Details of Report

I observed one of your airplanes nearly run off the end of runway 11 at CAT4 airport. Aircraft came in overhead CAT4 airport to join a right-hand downwind for Rwy 11. He did an overshoot, I assume because he was too high but I wasn't paying much attention at that point yet. I noticed quite abrupt power changes after the overshoot and in the circuit. Then the second try he came in high and fast, he did a slip on final but ended up high over Rwy 11 and floated well past taxi way Charlie (there's a good down-slope in the runway after that point) before touching down on the runway. Subsequently I heard and saw the airplane go into full brakes and skid left and right over the runway to make a stop just before the end of Rwy 11. I noticed a KD Air Navajo was landing on Rwy 29 about 1 or 2 minutes after. . .