A rail flaw detector is configured for locating flaws in rails of a railroad track and for use with a vehicle travelling on the railroad track. The detector includes at least one signal applicator configured for applying ultrasonic signals to the rail and for receiving return signals; a mechanical subsystem connected to the applicator and to the vehicle and configured for maintaining the at least one signal applicator in operational position on the track. A human-machine interface is connected to the at least one signal applicator, is configured to control the detector and to monitor sensed rail condition. In one embodiment, the human-machine interface includes a schematic display of the rail being monitored and at least one touch screen control for controlling the mechanical subsystem and the at least one signal applicator.