Amateur-built MONI accident near Byron, California, August 18, 1985
On August 18, 1985 at about 6:30 pm local time, a amateur-built MONI, registered N97MS, was destroyed in an accident near Byron, California (Concord airport). It was an other work-use 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).
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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 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 18, 1985 · about 6:30 pm local time
- Place
- Byron, California · Concord · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built MONI
- Registration
- N97MS · registry record
- Damage
- Destroyed
- Flight
- Other work-use flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
WHILE ON THE INITIAL TEST FLT, THE AMATUER-BUILT R. M. STONE MONI ACFT CRASHED NEAR BYRON, CA. THE PLT REPORTED THAT DURING THE FLIGHT THE ACFT BEGAN TO 'FLUTTER', FOLLOWED BY SEPARATION OF THE CANOPY. SHORTLY THEREAFTER THE ACFT ENTERED INTO AN UNCONTROLLABLE SPIN. THE PLT EXITED THE ACFTAND PARACHUTED SAFELY. THE ACFT WAS NOT RECOVERED.
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: commercial pilot
- Ratings: single-engine land; instrument: airplane; rotorcraft: helicopter
- Medical certificate: Unknown
- Seat: unk
The aircraft
- Last inspection: inspection type not recorded
- Landing gear: fixed
- Engine: Unknown UNKNOWN (piston); 0 hours total
The flight
- Departed from: LVK Livermore CA at 4:30 pm
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 330° at 8 knots
- Visibility: 20 statute miles
- Sky: clear
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
- Altimeter: 30.00 inHg
- Observation at 6:45 pm from LVK, 20 miles away
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.
Other NTSB records under N97MS the same tail number, which may have belonged to a different aircraft at the time
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number LAX85LA353.