Urban Air Sro UFM-13 accident near Bourne Stage, Texas, June 23, 2009
On June 23, 2009 at about 5:49 pm local time, a Urban Air Sro UFM-13 (glider), registered N17UA, was substantially damaged in an accident during enroute (cruise) near Bourne Stage, Texas. It was a personal flight 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
The pilot’s exceedance of the aircraft’s placarded never-exceed speed (Vne), resulting in aerodynamic flutter in the empennage and the subsequent in-flight structural failure of the aft portion of the fuselage.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 23, 2009 · about 5:49 pm local time
- Place
- Bourne Stage, Texas · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Urban Air Sro UFM-13 Lambada · all UFM-13s on the register
- Registration
- N17UA · no longer on the register · serial 113/13
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot noticed a light fluttering of the rudder pedals that stopped when he applied gentle foot pressure. The motor glider was in level cruise flight when it suddenly began to shake violently, throwing the pilot back and forth against his restraints. He said that the airspeed was about 80 KIAS (knots indicated airspeed); however, data available from the airplane’s on-board Global Positioning System (GPS) indicates that the aircraft was flying approximately 110 KCAS (knots calibrated airspeed). The pilot deployed the emergency ballistic parachute and the aircraft landed gently on top of small trees, sustaining additional damage. Postaccident examination of the motor glider revealed the empennage had separated from the fuselage, but remained attached by control cables and tubing. GPS data showed the aircraft’s airspeed had gradually increased to about 110 KCAS when the in-flight breakup occurred. After a similar accident in the Czech Republic, the never-exceed speed (Vne or redline) was lowered from 119 KCAS to 81 KCAS. The accident airplane’s airspeed indicator had two redlines: one was at 119 knots and the other was taped onto the instrument glass at 81 knots and was in the middle of the green arc. The pilot said that he was not aware that the Vne speed was 81 KCAS, but that the change was a temporary flight recommendation from the manufacturer. He said that he had received the memorandum containing the temporary restriction on airspeed not to exceed 81 KCAS in any configuration, but that he “did not think the 81 knots was a Vne speed.” The manufacturer had lowered the Vne as a temporary measure because of a previous accident where an in-flight structural failure of the aft portion of the fuselage occurred. The investigation of the first accident by Air Accident Investigations Institute, Republic of Czechoslovakia, determined that the separation was the result of aerodynamic flutter in the empennage. According to the NTSB’s Materials Laboratory report, the fractures were consistent with compressive loads and tension or tearing from local bending. No evidence of manufacturing errors or preaccident damage was noted.
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
- Aircraft structural failure during enroute (cruise) defining event
The NTSB's findings
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Airspeed › Capability exceeded
- cause Aircraft › Aircraft structures › Fuselage › Fuselage main structure › Failure
- cause Personnel issues › Action/decision › Action › Incorrect action performance › Pilot
Pilot
- Certificate: private
- Ratings: single-engine land; instrument: airplane; rotorcraft: glider
- Flight time: 633 hours in all; 11 in this make and model; 10 in the last 90 days; 9 in the last 30 days; 559 as pilot in command
- Seat: left
- Injury: no injuries
The aircraft
- Maximum gross weight: 1,320 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotax 912ULS (piston); 0 hours total
- Operator: San Antonio Light Sport Aircraft, Inc.
The flight
- Departed from: 5C1 Boerne Stage TX at 5:02 pm
- Destination: 5C1 Boerne Stage TX
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 140° at 5 knots
- Visibility: 10 statute miles
- Sky: a few clouds at 6,000 ft
- Temperature: 91°F (33°C), dew point 64°F (18°C)
- Altimeter: 29.92 inHg
- Observation at 5:53 pm from SAT, 13 miles away
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.