# NTSB ERA20CA116: Let L 23 Super Blanik, N296BA, Huntsville, AL, March 1, 2020 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Data collection · Final report - Date: March 1, 2020, 14:00 local (20:00 UTC) - Place: Huntsville, AL - Coordinates: 34.747222, -86.46083 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.7472&lon=-86.4608&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach: Loss of control in flight](https://openairdocs.org/ntsb-events/240) - Highest injury: Serious injuries - Injuries: 2 serious - Status: Completed, report June 29, 2020 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 101021 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA20CA116 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101021/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101021 - Page: https://openairdocs.org/ntsb/ERA20CA116 ## Probable cause The pilot's failure to maintain glider control and his exceedance of the glider's critical angle of attack while maneuvering in gusting wind conditions, which resulted in an aerodynamic stall. ## 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: [Let L-23 SUPER BLANIK, 10 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=1360308), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: angle of attack](https://openairdocs.org/ntsb-findings/01062042): Aircraft › Aircraft oper/perf/capability · Capability exceeded (probable cause); cases with it: [Let L-23 SUPER BLANIK, 5 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md?model=1360308), [All aircraft, 990 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md) - [Wind: gusts](https://openairdocs.org/ntsb-findings/03034045): Environmental issues › Conditions/weather/phenomena · Effect on operation (probable cause); cases with it: [Let L-23 SUPER BLANIK, 1 case](https://openairdocs.org/ntsb-findings/03034045/cases.md?model=1360308), [All aircraft, 1,199 cases](https://openairdocs.org/ntsb-findings/03034045/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach: Other weather encounter](https://openairdocs.org/ntsb-events/400); cases with it: [Let L-23 SUPER BLANIK, 3 cases](https://openairdocs.org/ntsb-events/400/sequence.md?model=1360308), [All aircraft, 1,127 cases](https://openairdocs.org/ntsb-events/400/sequence.md) - [Approach: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Let L-23 SUPER BLANIK, 3 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=1360308), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Approach: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Let L-23 SUPER BLANIK, 10 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=1360308), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis According to the glider pilot, the purpose of the flight was to release from the tow about 300 ft above ground level, return to the airport, and land on the departure runway in the opposite direction, which would simulate the response to a "rope-break" emergency during the initial climb. After departure from the runway and release from the tow, the pilot completed a 270° turn on the north side of the runway and had to make another 90°, left base-to-final turn to return toward the runway. While still on the base leg, the glider encountered an 11-knot wind from the south, gusting to 18 knots. The pilot believed that the glider must have encountered "wind shear" as he "lost all elevator control," and the glider then impacted terrain. The Federal Aviation Administration inspector who conducted a postaccident examination of the glider reported that he established flight control continuity. The pilot reported that there were no preaccident mechanical malfunctions or failures with the glider that would have precluded normal operation. ## Factual narrative According to the glider pilot, the purpose of the flight was to release from the tow about 300 ft above ground level, return to the airport, and land on the departure runway in the opposite direction, which would simulate the response to a "rope-break" emergency during the initial climb. After departure from runway 27 and release from the tow, the pilot completed a 270° turn (to his right) on the north side of the runway and had a 90°, left base-to-final turn remaining to return to the runway. While still on the base leg, the glider encountered an 11-knot wind from the south that gusted to 18 knots, and the pilot surmised that he must have encountered "wind shear" as he "lost all elevator control" and impacted terrain.Postaccident examination of the flight control system did not reveal any anomalies and the pilot reported that there were no preimpact mechanical malfunctions or failures with the glider that would have precluded normal operation. ## Aircraft - Registration: [N296BA](https://openairdocs.org/deregistered/N296BA-2022-02-05), registration cancelled 2022-02-05, S/N 948117, built 1994 (OpenAirDocs) - Reported make and model: Let L 23 SUPER BLANIK (No Series) - Registry model: [Let L-23 SUPER BLANIK](https://openairdocs.org/model/let-l-23-super-blanik) (registry code 1360308) (OpenAirDocs) - Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs) - Category: Glider - Serial number: 948117 - Year built: 1994 - Airframe hours: 1680 - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Huntsville Soaring Club - Registered owner: Huntsville Soaring Club - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 30, 2019, 90 hours before - Departed: 3M5, Huntsville, AL - Destination: 3M5, Huntsville, AL - Airport: 3M5, Moontown, runway 09, 2,180 × 160 ft, grass/turf - Equipment: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 69; injuries: serious; private, commercial, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; seat: rear; restraint: 4-point; flight hours: 1,834 total, 295 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 11 knots, gusting 18 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 66 °F, dew point 37 °F - Altimeter: 30.12 inHg - Observed at: KMDQ, 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 20200301006099A](https://openairdocs.org/incident/20200301006099A), Mar 1, 2020: Let L-23 SUPER BLANIK, Brownsboro, AL, Substantial damage. The glider departed runway 27 under aerotow to accomplish a planned premature termination of tow for a training demonstration. The tow rope was released at… ## Docket (5 files) The files NTSB released with the investigation on April 23, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101021. 5.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 745 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40482965&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Witness Statements (item 2, .PDF, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40482966&FileExtension=.PDF&FileName=Witness%20Statements-Master.PDF - FAA Inspector's Statement (item 3, .PDF, 127 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40482967&FileExtension=.PDF&FileName=FAA%20Inspector%27s%20Statement-Master.PDF - Memorandum for Record Flight Control Exam (item 4, .PDF, 53 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40482968&FileExtension=.PDF&FileName=Memorandum%20for%20Record%20Flight%20Control%20Exam-Master.PDF - Investigation Photos (item 5, .PDF, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40482969&FileExtension=.PDF&FileName=Investigation%20Photos-Master.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.