Amateur-built BU 133 accident near Missoula, Montana, October 14, 2015
On October 14, 2015 at about 9:10 pm local time, a 1940 amateur-built BU 133, registered N1940J, was destroyed in an accident during initial climb near Missoula, Montana (Missoula Intl airport). It was a personal flight under general aviation rules (Part 91). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The 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 decision to take off with a known mechanical problem.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- October 14, 2015 · about 9:10 pm local time
- Place
- Missoula, Montana · Missoula Intl · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built BU 133 C, built 1940
- Registration
- N1940J · no longer on the register · serial 22
- Damage
- Destroyed
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The airline transport pilot purchased the airplane the day before the accident and was flying it across the country to his home airport. After landing at the accident airport, the pilot spoke on the telephone to a mechanic familiar with the airplane. The pilot reported to the mechanic that, after both of his earlier refueling stops, during the take climb, fuel had entered the cockpit, but after flying for a while, it stopped. The pilot stated that someone was helping him inspect the fuel system, but they were not able to find anything wrong. The mechanic stated that it sounded like a fuel venting problem and recommended that the pilot not fly the airplane until the issue was resolved. The pilot told the mechanic that he needed to get the airplane home and said that he was going to depart with all electrical power off. On the initial takeoff climb, witnesses saw the airplane enter a steep right turn; this was consistent with the pilot attempting to return to the runway. After turning about 180°, the airplane stalled, entered a spin, and descended to ground impact. Upon impact, a fire erupted, which consumed most of the airplane. Although the pilot had told the mechanic that he had someone help him inspect the fuel system, no one was identified at the accident airport who reported helping the pilot inspect the fuel system or seeing the pilot or anyone else perform such an inspection. Therefore, it is likely that the pilot experienced the same fuel leakage problem on the accident takeoff that he had experienced after his previous refueling stops. Extensive postcrash fire damage to the fuel system prevented determination of the source of the fuel leak. The fuel selector was found in the "off" position. Because the pilot choses to take off with no electrical power, he was unable to communicate the reason for his turn to tower controllers. It is likely that the pilot was distracted by fuel entering the cockpit and failed to maintain adequate airspeed as he was returning to the airport to rectify the problem, which resulted in the airplane exceeding its critical angle of attack and an aerodynamic stall/spin. Toxicology testing identified 10% carbon monoxide in the pilot's specimens. This was likely due to the postcrash fire.
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
What happened, in order
- Loss of control in flight during initial climb defining event
- Collision with terrain or object (not controlled flight into terrain) during initial climb
- Aerodynamic stall/spin during initial climb
The NTSB's findings
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Airspeed › Not attained/maintained
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Angle of attack › Capability exceeded
- factor Personnel issues › Action/decision › Info processing/decision › Decision making/judgment › Pilot
- cause Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
Pilot
- Certificate: airline transport pilot, commercial pilot, private
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instrument: airplane; rotorcraft: glider
- Flight time: 11,200 hours in all
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: sngl
- Injury: fatal
The aircraft
- Airframe total time: 2,038.9 hours
- Last inspection: annual inspection, June 12, 2015
- Seats: 1
- Landing gear: fixed
- Engine: Warner Aircraft Engines 1650 (piston); 0 hours total
- Fire on the ground
The flight
- Departed from: MSO Missoula MT at 9:10 pm
- Flight plan: none
- Runway 25, 4,612 ft by 75 ft
Weather at the time
- Light: daylight
- Wind: from 320° at 7 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 68°F (20°C), dew point 37°F (3°C)
- Altimeter: 30.18 inHg
- Observation at 8:53 pm from KMSO
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight 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.