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NTSB investigations: Amateur-built UNKNOWN ENG, MT

25 cases on aircraft whose registry engine model is Amateur-built UNKNOWN ENG. Aircraft are matched to the registry by N-number and event date, checked against the reported serial number, make and model, so older matches can be wrong.

Defining event

Finding

Phase of flight

Aircraft model

Cases per year

19662026

Where

Latest cases

Query with SQL

SELECT c."ntsbNumber", c."eventDate", c."eventType", c."eventCity", c."eventStateOrRegion", a.n_number, a."aircraftMake", a."aircraftModel", c."highestInjuryLevel", c."totalFatal", c."completionStatus", c.report_url FROM 'https://openairdocs.org/data/latest/ntsb_case_detail.parquet' c LEFT JOIN 'https://openairdocs.org/data/latest/ntsb_aircrafts.parquet' a ON a.case_mkey = c."mKey" AND a.position = 1 WHERE c."eventStateOrRegion" = 'MT' AND c."eventCountry" = 'USA' AND c."mKey" IN (SELECT x.case_mkey FROM 'https://openairdocs.org/data/latest/ntsb_aircrafts.parquet' x WHERE x.engine_model_code IN ('99999')) ORDER BY c."eventDate" DESC, c."ntsbNumber" DESC

duckdb -csv -c "SELECT c.\"ntsbNumber\", c.\"eventDate\", c.\"eventType\", c.\"eventCity\", c.\"eventStateOrRegion\", a.n_number, a.\"aircraftMake\", a.\"aircraftModel\", c.\"highestInjuryLevel\", c.\"totalFatal\", c.\"completionStatus\", c.report_url
  FROM 'https://openairdocs.org/data/latest/ntsb_case_detail.parquet' c LEFT JOIN 'https://openairdocs.org/data/latest/ntsb_aircrafts.parquet' a ON a.case_mkey = c.\"mKey\" AND a.position = 1
  WHERE c.\"eventStateOrRegion\" = 'MT' AND c.\"eventCountry\" = 'USA'
    AND c.\"mKey\" IN (SELECT x.case_mkey FROM 'https://openairdocs.org/data/latest/ntsb_aircrafts.parquet' x WHERE x.engine_model_code IN ('99999'))
  ORDER BY c.\"eventDate\" DESC, c.\"ntsbNumber\" DESC"

Prints the whole list as CSV. It reads the release’s Parquet files over HTTPS, so there’s nothing to download first. Install DuckDB to run it.

SELECT c."ntsbNumber", c."eventDate", c."eventType", c."eventCity", c."eventStateOrRegion", a.n_number, a."aircraftMake", a."aircraftModel", c."highestInjuryLevel", c."totalFatal", c."completionStatus", c.report_url
FROM 'https://openairdocs.org/data/latest/ntsb_case_detail.parquet' c LEFT JOIN 'https://openairdocs.org/data/latest/ntsb_aircrafts.parquet' a ON a.case_mkey = c."mKey" AND a.position = 1
WHERE c."eventStateOrRegion" = 'MT' AND c."eventCountry" = 'USA'
  AND c."mKey" IN (SELECT x.case_mkey FROM 'https://openairdocs.org/data/latest/ntsb_aircrafts.parquet' x WHERE x.engine_model_code IN ('99999'))
ORDER BY c."eventDate" DESC, c."ntsbNumber" DESC

Run it at the DuckDB prompt, or in any tool that reads Parquet over HTTPS. More ways to query the release are on Use the data.

NTSB WPR25LA271Accident · Minor injuriesClass 4 · LimitedFinal reportNaval Aircraft Factory N3N-3 · Red Lodge, MTThe pilot’s failure to maintain clearance from obstacles during an aborted landing. Contributing to the accident was the high density altitude weather condition.Aug 31, 2025 · N45254 · Substantial damage NTSB WPR23LA354Accident · No injuriesClass 4 · LimitedFinal reportKerr John Hatz Classic · Ennis, MTThe pilot’s failure to maintain directional control during the landing roll which resulted in a ground-loop.Apr 29, 2023 · N687HZ · Substantial damage NTSB WPR21LA219Accident · Serious injuriesClass 3 · LimitedFinal reportStoddard Hamilton Glasair II · Darby, MTThe pilot’s impact with terrain during a go-around following an attempted precautionary landing due to a low oil pressure indication. The reason for the low oil pressure indication could not be determined based on the available information.May 29, 2021 · N8176J · Substantial damage NTSB GAA19CA475Accident · Serious injuriesData collectionFinal reportAvid Avid Mark IV · Thompson Falls, MTThe student pilot's failure to go-around after a hard, bounced landing and the flight instructor's delayed remedial action, which resulted in a collision with trees at the departure end of the runway.Jul 30, 2019 · N4829W · Substantial damage NTSB GAA18CA437Accident · No injuriesData collectionFinal reportCessna 180 · Bozeman, MTThe pilot's failure to maintain directional control during landing.Jul 19, 2018 · N3224D · Substantial damage NTSB WPR16FA012Accident · 1 fatalField investigationFinal reportBucker Jungmeister BU 133 · Missoula, MTThe pilot’s failure to maintain adequate airspeed and his exceedance of the airplane’s critical angle of attack while executing a return to the runway after takeoff, which resulted in an aerodynamic stall/spin. Contributing to the accident was the pilot’s…Oct 14, 2015 · N1940J · Destroyed NTSB WPR11CA281Accident · No injuriesData collectionFinal reportPiper PA-36-285 · Havre, MTThe pilot's failure to maintain directional control during takeoff.Jun 23, 2011 · N57736 · Substantial damage NTSB SEA08CA010Accident · No injuriesData collectionFinal reportWelch RV-9 · Bigfork, MTFuel starvation while on downwind for landing. The pilot's inadequate in-flight fuel management planning was a factor.Oct 14, 2007 · N475TW · Substantial damage NTSB SEA06LA167Accident · Minor injuriesLimited investigationFinal reportKinnson Lancair IV-P Turbine · Helena, MTThe total loss of engine power as a result of turbine over temperature due to the pilot's failure to follow proper procedures for engine operation. A contributing factor was the lack of suitable terrain for the ensuing forced landing.Aug 22, 2006 · N514PT · Substantial damage NTSB SEA06CA080Accident · No injuriesData collectionFinal reportPitrolo GL-25 · Worden, MTThe loss of engine power due to failure of both electronic ignition systems. A contributing factor was the lack of suitable terrain for the forced landing.Apr 21, 2006 · N27EP · Substantial damage NTSB SEA06LA074Accident · No injuriesLimited investigationFinal reportCentral Copters Lancair IV-P · Belgrade, MTThe total loss of drive power to the aircraft's propeller while on a visual final approach, due to the decoupling of the quill shaft between the reduction gearbox and the engine power section. Factors include a dark night, no suitable terrain on which to…Apr 15, 2006 · N671 · Destroyed NTSB SEA05LA189Accident · No injuriesLimited investigationFinal reportBallhagen/Shyrock Q-2 · Kalispell, MTThe pilot/owner's improper setting of the engine's valve clearance, leading to the failure of the exhaust valves to fully close and a total loss of power while on a VFR downwind, and the pilot/owner's failure to maintain sufficient airspeed as he tried to…Sep 2, 2005 · N12QJ · Substantial damage NTSB SEA03LA007Accident · 1 fatalLimited investigationFinal reportRiddell IV-P · Bozeman, MTThe loss of power for undetermined reason(s) and the pilot's failure to maintain the aircraft's flying speed above the power off stall speed in the landing configuration.Nov 5, 2002 · N41RJ · Destroyed NTSB SEA02LA130Accident · No injuriesLimited investigationFinal reportThurmond Moni · Laurel, MTUndertorqued mounting bolts which resulted in fatigue to the wooden propeller blade and subsequent in flight separation of one of the blades while in cruise flight. An improper installation of the propeller assembly and soft terrain encountered during the…Jul 12, 2002 · N9104S · Substantial damage NTSB SEA00LA144Accident · Serious injuriesLimited investigationFinal reportEiriavion PIK 20E · Hamilton, MTThe pilot's entering an inadvertent stall condition during a high angle of bank turn (maneuvering), and the lack of adequate altitude in which to successfully recover before ground impact.Jul 26, 2000 · N27RT · Destroyed NTSB SEA99LA081Accident · 1 fatalLimited investigationFinal reportD. Wayne Smith Wayncraft 14 · Libby, MTCollision with terrain for undetermined reasons.Jun 6, 1999 · N58WS · Substantial damage NTSB SEA99LA061Accident · No injuriesLimited investigationFinal reportEugene Hughes Lancair IV · Butte, MTThe pilot's improper flare.May 8, 1999 · N124GH · Substantial damage NTSB SEA98LA016Accident · No injuriesLimited investigationFinal reportShort Brothers SD3-60 · Billings, MTThe co-pilot's failure to maintain the proper descent rate on final approach, the pilot-in-command's delayed remedial action, and overload of the left main landing gear assembly. Factors contributing were snow, crosswind conditions and deteriorating…Nov 25, 1997 · N691A · Substantial damage NTSB SEA94LA244Accident · No injuriesLimited investigationFinal reportI.C.A. Brasov IS-28B2 · Bozeman, MTThe student pilot's improper compensation for wind. The crosswind was a factor.Sep 10, 1994 · N28KG · Substantial damage NTSB SEA91LA031Accident · No injuriesLimited investigationFinal reportBeech 3NM · Bozeman, MTThe failure of the right engine master rod.Dec 9, 1990 · N9159B · Substantial damage NTSB SEA90LA150Accident · No injuriesLimited investigationFinal reportGlasflugel H 301 Libelle · Thompson Falls, MTA disabled aircraft blocking the active runway.Jul 29, 1990 · N4166A · Substantial damage NTSB DEN85FA131Accident · 1 fatalField investigationFinal reportConsolidated-Vultee PBY-5A · Lewistown, MTDuring taxi to takeoff the brakes failed. The plt attempted to groundloop the acft. The acft rolled down hill and collided with a gully. The plt was fatally injured. During preflight the co-plt inadvertently added hydraulic fluid in the alcohol tank. The…May 9, 1985 · N84857 · Substantial damage NTSB DEN83LTI01Accident · No injuriesFinal reportScorpion 133 · Manhattan, MTBattery failed because it had not been charged. No on board charging provision. Electric pump could not operate without electricity. No fuel to engine. During an autorotative landing, the tail rotor was damaged. With no tail rotor control, the helicopter slid…Oct 3, 1982 · N133RW · Substantial damage NTSB SEA79FTI15Accident · No injuriesClosedScorpion II · Belgrade, MTMay 21, 1979 · N133RW · Substantial damage NTSB SEA67A0027Accident · 2 fatalClosedBell 47G3B1 · W.Yellowston, MTSep 21, 1966 · N1169W · Destroyed