# NTSB CEN23LA287: Aerofab LA-4, N993PT, Big Prairie, MI, July 8, 2023

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 4 · Limited · Final report
- Date: July 8, 2023, 09:10 local (13:10 UTC)
- Place: Big Prairie, MI
- Coordinates: 43.511549, -85.617011 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=43.5115&lon=-85.6170&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Defining event: [Landing: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 4 - Basic report with no Prelim publish
- NTSB office: Central Region
- Parties: Federal Aviation Administration
- NTSB case key (mKey): 192569
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN23LA287
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/192569/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=192569
- Page: https://openairdocs.org/ntsb/CEN23LA287

## Probable cause

The airplane’s collision with a submerged log during a water landing.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Object/animal/substance: hidden/submerged object](https://openairdocs.org/ntsb-findings/03022052): Environmental issues › Physical environment · Effect on equipment (probable cause); cases with it: [Aerofab LA-4, 1 case](https://openairdocs.org/ntsb-findings/03022052/cases.md?model=5110312), [All aircraft, 36 cases](https://openairdocs.org/ntsb-findings/03022052/cases.md)
- [Object/animal/substance: hidden/submerged object](https://openairdocs.org/ntsb-findings/03022052): Environmental issues › Physical environment · Awareness of condition (probable cause); cases with it: [Aerofab LA-4, 1 case](https://openairdocs.org/ntsb-findings/03022052/cases.md?model=5110312), [All aircraft, 36 cases](https://openairdocs.org/ntsb-findings/03022052/cases.md)

## Sequence of events

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

- [Landing: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490) (defining event); cases with it: [Aerofab LA-4, 1 case](https://openairdocs.org/ntsb-events/490/sequence.md?model=5110312), [All aircraft, 1,309 cases](https://openairdocs.org/ntsb-events/490/sequence.md)

## Analysis

The flight instructor and pilot receiving instruction were completing water landings in the amphibious airplane. They had already completed several landings on the same pond without incident. During the accident landing, upon touchdown the airplane impacted a submerged log, which punctured a large hole in the hull. The pilots egressed without further incident and the airplane sank. The pilot reported no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation.

## Aircraft

- Registration: [N993PT](https://openairdocs.org/deregistered/N993PT-2024-10-22), registration cancelled 2024-10-22, S/N 341, built 1966 (OpenAirDocs)
- Reported make and model: AEROFAB LA-4 (180)
- Registry model: [Aerofab LA-4](https://openairdocs.org/model/aerofab-la-4) (registry code 5110312) (OpenAirDocs)
- Registry engine: [Lycoming O-360-A1A](https://openairdocs.org/engine/lycoming-o-360-a1a) (registry code 41594, 4 cycle) (OpenAirDocs)
- Category: Airplane
- Serial number: 341
- Year built: 1966
- Airframe hours: 2533
- Engines: Lycoming O-360-A1A 180 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, October 19, 2022
- Departed: 3GM, Grand Haven, MI
- Equipment: Stall warning system, Electronic flight bag or handheld device, ADS-B

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 55; injuries: none; private; airplane ratings: single-engine land, single-engine sea; medical: basicmed, without waivers/limitations; last flight review February 1, 2023; seat: left; restraint: 3-point; flight hours: 1,372 total, 121 in this make and model, 1,266 as pilot in command, 57 in the last 90 days, 24 in the last 30 days, 6 in the last 24 hours
- Flight instructor; age 56; injuries: none; airline transport, flight instructor; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane; medical: class 1, with waivers/limitations; seat: right; restraint: 3-point

## Weather

- Conditions: Visual (VMC), Day
- Wind: 180° at 4 knots
- Visibility: 10 statute miles
- Lowest ceiling: 4,100 ft broken
- Temperature: 63 °F, dew point 57 °F
- Altimeter: 29.89 inHg
- Observed at: KRQB, 13 nm away
- METAR: KRQB 081255Z AUTO 18004KT 10SM BKN041 OVC049 17/14 A2989 RMK AO2 T01660137

## 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 20230708008699A](https://openairdocs.org/incident/20230708008699A), Jul 8, 2023: Aerofab LA-4, White Cloud, MI, Substantial damage. On July 8, 2023 at 0940 local time, a 1966 Aerofab (lake) LA-4 amphibian aircraft, [privacy data omitted], registered to and operated by a private pilot…

## Docket (2 files)

The files NTSB released with the investigation on September 28, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=192569. 6.4 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 4.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15923896&FileExtension=pdf&FileName=6120%20-%20pilot%20(signed)_Redacted-Rel.pdf
- Photos (item 2, PDF, 3 pages, 3 photos, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15924357&FileExtension=pdf&FileName=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.

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