# NTSB GAA19CA132: Piper PA 18A, N8170C, McGrath, AK, January 28, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: January 27, 2019, 15:00 local (Jan 28, 2019, 00:00 UTC) - Place: McGrath, AK - Coordinates: 62.786109, -154.753616 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=62.7861&lon=-154.7536&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing: Landing gear collapse](https://openairdocs.org/ntsb-events/094) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report September 26, 2019 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA - NTSB case key (mKey): 98962 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA19CA132 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/98962/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=98962 - Page: https://openairdocs.org/ntsb/GAA19CA132 ## Probable cause The pilot's selection of unsuitable terrain for landing, which resulted in the landing gear collapsing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Runway/land/takeoff/taxi surface: snow/slush/ice covered surface](https://openairdocs.org/ntsb-findings/03023015): Environmental issues › Physical environment · Decision related to condition (probable cause); cases with it: [Piper PA-18A, 1 case](https://openairdocs.org/ntsb-findings/03023015/cases.md?model=7101804), [All aircraft, 219 cases](https://openairdocs.org/ntsb-findings/03023015/cases.md) - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Piper PA-18A, 4 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=7101804), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) - [Runway/land/takeoff/taxi surface: snow/slush/ice covered surface](https://openairdocs.org/ntsb-findings/03023015): Environmental issues › Physical environment · Effect on equipment; cases with it: [Piper PA-18A, 1 case](https://openairdocs.org/ntsb-findings/03023015/cases.md?model=7101804), [All aircraft, 219 cases](https://openairdocs.org/ntsb-findings/03023015/cases.md) - [Attention/monitoring: monitoring environment](https://openairdocs.org/ntsb-findings/02021545): Personnel issues › Psychological · Pilot; cases with it: [Piper PA-18A, 2 cases](https://openairdocs.org/ntsb-findings/02021545/cases.md?model=7101804), [All aircraft, 809 cases](https://openairdocs.org/ntsb-findings/02021545/cases.md) - [Object/animal/substance](https://openairdocs.org/ntsb-findings/03022000): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Piper PA-18A, 1 case](https://openairdocs.org/ntsb-findings/03022000/cases.md?model=7101804), [All aircraft, 224 cases](https://openairdocs.org/ntsb-findings/03022000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Piper PA-18A, 2 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=7101804), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Piper PA-18A, 10 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7101804), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot of the ski-equipped airplane reported that, while landing off-airport on a snow-covered field, he side-loaded the landing gear on the left side against a large "tussock" hidden by the snow. The left landing gear folded under the airplane, which caused the left wingtip to drop into the snow and impact a snow-covered tussock. The airplane sustained substantial damage to the left wing. The pilot reported that there were no preimpact mechanical failures or malfunctions with the airplane that would have precluded normal operation. ## Factual narrative The pilot of the ski-equipped airplane reported that, while landing off-airport on a snow-covered field, he side loaded the landing gear on the left side against a large "tussock" hidden by the snow. The left landing gear folded under the airplane, causing the left wingtip to drop into the snow and impact a snow-covered tussock. The airplane sustained substantial damage to the left wing. The pilot reported that there were no preimpact mechanical failures or malfunctions with the airplane that would have precluded normal operation. ## Aircraft - Registration: [N8170C](https://openairdocs.org/aircraft/N8170C), registered now, S/N 18-3626, built 1954 (OpenAirDocs) - Reported make and model: Piper PA 18A (135) - Registry model: [Piper PA-18A](https://openairdocs.org/model/piper-pa-18a) (registry code 7101804) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18-3626 - Year built: 1954 - Airframe hours: 415 - Engines: Lycoming O-320 A2B 150 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, November 7, 2018 - Departed: MCG, Mcgrath, AK - Destination: MCG, Mcgrath, AK - Flight plan: Company VFR - Equipment: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 44; injuries: none; commercial; airplane ratings: single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review January 16, 2018; seat: front; restraint: 3-point; flight hours: 8,800 total, 7,600 in this make and model, 8,780 as pilot in command, 66 in the last 90 days, 32 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 130° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: 11,000 ft overcast - Temperature: 37 °F, dew point 27 °F - Altimeter: 30.14 inHg - Observed at: PAMC, 26 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 20190127005779A](https://openairdocs.org/incident/20190127005779A), Jan 27, 2019: Piper PA-18A, Mcgrath, AK, Substantial damage. On Sunday January 27th PIC was operating N8170C, a Piper PA-18 on straight skis east of Mcgrath on my trapline. On about the ninth off airport landing of the… ## Docket (2 files) The files NTSB released with the investigation on March 14, 2019, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=98962. 3.5 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40471055&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Accident Photo (item 2, .PDF, 1 photo, 98 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40471056&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.