Accident Grob G103 Twin Astir ZS-GPD, Saturday 18 November 2023
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Date:Saturday 18 November 2023
Time:12:30 UTC
Type:Silhouette image of generic gr13 model; specific model in this crash may look slightly different    
Grob G103 Twin Astir
Registration: ZS-GPD
MSN: 3010
Total airframe hrs:671 hours
Fatalities:Fatalities: 0 / Occupants:
Other fatalities:0
Aircraft damage: Substantial
Location:near Brits Airfield -   South Africa
Phase: Initial climb
Departure airport:Brits (FABS)
Destination airport:Brits (FABS)
Investigating agency: CAA S.A.
Confidence Rating: Accident investigation report completed and information captured
An instructor and a student pilot on-board a Twin Astir Glider with registration ZS-GPD were on a training flight from Brits Airfield (FABS) with the intention to return to the same airfield when the accident occurred. The training flight was
conducted under visual meteorological conditions (VMC) by day.
The instructor pilot stated that the tug aircraft with the glider in tow lined up on Runway 20 in preparation for the flight. A few minutes later, the tug aircraft and the glider took off. During the climb at approximately 150 feet (ft) above ground level (AGL), the tug aircraft rapidly lost height due to the downdraft which resulted in the misalignment of the glider and the tug aircraft. According to the Pilot's Operating Handbook (POH) the normal height for the tug aircraft to release the glider is 450 (ft). After the glider crew realised that the tug aircraft is not gaining sufficient height, they initiated a left turn to return to the take-off runway. As a safety precaution, the instructor pilot (glider) called for the release of the glider from the tug aircraft so that he can execute a forced landing on a field due to the absence of lift/thermals. During the forced landing, the undercarriage collapsed, and the tail boom was substantially damaged. Both occupants were not injured.
The tug aircraft returned to the airfield where it landed safely and undamaged.

Probable Cause The instructor pilot disconnected the glider from the tug aircraft at a height of 150 feet AGL due to
the tug aircraft experiencing a downdraft; as a result, the instructor pilot conducted an unsuccessful forced landing on a field.

Contributing Factor
Insufficient thermals to sustain lift.

Accident investigation:
Investigating agency: CAA S.A.
Report number: CA18/2/3/10390
Status: Investigation completed
Duration: 3 months
Download report: Final report




Revision history:

20-Feb-2024 16:55 ASN Added
20-Feb-2024 16:58 ASN Updated [Aircraft type, Phase, Departure airport, Destination airport, Narrative, Plane category]
20-Feb-2024 16:58 ASN Updated [Location]

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