Amateur-built KIT FOX CL accident near Boulder, Colorado, November 24, 2008
On November 24, 2008 at about 7:45 pm local time, a amateur-built KIT FOX CL, registered N4JU, was substantially damaged in an accident during initial climb near Boulder, Colorado (Boulder Muncipal Airport). It was a personal flight under general aviation rules (Part 91). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A loss of engine thrust due to the pilot's inadvertent activation of the propeller controls. Contributing to the accident were the non-standard propeller controls and the pilot's lack of experience in the airplane.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 24, 2008 · about 7:45 pm local time
- Place
- Boulder, Colorado · Boulder Muncipal Airport · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built KIT FOX CL
- Registration
- N4JU · no longer on the register · serial C9407-0041
- 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 when he was taking off on his first solo flight in the recently purchased airplane, the electrically operated propeller started to increase pitch. The pilot stated that he tried to decrease the pitch, but each time he released the control-stick-mounted propeller button, the propeller pitch would increase. After the prop went to a high pitch angle and the engine started to run "rough," the pilot elected to conduct a forced landing and turn back to the runway. A Certified Flight Instructor (CFI), who flew with the accident pilot on two previous flights, reported that the propeller controls for pitch are two buttons on the top end of the control stick (one to increase and the other to decrease pitch). He added that it was easy to inadvertently touch and to confuse which button increased and which button decreased propeller pitch. The CFI also noted that it was easy to confuse the propeller pitch buttons with similar elevator trim buttons located on the control stick. The CFI added that on several occasions he and the accident pilot mistakenly actuated the propeller control the wrong way. During the second flight with the accident pilot, the CFI said that they planned to practice takeoffs and landings. During the session, the CFI accidentally coarsened the prop pitch to its maximum setting; the power loss was "large", and the CFI closed the throttle and landed. Furthermore, the CFI reported that he had to intervene in "all, except one of the landings and most of the take-offs, performed by the accident pilot." The CFI reported that he told the accident pilot that he thought that he needed much more than two hours of dual instruction required by the insurance company.
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
- Miscellaneous/other during initial climb
- Loss of engine power (partial) during initial climb defining event
- Off-field or emergency landing during initial climb
- Controlled flight into terrain or object (CFIT) during initial climb
The NTSB's findings
- cause Aircraft › Aircraft propeller/rotor › Propeller system › Propeller controlling system › Unintentional use/operation
- factor Aircraft › Aircraft propeller/rotor › Propeller system › Propeller controlling system › Design
- factor Personnel issues › Experience/knowledge › Experience/qualifications › Total experience w/ equipment › Pilot
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; single-engine sea; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 1,700 hours in all; 2 in this make and model
- Last flight review: May 11, 2008
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: frt
- Injury: minor injuries
The aircraft
- Airframe total time: 114 hours
- Last inspection: condition inspection, November 3, 2008
- Seats: 2
- Landing gear: fixed
- Engine: Nsi Subaru (piston); 0 hours total
- Fire on the ground
The flight
- Departed from: KBDU Bolder CO
- Destination: Grand Rapids MN
- Flight plan: not recorded
Weather at the time
- Light: dawn
- Wind: from 180° at 8 knots
- Visibility: 60 statute miles
- Sky: a few clouds at 25,000 ft
- Temperature: 61°F (16°C), dew point -9°F (-23°C)
- Altimeter: 30.22 inHg
- Observation at 7:46 pm from KBJC
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.