# NTSB ERA21LA266: Pilatus B4-PC11, N65317, Sterling, MA, May 20, 2021 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 4 · Limited · Final report - Date: May 20, 2021, 16:00 local (20:00 UTC) - Place: Sterling, MA · Trees off end of runway 16. - Coordinates: 42.425917, -71.792861 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=42.4259&lon=-71.7929&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach-VFR pattern final: Controlled flight into terr/obj (CFIT)](https://openairdocs.org/ntsb-events/120) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 4 - Basic report with no Prelim publish - NTSB office: Eastern Region Aviation - Parties: FAA / FSDO - NTSB case key (mKey): 103328 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA21LA266 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103328/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103328 - Page: https://openairdocs.org/ntsb/ERA21LA266 ## Probable cause The pilot’s misjudged approach angle which resulted in impact with trees and terrain. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Pilatus B4-PC11, 1 case](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=7090104), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Info processing/decision: identification/recognition](https://openairdocs.org/ntsb-findings/02041510): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Pilatus B4-PC11, 1 case](https://openairdocs.org/ntsb-findings/02041510/cases.md?model=7090104), [All aircraft, 559 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md) - [Performance/control parameters: descent/approach/glide path](https://openairdocs.org/ntsb-findings/01062040): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Pilatus B4-PC11, 1 case](https://openairdocs.org/ntsb-findings/01062040/cases.md?model=7090104), [All aircraft, 809 cases](https://openairdocs.org/ntsb-findings/01062040/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach-VFR pattern final: Miscellaneous/other](https://openairdocs.org/ntsb-events/900); cases with it: [Pilatus B4-PC11, 1 case](https://openairdocs.org/ntsb-events/900/sequence.md?model=7090104), [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) - [Approach-VFR pattern final: Controlled flight into terr/obj (CFIT)](https://openairdocs.org/ntsb-events/120) (defining event); cases with it: [Pilatus B4-PC11, 1 case](https://openairdocs.org/ntsb-events/120/sequence.md?model=7090104), [All aircraft, 1,074 cases](https://openairdocs.org/ntsb-events/120/sequence.md) ## Analysis 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. ## Aircraft - Registration: [N65317](https://openairdocs.org/aircraft/N65317), registered now, S/N 190, built 1976 (OpenAirDocs) - Reported make and model: PILATUS B4-PC11 - Registry model: [Pilatus B4-PC11](https://openairdocs.org/model/pilatus-b4-pc11) (registry code 7090104) (OpenAirDocs) - Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs) - Category: Glider - Serial number: 190 - Year built: 1976 - Airframe hours: 3589 - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Greater Boston Soaring Club Inc - Registered owner: Greater Boston Soaring Club Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, May 2, 2021 - Destination: Same as departure - Airport: 3B3, Sterling, runway 16, 3,086 × 40 ft, grass/turf - Equipment: Data recorder ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 62; injuries: minor; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review April 12, 2021; seat: single; restraint: 5-point; flight hours: 250 total, 2 in this make and model, 150 as pilot in command, 5 in the last 90 days, 4 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 130° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 32 °F - Altimeter: 30.44 inHg - Observed at: KFIT, 8 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20210520009579A](https://openairdocs.org/incident/20210520009579A), May 20, 2021: Pilatus B4-PC11, Sterling, MA, Substantial damage. N65317, Pilatus B4-P11, single seat glider piloted by [privacy data omitted] struck trees while attempting to land on runway 16 at K3B3 Sterling Airport… ## Docket (2 files) The files NTSB released with the investigation on January 26, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103328. 2.9 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12762050&FileExtension=pdf&FileName=6120_1web_VT2_Redacted-Rel.pdf - Photo array (item 2, PDF, 4 pages, 749 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12768551&FileExtension=pdf&FileName=Photo%20Array-Rel.pdf From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.