- Date
- August 22, 2019, 15:45 local (20:45 UTC)
- Place
- San Antonio, TX
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Initial climb
- Aircraft
- N901BGGrob G103
- Defining event
- Initial climb: Glider tow event
- Weather
- Visual (VMC) · Day
- Status
- Completed · report March 17, 2020
- Report
- Approved by Office Director
- NTSB office
- General Aviation Accidents
- Parties
- FAA
- Case key
- 100129
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
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 · 3
NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.
Sequence of events
The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.
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
- Reported as
- Grob G103 (TWIN II)
- Category
- Glider
- Serial number
- 3648
- 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
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 68
- Injuries
- None
- Certificate
- 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
The files NTSB released with the investigation on January 23, 2020, on NTSB’s docket system: statements, records, photos and specialists’ reports.