# NTSB ANC10CA016: Piper PA-17, N4568H, Skwentna, AK, January 31, 2010 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Data collection · Final report - Date: January 31, 2010, 16:00 local (20:00 UTC) - Place: Skwentna, AK - Coordinates: 61.563888, -151.557785 - Nearby events: https://openairdocs.org/map.md?lat=61.5639&lon=-151.5578&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach-VFR pattern final: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report May 28, 2010 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA, Anchorage FSDO - NTSB case key (mKey): 75327 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC10CA016 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/75327/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=75327 - Page: https://openairdocs.org/ntsb/ANC10CA016 ## Probable cause The pilot's decision to make a low-altitude approach to land over trees in gusting winds, which resulted in an in-flight collision with a tree and a loss of control. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Piper PA-17, 2 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=7101702), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) - [Wind: sudden wind shift](https://openairdocs.org/ntsb-findings/03034010): Environmental issues › Conditions/weather/phenomena · Effect on operation; cases with it: [Piper PA-17, 1 case](https://openairdocs.org/ntsb-findings/03034010/cases.md?model=7101702), [All aircraft, 114 cases](https://openairdocs.org/ntsb-findings/03034010/cases.md) - [Performance/control parameters: descent/approach/glide path](https://openairdocs.org/ntsb-findings/01062040): Aircraft › Aircraft oper/perf/capability · Not attained/maintained; cases with it: [Piper PA-17, 1 case](https://openairdocs.org/ntsb-findings/01062040/cases.md?model=7101702), [All aircraft, 809 cases](https://openairdocs.org/ntsb-findings/01062040/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach-VFR pattern final: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490) (defining event); cases with it: [Piper PA-17, 1 case](https://openairdocs.org/ntsb-events/490/sequence.md?model=7101702), [All aircraft, 1,309 cases](https://openairdocs.org/ntsb-events/490/sequence.md) - [Approach-VFR pattern final: Loss of control in flight](https://openairdocs.org/ntsb-events/240); cases with it: [Piper PA-17, 1 case](https://openairdocs.org/ntsb-events/240/sequence.md?model=7101702), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) ## Analysis The private pilot reported that he was on a personal flight and was attempting to land on a frozen lake. While on final approach to land, he said the airplane encountered a wind gust and that the left wing struck the top of a tree. The airplane descended and collided with terrain short of the intended landing site. The pilot stated that there were no preaccident mechanical problems with the airplane. ## Factual narrative The private pilot reported that he was on a personal flight and was attempting to land on a frozen lake. While on final approach to land, he said the airplane encountered a wind gust and that the left wing struck the top of a tree. The airplane descended and collided with terrain short of the intended landing site. The pilot stated that there were no preaccident mechanical problems with the airplane. ## Aircraft - Registration: [N4568H](https://openairdocs.org/deregistered/N4568H-2015-05-15), registration cancelled 2015-05-15, S/N 15-342, built 1948 (OpenAirDocs) - Reported make and model: PIPER PA-17 - Registry model: [Piper PA-17](https://openairdocs.org/model/piper-pa-17) (registry code 7101702) (OpenAirDocs) - Registry engine: [Continental C85 series](https://openairdocs.org/engine/continental-c85-series) (registry code 17008, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 15-342 - Engines: CONT MOTOR C90 90 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Ben Knapp - Registered owner: Knapp Alan L - Airworthiness certificate: Standard, Normal - Departed: na, Skwentna, AK - Destination: na, Skwentna, AK - Flight plan: Unknown - Airport: na, na, runway 36, ice ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 21; injuries: minor; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; seat: left; flight hours: 471 total, 31 in this make and model ## Weather - Conditions: Visual (VMC), Day ## Docket (1 files) The files NTSB released with the investigation on March 8, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=75327. 1.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326674&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.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.