The gyroglider was being towed in alternate directions along a strip. There was a 10 knot wind component along the strip direction and the temperature was 34 degrees Celsius. During one downwind towing sequence the wind speed increased. The pilot signalled for a higher towing speed, but as the vehicle driver had been instructed to observe a limit of 80 kph, he did not increase speed further. The gyroglider subsequently landed heavily and overturned. The high density altitude conditions, coupled with the gusting tailwind and aircraft weight approaching the maximum permissible, required a towing airspeed higher than normal. Towing speed was limited by fixed ground speed limits.
