Cobalt Aircraft Industries INC Co50 VALKYRIE accident near Atwater, California, September 5, 2017
On September 5, 2017 at about 9:30 pm local time, a 2016 Cobalt Aircraft Industries INC Co50 VALKYRIE, registered N523CA, was substantially damaged in an accident during initial climb near Atwater, California (Castle airport). It was a flight test 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
A loss of aileron effectiveness due to the airplane's design configuration, which resulted in the pilot's inability to control the roll axis and led to a hard landing.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 5, 2017 · about 9:30 pm local time
- Place
- Atwater, California · Castle · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cobalt Aircraft Industries INC Co50 VALKYRIE, built 2016
- Registration
- N523CA · no longer on the register · serial P04
- Damage
- Substantial damage
- Flight
- Flight test · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that the purpose of the flight was to evaluate handling qualities of the experimental airplane at various configurations specified in the test card. After rotation, with the airplane about 50 ft above ground level (agl), the pilot experienced a loss of aileron control. As the airspeed increased, he began to attain some controllability and climbed to about 1,400 ft agl. After about 20 minutes of manipulating the flight controls and practicing climbing and descending using the trim, he stabilized the airplane around 90 kts. He thought that he would be able to land the airplane at an increased airspeed using steady thrust control and the rudder for directional control. During landing, with the airplane about 10 ft above the runway surface, the airplane experienced a loss of lift and landed hard, which resulted in damage to the right wing spar. For the test flight, the airplane manufacturer had changed the winglet position, which contributed to a loss of aileron effectiveness.
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
- Flight control sys malf/fail during initial climb defining event
- Aerodynamic stall/spin during landing (flare/touchdown)
- Hard landing during landing (flare/touchdown)
The NTSB's findings
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Lateral/bank control › Design
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Directional control › Attain/maintain not possible
- cause Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
Pilot
- Certificate: airline transport pilot, flight instructor
- Ratings: multi-engine land; single-engine land; single-engine sea; instructor: glider; instrument: airplane; rotorcraft: glider; rotorcraft: helicopter
- Flight time: 9,650 hours in all; 0.8 in this make and model; 6.3 in the last 90 days; 6.3 in the last 30 days; 7,500 as pilot in command; 3,850 on instruments
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 1 hours
- Last inspection: continuous airworthiness programme, September 4, 2017
- Maximum gross weight: 3,417 lb
- Seats: 5
- Landing gear: retractable
- Engine: Continental Motors TSIOF550-D (piston); 7 hours total
- Operator: Cobalt Aircraft Industries INC
The flight
- Departed from: MER Atwater CA at 9:05 pm
- Destination: MER Atwater CA
- Flight plan: none
- Runway 31, 11,802 ft by 150 ft
Weather at the time
- Light: daylight
- Wind: from 340° at 7 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 75°F (24°C), dew point 64°F (18°C)
- Altimeter: 29.85 inHg
- Observation at 9:15 pm from KMER, 1 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
3 documents, released by the NTSB on February 4, 2020. 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.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot - Aircraft Accident Report, NTSB Form 6120.1 | PDF, 10 pages | View Download |
| 2 | Operator - Aircraft Accident Report, NTSB Form 6120.1 | PDF, 9 pages | View Download |
| 3 | Record of Conversation - Colbalt | PDF, 1 page | View Download |
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.