A deviation from normal flight procedures and an inoperable collision avoidance system were cited in the Transportation Safety Board’s limited scope investigation of the midair collision of a glider and tow plane in southern Alberta in 2019. A student and instructor on the glider were killed after the Cessna 182 tow plane cut the glider’s tail off with its propeller over the Black Diamond/Cu Nim Airport last July 26. The TSB said in its report the tow plane pilot didn’t see the glider before the collision and its collision avoidance system was not working. It also cited an abnormal flight pattern prior to the collision in its report.

The TSB said gliders normally drop the tow rope in straight and level flight but in this case the glider separated during a turn and the tow pilot was not aware it had released. The glider pilot thanked the tow pilot for the tow over the radio and the tow pilot, after manoeuvring to try to see the glider began preparing to land. That included a clearing turn to the left where it encountered the glider. Without its tail feathers, the glider went into an unrecoverable dive. The tow plane’s prop, cowl and right wing were damaged but the pilot was able to dead stick to a safe landing on the runway. He was not injured.