Mooney M20J accident near Dinsmore, California, July 15, 2021
On July 15, 2021 at about 6:54 pm local time, a Mooney M20J, registered N4474H, was destroyed in an accident during takeoff near Dinsmore, California (Dinsmore airport). It was a personal flight under general aviation rules (Part 91). 4 people were killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The airplane’s degraded engine performance due to wear to the intake cam lobes, which diminished the airplane’s takeoff and climb performance, resulting in a subsequent collision with trees.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 15, 2021 · about 6:54 pm local time
- Place
- Dinsmore, California · Dinsmore · map
- Type
- Accident
- Injuries
- 4 people were killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Mooney M20J · all M20Js on the register
- Registration
- N4474H · no longer on the register · serial 24-0744
- Damage
- Destroyed
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
A witness who was near the departure airport reported observing the airplane circle the area, land on the runway, and stop at the midpoint of the runway. At that time, three people disembarked from the airplane, one of whom walked around the airplane. All three people then boarded the airplane, and the airplane taxied toward the approach end of the runway. The witness observed the airplane take off and stated that the airplane appeared to have rotated just short of the displaced runway threshold. The witness stated that the airplane “barely cleared the fence” and that the rotation was not smooth. Subsequently, the airplane impacted trees just beyond the departure end of the runway, where a postimpact fire ensued. Postaccident examination of the engine revealed that the intake camlobes were worn and exhibited a rounded (instead of an elliptical) shape. The corresponding tappets for the intake cam lobes were galled. The alteration of the camlobe profile will in turn alter the amount and duration of the intake valves opening, thus negatively affecting power output. As a result, takeoff and climb performance would be directly affected. Although the extent of the degradation to the accident engine's power output could not be determined from the available evidence, the degradation was likely sufficient to cause a partial loss of engine power.
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 engine power (partial) during takeoff defining event
- Collision during takeoff/land during takeoff
The NTSB's findings
- Aircraft › Aircraft power plant › Engine (reciprocating) › Recip engine power section › Fatigue/wear/corrosion
- Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Climb rate › Attain/maintain not possible
- Environmental issues › Physical environment › Object/animal/substance › Tree(s) › Contributed to outcome
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: airplane
- Flight time: 2,400 hours in all
- Medical certificate: BasicMed
- Seat: left
- Injury: fatal
Pilot-Rated Passenger
- Flight time: 100 hours in all
- Medical certificate: BasicMed
- Seat: rgt
- Injury: fatal
Passenger
- Seat: left
Passenger
- Seat: rgt
The aircraft
- Last inspection: annual inspection, February 5, 2020
- Maximum gross weight: 2,740 lb
- Seats: 4
- Landing gear: retractable
- Engine: Lycoming IO-360-A3B6D (piston); 0 hours total
- Fire on the ground
The flight
- Flight plan: none
- Runway 9, 2,504 ft by 48 ft
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 300° at 7 knots
- Visibility: 10 statute miles
- Sky: overcast at 500 ft; clear
- Temperature: 54°F (12°C), dew point 54°F (12°C)
- Altimeter: 30.06 inHg
- Observation at 11:35 am from KFOT, 25 miles away
Weather report (METAR): KFOT 151835Z AUTO 30007KT 10SM OVC005 12/12 A3006 RMK AO1
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 3 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
17 documents, released by the NTSB on September 27, 2023. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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.