# NTSB ANC23LA064: Piper PA-18, N4111Z, Skwentna, AK, August 22, 2023

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 4 · Limited · Final report
- Date: August 22, 2023, 12:00 local (20:00 UTC)
- Place: Skwentna, AK · gravel bar
- Coordinates: 61.877966, -151.34587
- Nearby events: https://openairdocs.org/map.md?lat=61.8780&lon=-151.3459&mi=10
- Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping)
- Defining event: [Taxi-from runway: Miscellaneous/other](https://openairdocs.org/ntsb-events/900)
- Highest injury: No injuries
- Injuries: 1 uninjured
- 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): 192953
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC23LA064
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/192953/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=192953
- Page: https://openairdocs.org/ntsb/ANC23LA064

## Probable cause

The pilot’s decision to taxi the airplane through tall grass without visual reference to the surface which obscured uneven terrain.

## 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-18, 12 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=7101802), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md)
- [Terrain: sloped/uneven terrain](https://openairdocs.org/ntsb-findings/03021017): Environmental issues › Physical environment · Effect on operation (probable cause); cases with it: [Piper PA-18, 1 case](https://openairdocs.org/ntsb-findings/03021017/cases.md?model=7101802), [All aircraft, 270 cases](https://openairdocs.org/ntsb-findings/03021017/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Taxi-from runway: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) (defining event); cases with it: [Piper PA-18, 5 cases](https://openairdocs.org/ntsb-events/900/sequence.md?model=7101802), [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md)

## Analysis

The pilot reported he landed on an unimproved strip, and then elected to reposition the airplane through an area of tall grass. During taxi, the main landing gear wheels hit a dip in the uneven terrain, and the airplane nosed over, sustaining substantial damage to the rudder and right wing. The pilot reported that there were no pre-accident mechanical failures or malfunctions with the airplane that would have precluded normal operation.

## Aircraft

- Registration: [N4111Z](https://openairdocs.org/aircraft/N4111Z), registered now, S/N 18-8153, built 1964 (OpenAirDocs)
- Reported make and model: PIPER PA-18
- Registry model: [Piper PA-18](https://openairdocs.org/model/piper-pa-18) (registry code 7101802) (OpenAirDocs)
- Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 18-8153
- Year built: 1964
- Airframe hours: 5105
- Engines: Lycoming O-320 A2B 160 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, June 4, 2023, 10 hours before
- Departed: PALH, Anchorage, AK
- Destination: Same as departure
- Equipment: Satellite tracking device

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 38; injuries: none; commercial, airline transport, private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 1; last flight review May 22, 2023; seat: front; flight hours: 7,976 total, 448 in this make and model, 4,796 as pilot in command, 107 in the last 90 days, 62 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 61 °F, dew point 52 °F
- Altimeter: 30.06 inHg
- Observed at: PATK, 44 nm away
- METAR: PATK 221953Z 00000KT 10SM CLR 16/11 A3006 RMK AO2 SLP181 T01560106


## 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 20230822014509A](https://openairdocs.org/incident/20230822014509A), Aug 22, 2023: Piper PA-18, Skwentna, AK, Substantial damage. Pilot stated he was flying the single engine airplane into a private airstrip 15 NM southwest of skwenta to check on a cabin property for a friend. While taxi…

## Other investigations on N4111Z (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 ANC07CA039](https://openairdocs.org/ntsb/ANC07CA039), May 26, 2007: Piper PA-18 (N4111Z), Fairbanks, AK, substantial damage. Probable cause: The pilot's failure to maintain altitude/clearance while maneuvering, which resulted in a collision with trees. A factor contributing to the accident was dusk lighting conditions.

## Docket (2 files)

The files NTSB released with the investigation on April 4, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=192953. 10.9 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 10.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16200878&FileExtension=pdf&FileName=NTSB%20Form%206120_Redacted-Rel.pdf
- Photos (item 2, PDF, 3 pages, 346 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16187185&FileExtension=pdf&FileName=ANC23LA064%20Photos-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.

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