# NTSB WPR09LA381: Schempp Hirth Discus CS, N7HV, Williams, CA, August 2, 2009 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: August 2, 2009, 11:39 local (18:39 UTC) - Place: Williams, CA - Coordinates: 39.071109, -122.027221 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.0711&lon=-122.0272&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Glider tow event](https://openairdocs.org/ntsb-events/510) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report December 15, 2009 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 74437 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR09LA381 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/74437/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=74437 - Page: https://openairdocs.org/ntsb/WPR09LA381 ## Probable cause The pilot's failure to maintain clearance with terrain after intentionally releasing from the tow plane at a low altitude during the initial climb. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters](https://openairdocs.org/ntsb-findings/01062000): Aircraft › Aircraft oper/perf/capability · Incorrect use/operation (probable cause); cases with it: [Schempp-Hirth DISCUS CS, 1 case](https://openairdocs.org/ntsb-findings/01062000/cases.md?model=38019VS), [All aircraft, 1,269 cases](https://openairdocs.org/ntsb-findings/01062000/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Schempp-Hirth DISCUS CS, 1 case](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=38019VS), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Glider tow event](https://openairdocs.org/ntsb-events/510) (defining event); cases with it: [Schempp-Hirth DISCUS CS, 1 case](https://openairdocs.org/ntsb-events/510/sequence.md?model=38019VS), [All aircraft, 45 cases](https://openairdocs.org/ntsb-events/510/sequence.md) - [Maneuvering: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Schempp-Hirth DISCUS CS, 2 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=38019VS), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis After taking off, the lead pilot in a dual tow elected to perform a precautionary release as a result of a "slack-line" condition. The trail pilot, realizing that his tow rope was now under the lead pilot's right wing, released his tow rope and immediately turned right. Without sufficient altitude or airspeed to return to the airport, the trail pilot tried to level the glider's wings, but could not before the right wing tip impacted terrain. The glider sustained substantial damage to its right wing and empennage. ## Factual narrative On August 2, 2009, about 1139 Pacific daylight time, a Schempp-Hirth Discus CS glider, N7HV, collided with terrain while maneuvering near the Williams Gliderport (CN12), Williams, California. The private pilot, the sole occupant, received serious injuries. The glider sustained substantial damage. Visual meteorological conditions prevailed for the local flight, which was conducted in accordance with Title 14 Code of Federal Regulations (CFR) Part 91, and a flight plan was not filed. The flight was originating at the time of the accident. The pilot reported that his glider, the trail glider, and another glider, the lead glider, were being towed simultaneously by a single tow plane. The lead glider was attached with a 200-foot rope, while his glider was attached to a 300-foot rope. The trail pilot stated that after taking off the lead glider started to descend back to the runway; the lead pilot had elected to release from the tow plane due to a "slack-line" condition. The trail pilot reported that after realizing that his tow rope was under the lead glider's right wing, and that his glider and the tow plane were ascending, released his tow rope. The trail pilot stated that he feared that his tow rope would pull the lead glider's right wing up causing him to ground loop if he did not release the tow rope. The trail pilot further stated, "Instinctively, I turned right immediately after releasing from the tow plane, then realized that I did not have enough airspeed or altitude to return to the airport. I tried to level my wings but my right wing tip struck the ground." The glider came to rest upright in a rice field east of the runway and sustained substantial damage to its right wing and empennage. In a statement submitted to the IIC, the lead glider pilot reported that he was connected to a shorter tow rope, while the accident trail glider was attached to a longer tow rope, positioned aft and to the right of his glider. The lead pilot stated that after taking off he encountered a slack line, which prompted him to perform a precautionary release, followed by clearing to the left and landing uneventfully off of the west side of the runway. The lead pilot further stated that after landing he observed the accident glider strike the ground with its right wing tip heading in a southerly direction, about 100 yards east of the departure runway. ## Aircraft - Registration: [N7HV](https://openairdocs.org/aircraft/N7HV), registered now, S/N 265CS, built 2000 (OpenAirDocs) - Reported make and model: SCHEMPP HIRTH DISCUS CS - Registry model: [Schempp-Hirth DISCUS CS](https://openairdocs.org/model/schempp-hirth-discus-cs) (registry code 38019VS) (OpenAirDocs) - Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs) - Category: Glider - Serial number: 26SCS - Airframe hours: 1152 - Damage: Substantial damage - Flight: Glider tow, Part 91 - Operator: Richard M Parker - Registered owner: John G Kahrs - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, May 10, 2009 - Departed: CN12, Williams, CA - Destination: CN12, Williams, CA - Airport: CN12, Williams Gliderport, runway 34, 2,500 × 40 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 55; injuries: serious; private; last flight review April 6, 2008; seat: single; flight hours: 1,699 total, 1,072 in this make and model, 1,699 as pilot in command, 194 in the last 90 days, 77 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 200° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 79 °F, dew point 54 °F - Altimeter: 29.94 inHg - Observed at: MYV, 33 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 20090802014629A](https://openairdocs.org/incident/20090802014629A), Aug 2, 2009: Schemp DISCUSCS, Williams, CA, Substantial damage. (-23) Glider released from tow plane at low altitude. Aircraft made a right turn, caught the right wing and cart wheeled into a rice field adjacent to the… ## Docket (2 files) The files NTSB released with the investigation on October 14, 2009, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=74437. 996 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 963 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40319455&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Witness Statement (item 2, .PDF, 33 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40319456&FileExtension=.PDF&FileName=Witness%20Statement-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.