Lake LA-4-200 accident near Great Falls, Montana, December 28, 1983
On December 28, 1983 at about 5:10 am local time, a Lake LA-4-200, registered N39451, was substantially damaged in an accident near Great Falls, Montana (Great Falls airport). It was a personal flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The NTSB has not yet published a probable cause for this accident. Investigations usually take one to two years; this page updates when the final report is released.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- December 28, 1983 · about 5:10 am local time
- Place
- Great Falls, Montana · Great Falls · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Lake LA-4-200 · all LA-4-200s on the register
- Registration
- N39451 · no longer on the register · serial 541
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
THE ACFT WAS DAMAGED IN A FORCED LANDING ON A HIGHWAY AFTER THE ENGINE SEIZED. THE PLT SAID 'THE ENGINE MADE UNUSUAL SOUNDS OF AN ENGINE RUNNING BAD.' THEN IT LOST COMPRESSION AND SEIZED. HE MADE A FORCED LANDING ON A HIGHWAY AND DAMAGEDTHE HULL. EXAMINATION OF THE ACFT REVEALED A SITUATION WHERE THE MAIN OIL BREATHER FROZE PREVENTING OIL VAPOR PRESSURE FROM VENTING; CAUSING THE ENGINE SEALS TO FAIL AND THEREBY DEPLETNG THE OIL SUPPLY.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; single-engine sea; instructor: airplane single-engine; instrument: airplane
- Flight time: 1,865 hours in all; 8 in this make and model; 9 in the last 90 days; 1,650 as pilot in command
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 1,075 hours
- Last inspection: 100-hour inspection, June 15, 1983
- Maximum gross weight: 2,300 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming IO-360-A1B (piston); 0 hours total
The flight
- Departed from: MSO Missoula MT at 4:00 am
- Destination: MLS Miles City MT
- Flight plan: none
- Runway 0
Weather at the time
- Light: night, dark
- Wind: from 220° at 13 knots
- Visibility: 15 statute miles
- Sky: not recorded; scat at 25,000 ft
- Temperature: -9°F (-23°C), dew point 16°F (-9°C)
- Altimeter: 30.00 inHg
- Observation at 5:23 am from GTF
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.