Caproni Vizzola Cos. Aero. Calif A-21 accident near San Antonio, Texas, June 10, 2006
On June 10, 2006, a Caproni Vizzola Cos. Aero. Calif A-21 (glider), registered N9FM, was substantially damaged in an accident near San Antonio, Texas (San Geronimo airport). It was a personal flight under general aviation rules (Part 91). 1 person was seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot/owner's failure to properly secure the right wing, which resulted in the in-flight separation of the right wing.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 10, 2006
- Place
- San Antonio, Texas · San Geronimo · map
- Type
- Accident
- Injuries
- 1 person was seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Caproni Vizzola Cos. Aero. Calif A-21
- Registration
- N9FM · no longer on the register · serial 205
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
A bystander used a video camera to record the flight from the ground. A review of the video revealed that when the tow airplane and glider were on their takeoff roll, the glider's right wing deflected upwards (about 90 degrees) and completely separated at the wing-to-fuselage attachment point. The glider pilot simultaneously released the tow connection, as the glider descended back onto the runway and then veered to the right and out of camera view. The 2,500-hour commercial glider pilot had recently purchased the glider and he (and three others) helped him attach both wings four days prior to the accident. The pilot reported that while his associates held the wings, he used the manufacturer supplied Allen wrench and inserted it into the hexagonal hole on top of the wing, which house the wing-attachment mechanism that was mounted vertically to the inboard stub of the wing. The pilot reported that he made 15 complete revolutions of the wrench, which fully engaged the locking pins that run symmetrically along a jackscrew. The pilot visually confirmed that the top locking pin was flush with the plane of the top attachment ring. He also shook both wings to make sure they were secured. Prior to the first flight, the pilot performed a preflight inspection and he once again confirmed that the wing-to-fuselage attaching pins were fully engaged. He departed about five minutes later. Examination of the glider by a Federal Aviation Administration (FAA) inspector revealed that the wing-to-fuselage locking mechanism was not fully engaged. The inspector used the same Allen wrench that was used to install the wings and manually tested the locking mechanism. When the inspector inserted the wrench, the system moved freely and he was able to make 15 complete revolutions, which fully engaged the locking pins.
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
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: single-engine land; instructor: glider; rotorcraft: glider
- Flight time: 2,500 hours in all; 25 in this make and model; 290 in the last 90 days; 77 in the last 30 days
- Medical certificate: Class 2
- Injury: serious injuries
The aircraft
- Landing gear: fixed
- Engine:; 0 hours total
The flight
- Departed from: 8T8 San Antonio TX
- Destination: 8T8
- Flight plan: none
- Runway 17
Weather at the time
- Light: daylight
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| 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.