# NTSB ERA11CA087: Schweizer SGS 1-23D, N91896, Aberdeen, MD, December 11, 2010 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Data collection · Final report - Date: December 11, 2010, 15:30 local (20:30 UTC) - Place: Aberdeen, MD - Coordinates: 39.552223, -76.195556 - Nearby events: https://openairdocs.org/map.md?lat=39.5522&lon=-76.1956&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-aerobatics: Loss of control in flight](https://openairdocs.org/ntsb-events/240) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report June 8, 2011 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 77992 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA11CA087 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/77992/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=77992 - Page: https://openairdocs.org/ntsb/ERA11CA087 ## Probable cause The pilot's loss of control during an intentional aerobatic maneuver (spin) resulting in a collision with trees. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Action: incorrect action performance](https://openairdocs.org/ntsb-findings/02041015): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Schweizer SGS 1-23D, 1 case](https://openairdocs.org/ntsb-findings/02041015/cases.md?model=8050104), [All aircraft, 1,386 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md) - [Aircraft](https://openairdocs.org/ntsb-findings/01060000): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Schweizer SGS 1-23D, 1 case](https://openairdocs.org/ntsb-findings/01060000/cases.md?model=8050104), [All aircraft, 63 cases](https://openairdocs.org/ntsb-findings/01060000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-aerobatics: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241); cases with it: [Schweizer SGS 1-23D, 1 case](https://openairdocs.org/ntsb-events/241/sequence.md?model=8050104), [All aircraft, 1,529 cases](https://openairdocs.org/ntsb-events/241/sequence.md) - [Maneuvering-aerobatics: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Schweizer SGS 1-23D, 1 case](https://openairdocs.org/ntsb-events/240/sequence.md?model=8050104), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Schweizer SGS 1-23D, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=8050104), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis According to the pilot, on his second flight of the day, he initiated a spin to the right around 3,200 feet. After approximately three-quarters of a turn, he attempted to recover from the spin by applying left rudder. He felt no resistance upon application of the rudder and the glider felt unresponsive. As he neared the ground, the pilot was able to maneuver toward trees. The glider impacted a tree, resulting in substantial damage to the wings. The glider remained in the tree for several days due to snow and ice storms before it could be recovered. A postaccident examination by a Federal Aviation Administration inspector revealed that the rudder turnbuckles were set per the maintenance manual and the rudder return springs were intact and not stretched. The rudder controls functioned properly when manipulated. ## Factual narrative According to the pilot of the glider, on his second flight of the day, he initiated a spin to the right around 3,200 feet. After approximately three-quarters of a turn, the pilot attempted to recover from the spin by applying left rudder. The pilot stated that he felt no resistance upon application of the rudder, and that the glider was unresponsive. As he neared the ground, the pilot was able to maneuver toward trees. The glider impacted a tree, resulting in substantial damage to the wings. The glider remained in the tree for several days due to snow and ice storms before it could be recovered. Post accident examination by a Federal Aviation Administration Inspector revealed that the rudder turnbuckles were set per the manual and the rudder return springs were intact and not stretched. The rudder controls functioned properly when manipulated. ## Aircraft - Registration: [N91896](https://openairdocs.org/aircraft/N91896), registered now, S/N 28, built 1955 (OpenAirDocs) - Reported make and model: SCHWEIZER SGS 1-23D - Registry model: [Schweizer SGS 1-23D](https://openairdocs.org/model/schweizer-sgs-1-23d) (registry code 8050104) (OpenAirDocs) - Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs) - Category: Glider - Serial number: 28 - Airframe hours: 1117 - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Atlantic Soaring Club Inc - Registered owner: Atlantic Soaring Club Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 20, 2010 - Departed: 0W3, Aberdeen, MD - Destination: 0W3, Aberdeen, MD - Airport: 0W3, Harford County Airport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 68; injuries: none; private; airplane ratings: single-engine land; last flight review May 15, 2010; seat: single; flight hours: 600 total, 100 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 80° at 3 knots - Visibility: 7 statute miles - Lowest ceiling: 10,000 ft overcast - Temperature: 41 °F, dew point 30 °F - Altimeter: 30.20 inHg - Observed at: MTN, 18 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 20101211052949A](https://openairdocs.org/incident/20101211052949A), Dec 11, 2010: Schweizer SGS 1-23D, Churchville, MD, Substantial damage. Pilot was practicing spins. Did not recover from spin and collided with trees. Aircraft received substantial damage. Pilot was not injured. ## Docket (5 files) The files NTSB released with the investigation on April 29, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=77992. 538 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 403 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40342540&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Pilot Interview Summary (item 2, .PDF, 26 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40342538&FileExtension=.PDF&FileName=Pilot%20Interview%20Summary-Redacted.PDF - FAA Inspector Statement (item 3, .PDF, 46 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40342539&FileExtension=.PDF&FileName=FAA%20Inspector%20Statement-Redacted.PDF - Memorandum for Record - Pilot Interview (item 4, .PDF, 25 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40342551&FileExtension=.PDF&FileName=Memorandum%20for%20Record%20-%20Pilot%20Interview-Master.PDF - Rental Agreement Excerpt (item 5, .PDF, 37 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40342550&FileExtension=.PDF&FileName=Rental%20Agreement%20Excerpt-Redacted.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.