Maule MX-7-235 accident near Boulder, Montana, May 23, 2008
On May 23, 2008 at about 8:28 pm local time, a Maule MX-7-235, registered N5657Y, was substantially damaged in an accident during enroute near Boulder, Montana. It was a personal flight under general aviation rules (Part 91). 1 person was killed and 1 person was seriously injured. The weather was instrument conditions (cloud, fog or low visibility).
The NTSB's probable cause their words, unchanged
The pilot's decision to continue flight at low altitude in instrument weather conditions and his failure to maintain clearance from a power line. Contributing to the accident were low cloud and visibility conditions.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 23, 2008 · about 8:28 pm local time
- Place
- Boulder, Montana · map
- Type
- Accident
- Injuries
- 1 person was killed and 1 person was seriously injured.
- Weather
- instrument conditions (cloud, fog or low visibility)
- Aircraft
- Maule MX-7-235 · all MX-7-235s on the register
- Registration
- N5657Y · no longer on the register · serial 10001C
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot received a weather briefing prior to departing on a cross-country personal flight. The weather briefer informed the pilot that a visual flight rules flight was not recommended along his intended route due to low ceilings, limited visibilities, and precipitation. While following an interstate highway at low altitude, the airplane collided with high-tension power lines that crossed the interstate, and came to rest in trees approximately 130 yards northwest of the lines. Fog, low clouds, snow, and rain were present in the area of the accident site both before and after the accident. The surviving passenger reported that no engine or airframe malfunctions were encountered during the flight.
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
- VFR encounter with IMC during enroute defining event
- Controlled flight into terrain or object (CFIT) during enroute
The NTSB's findings
- cause Environmental issues › Conditions/weather/phenomena › Ceiling/visibility/precip › Below VFR minima › Decision related to condition
- cause Personnel issues › Action/decision › Info processing/decision › Decision making/judgment › Pilot
- cause Environmental issues › Physical environment › Object/animal/substance › Wire › Response/compensation
- factor Environmental issues › Conditions/weather/phenomena › Ceiling/visibility/precip › Low ceiling › Not specified
- factor Environmental issues › Conditions/weather/phenomena › Ceiling/visibility/precip › Low visibility › Not specified
Pilot
- Certificate: airline transport pilot, flight instructor
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instrument: airplane
- Flight time: 20,000 hours in all; 1,000 in this make and model
- Last flight review: May 9, 2007
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: fatal
The aircraft
- Airframe total time: 1,409.2 hours
- Last inspection: annual inspection, April 9, 2008
- Seats: 5
- Landing gear: fixed
- Engine: Lycoming IO-540 SER (piston); 0 hours total
The flight
- Departed from: BTF Bountiful UT at 5:29 pm
- Destination: HLN Helena MT
- Flight plan: VFR
Weather at the time
- Light: daylight
- Wind: from 230° at 3 knots
- Visibility: 10 statute miles
- Sky: overcast at 2,000 ft
- Temperature: 46°F (8°C), dew point 39°F (4°C)
- Altimeter: 29.73 inHg
- Observation at 3:53 pm from BTM, 30 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 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.