Claxton S-12 accident near Oconomowoc, Wisconsin, September 12, 2004
On September 12, 2004 at about 6:20 pm local time, a Claxton S-12, registered UNREG, was destroyed in an accident near Oconomowoc, Wisconsin. 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 loss of engine power due to the seizure of the pistons and the pilot's failure to maintain airspeed which resulted in an inadvertent stall. The previous damage to the pistons due to earlier seizure occurrences was a factor.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 12, 2004 · about 6:20 pm local time
- Place
- Oconomowoc, Wisconsin · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Claxton S-12
- Registration
- UNREG · no longer on the register · serial 0991124
- Damage
- Destroyed
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The un-registered airplane was destroyed when it impacted the ground following an engine failure after takeoff. The non-certificated pilot was fatally injured. A witness reported seeing the airplane and hearing the engine "quit". The airplane then made a series of gliding turns before it impacted into a marsh. The witness did not see the impact. Examination of the airplane showed no anomalies with respect to the airframe or control system. The engine's pistons exhibited scuffing and scoring indicative of a seizure. The marks on the piston contained carbon deposits indicating that the engine had experienced a seizure prior to the accident flight that had not been repaired.
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
- Medical certificate: None
- Seat: left
- Injury: fatal
The aircraft
- Last inspection: inspection type not recorded
- Maximum gross weight: 975 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotax 582 (piston); 0 hours total
The flight
- Departed from: PVT Oconomowoc WI
- Destination: C89 Sturtevant WI
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 190° at 4 knots
- Visibility: 10 statute miles
- Sky: scat at 6,000 ft
- Temperature: 84°F (29°C), dew point 57°F (14°C)
- Altimeter: 30.13 inHg
- Observation at 5:45 pm from KUES, 11 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 UNREG the same tail number, which may have belonged to a different aircraft at the time
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.