Schleicher ASW-20C accident near Unionville, Pennsylvania, May 9, 2010
On May 9, 2010 at about 4:44 pm local time, a Schleicher ASW-20C (glider), registered N6BF, was substantially damaged in an accident during maneuvering (low-alt flying) near Unionville, Pennsylvania. 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's lack of remedial action in response to a loss of altitude, which led to a forced landing in unsuitable terrain.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 9, 2010 · about 4:44 pm local time
- Place
- Unionville, Pennsylvania · map
- Type
- Accident
- Injuries
- 1 person was seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Schleicher ASW-20C · all ASW-20Cs on the register
- Registration
- N6BF · no longer on the register · serial 20832
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
According to the glider pilot, the flight was intended as a local recreational flight. He planned to climb via thermals to get across a five-mile gap between ridges, but was unable to gain altitude. He then attempted to turn to a "spur" that was separate from the main ridge to gain lift, but while performing the maneuvers the glider continued to lose altitude in a downdraft. The glider subsequently impacted trees and came to rest inverted, seriously injuring the pilot. The pilot reported that there were no mechanical problems with the glider. He stated that, in retrospect, he should have released the 10 gallons of water ballast in each wing and deployed positive flaps. A weather observation taken 35 miles from the accident site, approximately at the time of the accident, recorded the wind from 301 degrees at 13 knots, gusting to 20 knots.
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 maneuvering (low-alt flying) defining event
- Collision with terrain or object (not controlled flight into terrain) during uncontrolled descent
The NTSB's findings
- cause Personnel issues › Action/decision › Action › Lack of action › Pilot
- Environmental issues › Conditions/weather/phenomena › Wind › Downdraft › Effect on equipment
Pilot
- Certificate: private
- Ratings: single-engine land; instrument: airplane; rotorcraft: glider
- Flight time: 2,500 hours in all; 500 in this make and model; 20 in the last 90 days; 4 in the last 30 days
- Last flight review: January 23, 2010
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: sngl
- Injury: serious injuries
The aircraft
- Airframe total time: 1,000 hours
- Last inspection: annual inspection, April 20, 2010
- Maximum gross weight: 1,001 lb
- Seats: 1
- Landing gear: retractable
The flight
- Departed from: 79N Unionville PA at 4:00 pm
- Destination: 79N Unionville PA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 290° at 13 knots, gusting 20
- Visibility: 10 statute miles
- Sky: overcast at 4,400 ft
- Temperature: 43°F (6°C), dew point 28°F (-2°C)
- Altimeter: 30.09 inHg
- Observation at 4:40 pm from KUNV, 35 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.
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number ERA10CA260.