4 - Basic report with no Prelim publish - NTSB office: Alaska Regional Office - Parties: FAA FSDO - NTSB case key (mKey): 100339 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC19TA055 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/100339/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=100339 - Page: https://openairdocs.org/ntsb/ANC19TA055 ## Probable cause The pilot’s exceedance of the airplane’s critical angle of attack during a short field takeoff, which resulted in an aerodynamic stall and loss of control. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Wind: sudden wind shift](https://openairdocs.org/ntsb-findings/03034010): Environmental issues › Conditions/weather/phenomena · Effect on operation (probable cause); cases with it: [Stinson 108-3, 1 case](https://openairdocs.org/ntsb-findings/03034010/cases.md?model=9230408), [All aircraft, 114 cases](https://openairdocs.org/ntsb-findings/03034010/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Stinson 108-3, 9 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=9230408), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: angle of attack](https://openairdocs.org/ntsb-findings/01062042): Aircraft › Aircraft oper/perf/capability · Capability exceeded (probable cause); cases with it: [Stinson 108-3, 3 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md?model=9230408), [All aircraft, 990 cases](https://openairdocs.org/ntsb-findings/01062042/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 lift](https://openairdocs.org/ntsb-events/500) (defining event); cases with it: [Stinson 108-3, 2 cases](https://openairdocs.org/ntsb-events/500/sequence.md?model=9230408), [All aircraft, 252 cases](https://openairdocs.org/ntsb-events/500/sequence.md) - [Initial climb: Loss of control in flight](https://openairdocs.org/ntsb-events/240); cases with it: [Stinson 108-3, 5 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=9230408), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Stinson 108-3, 15 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=9230408), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that during a short field takeoff from a small unimproved airstrip, as the airplane climbed through tree top altitude, the indicated airspeed decreased by 20-30 knots and the left wing dropped rapidly. The airplane descended and impacted trees beyond the airstrip. The wings and fuselage sustained substantial damage and the pilot sustained serious injuries. The passenger sustained minor injuries. The pilot stated that there were no mechanical malfunctions or failures that would have precluded normal operation and that the wind likely diminished during a critical phase of the climb out, and due to the slow airspeed, the left wing stalled resulting in an uncontrolled left roll. ## Aircraft - Registration: [N6533M](https://openairdocs.org/aircraft/N6533M), registered now, S/N 108-4533 (OpenAirDocs) - Reported make and model: Stinson 108 (3) - Registry model: [Stinson 108-3](https://openairdocs.org/model/stinson-108-3) (registry code 9230408) (OpenAirDocs) - Registry engine: [Franklin 6A4165 series](https://openairdocs.org/engine/franklin-6a4165-series) (registry code 27025, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 108-4533 - Engines: Franklin 6A4165 SERIES 165 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Departed: Tyonek, AK - Destination: SXQ, Soldotna, AK ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 65; injuries: serious; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; seat: front; flight hours: 800 total, 800 in this make and model, 800 as pilot in command, 30 in the last 90 days, 6 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 250° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 48 °F, dew point 32 °F - Altimeter: 29.91 inHg - Observed at: PAEN, 31 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 20190925015729A](https://openairdocs.org/incident/20190925015729A), Sep 25, 2019: Stinson 108-3, Tyonek, AK, Substantial damage. Pilot in command/owner stated that he is familiar with the landing and takeoff area with more than six trips in and out of the unimproved surface area over the… ## Docket (3 files) The files NTSB released with the investigation on August 20, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=100339. 971 KB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 10 pages, 585 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11800622&FileExtension=pdf&FileName=6120%20master_Redacted-Rel.pdf - Record of conversation (pilot) (item 2, PDF, 1 page, 151 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11801115&FileExtension=pdf&FileName=ROC%20Pilot%20MBeckwith-Rel.pdf - Photograph (item 3, PDF, 1 page, 236 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11801232&FileExtension=pdf&FileName=Photo-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.