K13 Glider Launch Failure/Cable Break – 300ft Thermal – GoPro Cockpit View – (glider emergency)The start of the takeoff run was so smooth I said “whoohoo”, and I established the 45 degree climb in the slowest rate possible. By the time I established in my full climb, *BANG*, the cable’s gone. It was one second of fear, followed by mechanical thinking and mechanical actions: lowering the nose, establishing a good speed, releasing the cable, checking for 55+ and turning downwind after seeing I can not land ahead without crashing into the winch. What followed was an abbreviated circuit and a landing on the takeoff runway, exactly the way I briefed myself in the “Eventualities” part of the CBSIFTCBE checks. Watching the video, I can see that my airspeed increased before the launch failure, but I did not wave off as I was below 500ft, and the moment before it the airspeed reached more than 80 knots in a single second. Suspecting a strong thermal entry during launch, instantly lifting me up and snapping the strop. I can confirm that, as the pilot who flew before me hit a thermal at the top of the launch, so it was very likely that the wind moved the thermal further into the runway.