WPR15CA066 · Ferdon THORP T 18 UNDESIGNAT
Ferdon THORP T 18 UNDESIGNAT · Accident: loss of control in flight during takeoff
From San Rafael Airport (CA35) to Marin County Airport - Gnoss Field (DVO)
Event
- NTSB case
- WPR15CA066
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Ferdon THORP T 18 UNDESIGNAT
- Aircraft type
- Ferdon THORP T 18
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N25VP
- Operator
- Bashforty Glenn
- Onboard fatalities
- Unknown
- Route
- From San Rafael Airport (CA35), San Rafael, CATo Marin County Airport - Gnoss Field (DVO), Novato, CA
- Aircraft age
- About 39 years (built 1975)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Takeoff
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of control in flight
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Personnel issues › Action/decision
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
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.
Probable cause
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.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR15CA066
- Event ID
- 20141220X75830
- Case number
- WPR15CA066
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: cd9e227f365fb31b2849b3c2ae8c50cac22130554eedd1fb86058ac8283d2a36; retrieved 2026-09-16T01:59:18.414Z.