# NTSB ERA17LA048: Schweizer SGS126, N65968, Moscow, TN, November 17, 2016 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: November 17, 2016, 14:30 local (20:30 UTC) - Place: Moscow, TN - Coordinates: 35.128612, -89.355834 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.1286&lon=-89.3558&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach-VFR pattern base: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report January 25, 2018 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA FSDO - NTSB case key (mKey): 94393 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA17LA048 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/94393/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=94393 - Page: https://openairdocs.org/ntsb/ERA17LA048 ## Probable cause The pilot's failure to maintain adequate airspeed and his exceedance of the glider’s critical angle of attack while maneuvering at low altitude, which resulted in an aerodynamic stall/spin. ## 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: [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/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: [All aircraft, 990 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md) - [Object/animal/substance: tree(s)](https://openairdocs.org/ntsb-findings/03022020): Environmental issues › Physical environment · Contributed to outcome; cases with it: [All aircraft, 933 cases](https://openairdocs.org/ntsb-findings/03022020/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 base: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241) (defining event); cases with it: [All aircraft, 1,529 cases](https://openairdocs.org/ntsb-events/241/sequence.md) ## Analysis A tow plane pilot on the ground reported that he watched the glider fly for about 20 minutes after it was released from the tow plane. After the glider turned onto the left downwind approach to land and while about 300 ft above ground level (agl), he saw the glider enter a right 360° turn while on the base leg, followed shortly after by a 180° right turn. The glider then entered an aerodynamic stall/spin from about 100 ft agl and descended into trees. Although the glider pilot stated that he was unable to recall the sequence of events that occurred after entering the traffic pattern, he did not believe that there were any mechanical anomalies with the glider that would have precluded normal operation. It is likely that the pilot did not maintain adequate airspeed and exceeded the glider's critical angle of attack, which resulted in the aerodynamic stall/spin. ## Factual narrative On November 17, 2016, about 1430 central standard time, a Schweitzer SGS 1-26E glider, N65968, was substantially damaged when it impact trees and terrain while maneuvering in the airport traffic pattern at Hawks Nest Airport (4TN3), Moscow, Tennessee. The airline transport pilot sustained serious injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight, which was operated under the provisions of Title 14 Code of Federal Regulations Part 91. After an aerial tow to 3,000 feet above ground level (agl) the glider disconnected from the tow plane and the pilot flew for approximately 20 minutes between an altitude of 2,500 and 3,000 feet agl. A tow plane pilot, who witnessed the accident from the ground, observed the glider flight for approximately 20 minutes. He observed the glider enter a normal left downwind approach to runway 18. He further stated that he observed the glider execute a 360-degree right turn while on the base leg at about 300 feet agl. He reported that after the 360-degree turn, the glider made another 180-degree right turn which appeared to "develop into a slow spin" from about 100 feet agl; the glider descended into the trees. The pilot stated he could not recall the left base turn and had no recollection of the accident, but offered the possibility of wind shear as a cause. In addition, he indicated that he possibly made the turn to lose altitude. He further stated there were no mechanical irregularities or anomalies with the glider. Post-accident examination by a Federal Aviation Administration (FAA) inspector revealed the glider was upright and level on flat ground with both left and right wing leading edges pushed up against trees in an area approximately one quarter of a mile northeast of runway 18. Both wings were partially detached from the fuselage and 4 feet of the left outboard wing was crumpled. The right wing was crumpled and nearly severed mid-span. The empennage and rudder remained attached to the airframe and the cockpit sustained minor damage. The pilot held an airline transport pilot certificate with a rating for airplane single-engine land, multi engine land, and glider. His most recent FAA first-class medical certificate was issued on September 6, 2016. At the time of the accident, he reported a total flight experience of 8,500 hours total time with 17.4 hours in a glider and 1.6 hours in this make and model. The single-seat, mid-wing, glider, serial number 608, was manufactured in 1974. Its most recent annual inspection was completed on December 15, 2015. At that time, the airframe had accumulated approximately 2,709 total hours of operation. The glider's flight manual detailed that its stalling speed in level flight was 28 mph. At a 20-degree bank, it was 29 mph, and at 30 and 45 degrees, it was 30 and 33.4 mph respectively. The William L Whitehurst Field Airport (M08) Bolivar, Tennessee was located about 17 miles south of the accident site. The recordedweather at MJX, at 1425, was wind from 170 degrees at 7 knots, gusting to 14 knots, and a clear sky. The temperature was 27 degrees C; dew point 06 degrees C, and the altimeter setting was 29.97 inches Hg. An hour before the accident through an hour after, the winds remained steady from 170 degrees at 7 knots with gusts up to 15 knots. ## Aircraft - Registration: N65968 (not matched to a registry record) - Reported make and model: SCHWEIZER SGS126 (E) - Category: Glider - Serial number: 608 - Year built: 1974 - Airframe hours: 2709 - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, December 15, 2015 - Departed: 4TN3, MOSCOW, TN - Destination: 4TN3, MOSCOW, TN - Airport: 4TN3, Hawks Nest, runway 18, 4,000 × 60 ft, grass/turf - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 52; injuries: serious; flight engineer, airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; seat: single; restraint: 3-point; flight hours: 8,500 total, 1.6 in this make and model, 82 in the last 90 days, 29.6 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 170° at 7 knots, gusting 14 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 43 °F - Altimeter: 29.96 inHg - Observed at: KMO8, 17 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 20161117023799A](https://openairdocs.org/incident/20161117023799A), Nov 17, 2016: Schweizer SGS 1-26E, Moscow, TN, Destroyed. [privacy data omitted] Piloted glider N65968 on 11/17/16. At approach to n. runway 18, Hawks Nest Airport in Moscow, TN, he executed a 360 degree turn causing… ## Docket (8 files) The files NTSB released with the investigation on October 20, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=94393. 3.8 MB in all. - Memo for Record - Pilot Report (item 1, .PDF, 211 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457226&FileExtension=.PDF&FileName=Memo%20for%20Record%20-%20Pilot%20Report-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 2, .PDF, 813 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457227&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Weather Reports and Records (item 3, .PDF, 346 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457228&FileExtension=.PDF&FileName=Weather%20Reports%20and%20Records-Master.PDF - Witness Statement (item 4, .PDF, 210 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457229&FileExtension=.PDF&FileName=Witness%20Statement-Master.PDF - Pilot Memorandum of Conversation (item 5, .PDF, 97 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457230&FileExtension=.PDF&FileName=Pilot%20Memorandum%20of%20Conversation-Master.PDF - Airport and Accident Site Overview (item 6, .PDF, 386 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457231&FileExtension=.PDF&FileName=Airport%20and%20Accident%20Site%20Overview-Master.PDF - Accident Site and Damage Photographs (item 7, .PDF, 4 photos, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457232&FileExtension=.PDF&FileName=Accident%20Site%20and%20Damage%20Photographs-Master.PDF - Flight Manual Excerpt - Stall Speeds (item 8, .PDF, 143 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457233&FileExtension=.PDF&FileName=Flight%20Manual%20Excerpt%20-%20Stall%20Speeds-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.