Pilatus B4-PC11 accident near Sterling, Massachusetts, May 20, 2021
On May 20, 2021 at about 8:00 pm local time, a 1976 Pilatus B4-PC11 (glider), registered N65317, was substantially damaged in an accident during approach (VFR pattern final) near Sterling, Massachusetts (Sterling 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 misjudged approach angle which resulted in impact with trees and terrain.
Source: NTSB aviation accident database, copy made November 2, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 20, 2021 · about 8:00 pm local time · cases in 2021
- Place
- Sterling, Massachusetts · Sterling · cases near this airport · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Pilatus B4-PC11, built 1976 · all B4-PC11s on the register
- Registration
- N65317 · registry record · serial 190
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that once on final approach for the runway, he miscalculated his approach angle and found the glider low on altitude and airspeed. The glider then struck trees on the edge of the airport and impacted on the airport surface resulting in substantial damage to the fuselage. The pilot reported no mechanical malfunctions or anomalies that would have precluded normal operation.
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
- Controlled flight into terrain or object (CFIT) during approach (VFR pattern final) defining event
- Miscellaneous/other during approach (VFR pattern final)
The NTSB's findings
- Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
- Personnel issues › Action/decision › Info processing/decision › Identification/recognition › Pilot
- Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Descent/approach/glide path › Not attained/maintained
Pilot
- Certificate: private
- Ratings: single-engine land; rotorcraft: glider
- Flight time: 250 hours in all; 2 in this make and model; 5 in the last 90 days; 4 in the last 30 days; 150 as pilot in command
- Last flight review: April 12, 2021
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: sngl
- Injury: minor injuries
The aircraft
- Airframe total time: 3,589 hours
- Last inspection: annual inspection, May 2, 2021
- Maximum gross weight: 770 lb
- Seats: 1
- Landing gear: fixed
- Operator: Greater Boston Soaring Club INC
The flight
- Flight plan: none
- Runway 16, 3,086 ft by 40 ft
Weather at the time
- Light: daylight
- Wind: from 130° at 6 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 81°F (27°C), dew point 32°F (0°C)
- Altimeter: 30.44 inHg
- Observation at 3:52 pm from KFIT, 8 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Photographs from the investigation 4 pictures from the NTSB's docket, as the NTSB released them
Photo 1 – Left Side View of Glider –
Photo 2 – Rear View of Glider –
Photo 3 – Front View of Glider –
Photo 4 – Close Up of Center Section of Glider –The 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
2 documents, released by the NTSB on January 26, 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, 11 pages | View Download |
| 2 | Photo Array | PDF, 4 pages · our copy | 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
- N65317 on the register today · the tail number may have moved to another aircraft since
- Pilatus B-4 37 registered today · the model family and its accident history
- Pilatus 403 aircraft on the register
- Sterling Airport · nearest airport
- Accidents and incidents in Massachusetts 987 since 1982 · 90 in the last ten years
- Massachusetts 2,646 aircraft registered
The whole map of how records connect · these connections as data: /graph/accident/ERA21LA266.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.