Helicopter
Air Traffic Control Fully Certified
Human-Machine Interface; Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic
ATC Equipment / Nav Facility / Buildings; Aircraft; Airport; Company Policy; Procedure
Aircraft X was upwind in the traffic pattern. Aircraft Y was in the pattern following Aircraft X. I was working Local Control. I anticipated Aircraft Y was turning in sooner than the typical pattern so I told Aircraft X to start his go around for Aircraft Y in trail of him. Aircraft X started his go around and was at approximately 80 feet on the upwind offset left of the runway when the Airport Surface Detection Equipment (ASDE-X) alarmed. The ASDE-X didn't alarm until Aircraft Y had already touched down. Also when the ASDE-X alarmed it said runway occupied instead of runway go around. I did not issue the Go around instructions to Aircraft Y because he had already landed and was following thru on his touch and go. The ASDE-X alarmed when Aircraft Y was between taxiways which was much too late for reasonable go around instructions to be issued. The ASDE-X is a constant problem and go around instructions should not be required due the inaccuracy of the system.
A Tower Controller reported allowing an aircraft to land even though the Airport Surface Detection Equipment (ASDE-X) alarmed for preceding go-around traffic.