The pilot was approaching to land on runway 23 with a tower reported wind from 170 degrees at 10 knots. He reported that at 20 feet, and an airspeed of 100-110 mph, the airplane fell to the runway. The airport was equipped with a low level windshear detection system. According to data from 2 minutes before the accident to 2 minutes after the accident, from the on-airport sensors, the wind was variable by 40 degrees, and the velocity changed by about 5 knots.