Sunday, March 08, 2020

Glider Tow Event: Grob G103 Twin II, N901BG; accident occurred August 22, 2019 at Boerne Stage Field Airport (5C1), Kendall County, Texas

View of damage to the canopy. 
Federal Aviation Administration 

 View of damage to the composite structure of the lower fuselage. 
Federal Aviation Administration 

Additional Participating Entity:

Federal Aviation Administration / Flight Standards District Office; San Antonio, Texas

Aviation Accident Factual Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board:

Location: San Antonio, TX
Accident Number: GAA19CA506
Date & Time: 08/22/2019, 1545 CDT
Registration: N901BG
Aircraft: Grob G103
Aircraft Damage: Substantial
Defining Event: Glider tow event
Injuries: 1 None
Flight Conducted Under: Part 91: General Aviation - Glider Tow 

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. 

Pilot Information

Certificate: Private
Age: 68, Male
Airplane Rating(s): Single-engine Land
Seat Occupied:
Other Aircraft Rating(s): None
Restraint Used:
Instrument Rating(s): None
Second Pilot Present: No
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Unknown
Last FAA Medical Exam:
Occupational Pilot: No
Last Flight Review or Equivalent:
Flight Time: 

Aircraft and Owner/Operator Information

Aircraft Make: Grob
Registration: N901BG
Model/Series: G103 TWIN II
Aircraft Category: Glider
Year of Manufacture: 1981
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: 3648
Landing Gear Type: Retractable - Tricycle
Seats: 1
Date/Type of Last Inspection:
Certified Max Gross Wt.:
Time Since Last Inspection:
Airframe Total Time:
Engine Manufacturer:
Engine Model/Series:
Registered Owner: San Antonio Soaring Society Inc
Rated Power:
Operator: San Antonio Soaring Society Inc
Operating Certificate(s) Held: None 

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: KSAT, 789 ft msl
Distance from Accident Site: 15 Nautical Miles
Observation Time: 2035 UTC
Direction from Accident Site: 134°
Lowest Cloud Condition: Scattered / 7000 ft agl
Visibility:  10 Miles
Lowest Ceiling:
Visibility (RVR):
Wind Speed/Gusts: 4 knots /
Turbulence Type Forecast/Actual:
Wind Direction: 150°
Turbulence Severity Forecast/Actual:
Altimeter Setting: 29.92 inches Hg
Temperature/Dew Point: 33°C / 18°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: San Antonio, TX (5C1)
Type of Flight Plan Filed: None
Destination: San Antonio, TX (5C1)
Type of Clearance: None
Departure Time:  CDT
Type of Airspace: Class E

Airport Information

Airport: Boerne Stage Field (5C1)
Runway Surface Type: Unknown
Airport Elevation:1383 ft 
Runway Surface Condition: Dry
Runway Used: 17
IFR Approach: None
Runway Length/Width: 5006 ft / 60 ft
VFR Approach/Landing: Full Stop; Traffic Pattern 

Wreckage and Impact Information

Crew Injuries: 1 None
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 None
Latitude, Longitude: 29.723333, -98.694444 (est)

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