Ferdon THORP T 18 accident near San Rafael, California, December 20, 2014
On December 20, 2014 at about 8:30 pm local time, a 1975 Ferdon THORP T 18, registered N25VP, was substantially damaged in an accident during takeoff near San Rafael, California (San Rafael 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 pilot's delayed decision to abort the takeoff. Contributing to the accident are an inadequate modification to the seat position, and the pilot's failure to check flight controls for freedom and correct movement.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- December 20, 2014 · about 8:30 pm local time
- Place
- San Rafael, California · San Rafael · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Ferdon THORP T 18 UNDESIGNAT, built 1975
- Registration
- N25VP · no longer on the register · serial 07
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that prior to the flight in the experimental airplane, he unbolted and rebolted the pilot's seat from its middle position to the forward position. He did not check to see if the flight control stick movement would be restricted in this new configuration. During the takeoff roll, the airplane would not rotate when he moved the flight control stick aft. Not realizing the seat prevented the flight control stick movement to the full aft position, the pilot adjusted the elevator trim and the airplane subsequently lifted off, however, it would not climb. The pilot then aborted the takeoff; however, the airplane did not have sufficient distance to stop. It departed the runway surface and traversed through a field, impacted trees, and came to rest inverted. The airplane sustained substantial damage to the wings, rudder, and vertical stabilator. The pilot reported no preimpact mechanical malfunctions or failures with the airframe or engine that would have precluded normal operation.
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 takeoff defining event
- Collision with terrain or object (not controlled flight into terrain) during takeoff (rejected takeoff)
- Runway excursion during takeoff (rejected takeoff)
The NTSB's findings
- cause Personnel issues › Action/decision › Action › Delayed action › Pilot
- factor Personnel issues › Task performance › Inspection › Preflight inspection › Pilot
- factor Personnel issues › Task performance › Maintenance › Modification/alteration › Pilot
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 1,530 hours in all; 9 in this make and model
- Last flight review: January 6, 2014
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 1,570 hours
- Last inspection: annual inspection, September 9, 2014
- Maximum gross weight: 1,600 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming O-290-D2 (piston); 0 hours total
The flight
- Departed from: CA35 San Rafael CA at 8:44 pm
- Destination: DVO Novato CA
- Flight plan: none
- Runway 04, 2,140 ft by 30 ft
Weather at the time
- Light: daylight
- Visibility: 7 statute miles
- Sky: broken clouds at 3,500 ft; clear
- Temperature: 64°F (18°C), dew point 0°F (-18°C)
- Altimeter: 29.92 inHg
- Observation at 7:35 pm from KDVO, 6 miles away
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.