Alisport SILENT 2 accident near Danbury, Connecticut, June 4, 2019
On June 4, 2019 at about 9:00 pm local time, a 2016 Alisport SILENT 2 (glider), registered N66911, was substantially damaged in an accident during approach near Danbury, Connecticut (Danbury Muni 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
The pilot’s inadequate inflight management of the motor glider’s available battery power, which resulted in the inability of the electric motor to provide sufficient thrust to sustain flight in an environment where no atmospheric lift was available.
Source: NTSB aviation accident database, copy made November 2, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 4, 2019 · about 9:00 pm local time · cases in 2019
- Place
- Danbury, Connecticut · Danbury Muni · cases near this airport · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Alisport SILENT 2 ELECTRO, built 2016 · all SILENT 2s on the register
- Registration
- N66911 · no longer on the register · serial 2079
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot was conducting a personal flight in an electrically-powered, self-launching motor glider. He stated that, while returning to the departure airport at the conclusion of the flight, the glider encountered sink and he turned on the electric motor, but it produced “no thrust.” The glider continued to descend and impacted a house about 2 miles from the airport, resulting in substantial damage. The pilot reported that there were no mechanical failures or malfunctions with the glider that would have prevented normal operation before the accident and that the accident might have been prevented with “better management of power and understanding of battery power source.” Data from the engine control unit indicated that the motor was used for about 13 minutes during the taxi, takeoff, and climb. The motor was used again about 5 hours into the flight for about 19 minutes, and again about 5:49 hours elapsed flight time, for about 32 minutes. The final activation of the motor occurred at 6:21 elapsed flight time; the accident occurred at an elapsed flight time of about 6:22. According to the glider manufacturer, the battery supplied power for takeoff and an additional 40 minutes of use thereafter. During the accident flight, the motor was used for a total of over 1 hour. Given this information, it is likely that the pilot had exhausted the available battery power and that the motor was no longer able to provide sufficient thrust to sustain flight.
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 lift during approach
- Fuel exhaustion during approach defining event
The NTSB's findings
- Personnel issues › Action/decision › Info processing/decision › Decision making/judgment › Pilot
- Aircraft › Aircraft systems › Electrical power system › Battery/charger › Incorrect use/operation other cases naming the electrical power
Pilot
- Certificate: private, sport pilot
- Ratings: single-engine land; rotorcraft: glider
- Flight time: 514 hours in all; 10 in the last 90 days; 10 in the last 30 days; 514 as pilot in command
- Last flight review: December 18, 2018
- Medical certificate: Sport Pilot
- Seat: sngl
- Injury: minor injuries
The aircraft
- Airframe total time: 200 hours
- Last inspection: condition inspection, March 5, 2019
- Maximum gross weight: 691 lb
- Seats: 1
- Landing gear: fixed
- Engine: Lz Design FES (electric); 17 hours total
The flight
- Departed from: DXR Danbury CT at 4:30 pm
- Destination: DXR Danbury CT
- Flight plan: VFR
- Runway 26, 4,422 ft by 150 ft
Weather at the time
- Light: daylight
- Wind: from 240° at 11 knots, gusting 16
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 68°F (20°C), dew point 39°F (4°C)
- Altimeter: 30.01 inHg
- Observation at 8:53 pm from dxr, 2 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Photographs from the investigation 3 pictures from the NTSB's docket, as the NTSB released them
Investigative Photographs Peter Wentz Air Safety Investigator Eastern Region Aviation September 18, 2020 Photograph 11 – Accident airplane being removed from residences. 1 Photograph
Photograph 22 – Damaged nose and propeller. Photograph 33 – Damaged propeller. 2 Photograph
Photograph 44 – Instrument panel. 4 PhotographThe NTSB's photographs with the NTSB's captions, at screen size. Open a picture to see it full size or to report one that should not be shown.
Documents from the investigation the NTSB's docket: the evidence folder behind the report
5 documents, released by the NTSB on June 7, 2022. 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/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 12 pages | View Download |
| 2 | Pilot's Statement | PDF, 1 page | View Download |
| 3 | Investigative Photographs | PDF, 3 pages · our copy | View Download |
| 4 | Wreckage Rleaase | PDF, 1 page | View Download |
| 5 | Electronic Data Summary (Fcs and LX9050) | PDF, 15 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
Connections how this case links to the rest of the register
- N66911: not on the register today · the record of its deregistration
- Alisport SILENT 2 19 registered today · the model family and its accident history
- Alisport 24 aircraft on the register
- Engine: Lz Design FES · as the NTSB recorded it
- Danbury Municipal · nearest airport
- Accidents and incidents in Connecticut 522 since 1982 · 68 in the last ten years
- Connecticut 1,612 aircraft registered
The whole map of how records connect · these connections as data: /graph/accident/ERA19LA186.json.
The bigger picture in Aviation Analytics: accidents over time since 1982, by model, by phase of flight and conditions, by place and on the map.
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 does not name anyone involved, its policy at this time. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.