Stemme GMBH & CO S10 VT accident near Telluride, Colorado, August 24, 2016
On August 24, 2016 at about 8:10 pm local time, a 1997 Stemme GMBH & CO S10 VT (glider), registered N5021, was substantially damaged in an accident during enroute near Telluride, Colorado (Telluride Regional airport). It was a business flight under general aviation rules (Part 91). 2 people were killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot's encounter with a downdraft that exceeded the climb performance of the powered glider and resulted in his inability to maintain clearance from the trees. Contributing to the accident was the pilot's decision to fly near building clouds and rain shower activity.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 24, 2016 · about 8:10 pm local time
- Place
- Telluride, Colorado · Telluride Regional · map
- Type
- Accident
- Injuries
- 2 people were killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Stemme GMBH & CO S10 VT, built 1997 · all S10 VTs on the register
- Registration
- N5021 · no longer on the register · serial 11-010
- Damage
- Substantial damage
- Flight
- Business flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot was conducting a local sightseeing flight at the time of the accident. A witness reported seeing the powered glider climbing out after takeoff and the engine "sounded perfect." He subsequently heard the sound of a "strained engine" similar to a propeller-driven airplane maneuvering during aerobatic flight. Shortly afterward, the sound of the engine stopped. A second witness observed the powered glider fly by with the engine running. It subsequently went out of sight below the tree line. Shortly afterward, he heard a loud noise that he initially attributed to work going on in the area. However, with thoughts of the low flying glider, he decided to drive to a nearby ridge where he observed the accident site. A postaccident examination and engine test run did not reveal any anomalies consistent with a preimpact failure or malfunction. Witness statements and satellite imagery indicated that building cumuliform clouds were present near the accident site. Weather radar data depicted a rain shower over the site about the time of the accident that appeared to be dissipating. With dissipating rain shower activity, the glider was in a favorable area for the existence of downdrafts. It is likely that the pilot encountered a downdraft that exceeded the maximum climb performance of the powered glider.
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
- Miscellaneous/other during enroute defining event
- Other weather encounter during enroute
- Collision with terrain or object (not controlled flight into terrain) during uncontrolled descent
The NTSB's findings
- cause Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
- cause Aircraft › Aircraft oper/perf/capability › Aircraft capability › Climb capability › Capability exceeded
- factor Personnel issues › Action/decision › Info processing/decision › Decision making/judgment › Pilot
- factor Environmental issues › Conditions/weather/phenomena › Ceiling/visibility/precip › (general) › Effect on operation
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instructor: glider; rotorcraft: glider
- Flight time: 4,000 hours in all; 700 in this make and model
- Medical certificate: None
- Seat: left
- Injury: fatal
The aircraft
- Last inspection: annual inspection
- Maximum gross weight: 1,874 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotax 914 (piston); 0 hours total
The flight
- Departed from: TEX Telluride CO at 7:15 pm
- Destination: TEX Telluride CO
- Flight plan: none
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: broken clouds at 9,000 ft; scat at 6,500 ft
- Temperature: 61°F (16°C), dew point 39°F (4°C)
- Altimeter: 30.42 inHg
- Observation at 8:15 pm from TEX, 5 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 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.