We were flying up at Dumbe Mountain, Paulpietersburg for a few days. The wind was Northerly, and we all launched off the NE take-off site. The main feature of the launch-site is that the ground slopes downhill for about 100 meters, then flattens out for a short while, and then drops away at a sheer cliff. On the left (North side) there is a small hilly feature which gives off some mechanical turbulence in this wind direction.
I launched, flew forward towards the cliff, and encountered big sink. I then had at least a 60% collapse on the left hand side of my wing. I think it was rotor from the cliff. The glider started turning immediately towards the mountain. My height was now 20 meters above ground level. I caught the assymmetric spiral at 90 degrees by leaning and braking hard to the right. Due to that action I lost another 10 meters and now had only 10 meters left.
I then wanted to pump out the left side, but my glider was parachutal, due to the aggressive counter-steering, which had been necessary to stop me flying into the mountain.
I fell the last 10m and impacted with the ground, hard. I landed on my back.
My airbag absorbed the complete impact. I was not at all injured. I checked my vario, and my descent rate was -7,0 m/second, which is the equivalent of free-falling from a height of 2½ meters.
In conclusion; if I had not counter-steered as aggressively, I would have flown face-first into the mountain. If I had been about 50 meters above the ground the glider would have re-inflated and flown again, but due to only having 10m to play with; I was very grateful for my Airbag.
The worst part of this whole incident was I now had to walk up a steep 55 meters, back to take-off.