Reading a recent article about premature termination of an aero-tow reminded me of a downwind landing I performed more than 15 years ago at Lachen-Speyerdorf, Germany. That day we had very strong SW winds that created a local wave. We departed in a ASK-21 on aero tow on runway 30 to release in the rotor. There were plenty of clouds from a cold front that had just passed and the grass runway was still soaking wet from the last showers. The wave window had nicely formed with a 5 mile wide window of blue sky in the lee of the mountains. On tow we climbed out slowly against the strong headwind in very turbulent cold air. The light was bright and the contrast from the cloud shadow just to the side of us made for a spectacular view. Andreas and I were flying together in the club’s ASK-21, trying to reach the rotor and then climbing into the wave. We released 5 miles away from our take-off destination at 2500ft AGL. The vario was dancing violently but we soon managed to circle in strong turbulent lift of 5 kts (2.5m/s). This produced a big smile on our faces, and we were already thinking about the best strategy how to jump into the wave from here. We didn’t even finish our thought before our 5kts lift turned into 8kts sink. I tried to stay calm and search for the lost rotor upwind. Accelerating the glider in sink is a daunting task. The needle of the altimeter moves at the same speed as the airspeed indicator increases. We were falling out of the sky. After one or two search S into the wind it was clear that we had lost the rotor and probably our chance to fly in wave for the day. We switched gear into “getting home” mode and pointed the nose towards the airport. With 45kts tailwind I wasn’t too concerned to reach the airfield. The terrain right below us was unladable with vineyards, but farmers fields would start half way home. The trouble was there was water everywhere. The sink was brutal. We were beaten down from the lee with 10 kts sink. The ASK-21 isn’t a particularly fast glider either. With a strong tailwind we weren’t supposed to fly super fast either. But the strong sink dictated fairly high speeds anyway. So we pressed on. Andreas was very quiet in the back. I told him that we could turn into the wind any time now and land on any of the wet fields below us, if the sink continued. I called on the radio for a straight in on runway 12 – well aware of the 25 kts tailwind on the ground. Our runway is 1000m long and I figured that would be enough if I touched down early enough. Going all the way for a pattern to 30 wasn’t an option any more. I kept my field landing option until the last mile and then committed to a straight in for 12. How fast are you supposed to fly your approach in this turbulent air? I opted for 130km/h because of the tree we had to overfly with the wind from behind. We made the tree, full flaps, made the runway and flew, flew, coasted coasted, floated, floated and floated, eating away runway at an alarming speed. We finally touched down shortly after the half mark of the runway, where I used full brakes. That’s when I learned about my biggest oversight. The runway was wet and friction for braking power from the main wheel wasn’t available. We skidded down the runway with 80km/h, 300m to go. Shortly after I lost all roll control from the ailerons because of the tail wind. The right wing dropped at around 40km/h ground speed and we were still skidding despite pumping the brake. Thanks to the wet ground the glider never ground looped and we luckily overran the end of the runway by a mere 50m. There weren’t any obstacles in the path. Then it was quiet. I was shaking. My heart was pumping. Our camarades came running towards us and a quick look at the glider confirmed that nothing had happened to the sailplane. I was very shaken and will never forget about the downwind landing wind speed limits and loss of traction on a wet grass runway.