# NTSB GAA19CA506: Grob G103, N901BG, San Antonio, TX, August 22, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: August 22, 2019, 15:45 local (20:45 UTC) - Place: San Antonio, TX - Coordinates: 29.723333, -98.694442 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=29.7233&lon=-98.6944&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: No injuries - Injuries: 1 uninjured - Status: Completed, report March 17, 2020 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA - NTSB case key (mKey): 100129 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA19CA506 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/100129/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=100129 - Page: https://openairdocs.org/ntsb/GAA19CA506 ## Probable cause The failure of the glider tow rope, which lodged in the glider's rudder and resulted in a hard landing. Contributing to the accident was the pilot's failure to properly secure the glider's aft canopy. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Fuselage: aerial tow equipment section](https://openairdocs.org/ntsb-findings/01035301): Aircraft › Aircraft structures · Failure (probable cause); cases with it: [Burkhart Grob G 103 TWIN II, 1 case](https://openairdocs.org/ntsb-findings/01035301/cases.md?model=1660203), [All aircraft, 7 cases](https://openairdocs.org/ntsb-findings/01035301/cases.md) - [Equipment/furnishings](https://openairdocs.org/ntsb-findings/01022500): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Burkhart Grob G 103 TWIN II, 1 case](https://openairdocs.org/ntsb-findings/01022500/cases.md?model=1660203), [All aircraft, 12 cases](https://openairdocs.org/ntsb-findings/01022500/cases.md) - [Use of equip/info: use of equip/system](https://openairdocs.org/ntsb-findings/02063015): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Burkhart Grob G 103 TWIN II, 1 case](https://openairdocs.org/ntsb-findings/02063015/cases.md?model=1660203), [All aircraft, 1,391 cases](https://openairdocs.org/ntsb-findings/02063015/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: [Burkhart Grob G 103 TWIN II, 2 cases](https://openairdocs.org/ntsb-events/510/sequence.md?model=1660203), [All aircraft, 45 cases](https://openairdocs.org/ntsb-events/510/sequence.md) - [Initial climb: Loss of control in flight](https://openairdocs.org/ntsb-events/240); cases with it: [Burkhart Grob G 103 TWIN II, 2 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=1660203), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Initial climb: Altitude deviation](https://openairdocs.org/ntsb-events/282); cases with it: [Burkhart Grob G 103 TWIN II, 1 case](https://openairdocs.org/ntsb-events/282/sequence.md?model=1660203), [All aircraft, 104 cases](https://openairdocs.org/ntsb-events/282/sequence.md) - [Landing: Hard landing](https://openairdocs.org/ntsb-events/092); cases with it: [Burkhart Grob G 103 TWIN II, 1 case](https://openairdocs.org/ntsb-events/092/sequence.md?model=1660203), [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) ## Analysis The glider pilot reported that, while being towed and approaching 3,000 ft above ground level, the glider's rear canopy opened. The glider pilot informed the tow airplane pilot via radio that the canopy had opened, and the tow airplane pilot informed the glider pilot that he would try to tow the glider closer to the runway. Shortly after, the glider entered an uncontrollable downward spin, and the front canopy shattered. The pilot regained control of the glider, and the rear canopy separated from the glider. The glider pilot made an extended right base and prepared for an off-airport landing. The flight controls were not responding properly, and the glider landed hard on the runway. The pilot reported that, after the accident, he found a section of the tow rope still connected to the glider and lodged in the rudder mechanism. A review of photographs of the airplane revealed that the tow rope exhibited overload signatures. Each airplane still had a portion of the tow rope attached to it after the tow rope failed. The glider sustained substantial damage to the composite fuselage. ## Factual narrative The glider pilot reported that, while in tow and approaching 3,000ft AGL, the rear canopy opened. The glider pilot informed the tow airplane via radio of the open canopy, and the tow pilot informed the glider that he would try to tow the glider closer to the runway. Moments later, the glider entered an "uncontrollable downward spin," and the front canopy shattered. The pilot regained control of the glider, and he recalled that the rear canopy had separated from the glider. He made an extended right base and prepared for an off-airport landing. He reported that the flight controls were not responding properly, and the glider landed hard on the runway. The pilot reported that after the accident he, found a section of the tow rope still connected to the glider, which was wrapped and inserted into the rudder mechanism. Photographs received from FAA Inspectors showed that the tow rope exhibited overload signatures. Each airplane still had a portion of the tow rope attached to aircraft after the tow rope failure. The glider sustained substantial damage to the composite fuselage. ## Aircraft - Registration: [N901BG](https://openairdocs.org/aircraft/N901BG), registered now, S/N 3648, built 1981 (OpenAirDocs) - Reported make and model: Grob G103 (TWIN II) - Registry model: [Burkhart Grob G 103 TWIN II](https://openairdocs.org/model/burkhart-grob-g-103-twin-ii) (registry code 1660203) (OpenAirDocs) - Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs) - Category: Glider - Serial number: 3648 - Year built: 1981 - Damage: Substantial damage - Flight: Glider tow, Part 91 - Operator: San Antonio Soaring Society Inc - Registered owner: San Antonio Soaring Society Inc - Airworthiness certificate: Standard, Normal - Departed: 5C1, San Antonio, TX - Destination: 5C1, San Antonio, TX - Airport: 5C1, Boerne Stage Field, runway 17, 5,006 × 60 ft - Equipment: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 68; injuries: none; private; airplane ratings: single-engine land; medical: unknown; flight hours: 0 total, 0 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 4 knots - Visibility: 10 statute miles - Temperature: 91 °F, dew point 64 °F - Altimeter: 29.92 inHg - Observed at: KSAT, 15 nm away ## Docket (3 files) The files NTSB released with the investigation on January 23, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=100129. - Pilot's Statement (item 1, .PDF, 189 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40480200&FileExtension=.PDF&FileName=Pilot%27s%20Statement-Master.PDF - Memorandum for Record – Pilot (item 2, .PDF): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40480201&FileExtension=.PDF&FileName=Memorandum%20for%20Record%20%E2%80%93%20Pilot-Master.PDF - Photo (item 3, .PDF, 167 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40480202&FileExtension=.PDF&FileName=Photo-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.