Any Unknown or Unlisted Aircraft Manufacturer
Air Traffic Control Fully Certified
Communication Breakdown; Human-Machine Interface
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Flight Crew Executed Go Around / Missed Approach
Human Factors; Procedure
The aircraft was a business jet. I was working Local North; Local Center; and had also picked up Local South approximately 10 minutes into this session. Traffic was not busy. I noticed the aircraft on final for Runway 27 and walked to where I could get a complete visual scan of that runway (I was working from the Local Center position.) I had been working several aircraft to these two runways but the business jet may have been the first aircraft I had for Runway 27 since I had picked up the position. I reached out to contact the aircraft without success. I then heard a partial call over the Guard frequency that sounded like either all or part of the call sign was used. I had reached out to the aircraft more than once as I had not noticed the pilot check in. I heard the Guard frequency when the aircraft was inside the final approach fix. I grabbed a light gun and notified the Supervisor and Local West about a possible go-around. I at some point called down to the final position to have them try the aircraft again to switch to my frequency. I noticed the aircraft also had entered a second beacon code of 7606. I was assuming the pilot had tried entering 7600 for radio failure. I had notified Local West early on that we were not talking to the aircraft and kept the Local West Controller advised. The Supervisor did issue a landing clearance over the Guard frequency at my request. The aircraft did not respond. I had also handed a light gun to another Supervisor who was in a better position to issue the Cleared to land light signal. The light gun was given probably around a three mile final. During this time I had been trying to navigate on the touch screen that we use for frequencies and communications. I found myself on a page I didn't want and was trying to bring up the guard frequency page; when the Supervisor issued the landing clearance on Guard. I also switched pages when trying to call the final controller. The aircraft did not react to either the Green Light or the Guard call and initiated a go-around. All Local positions had been given a heads up early on and there were not any loss of separation issues. The aircraft then checked on to the Local West frequency during the go-around. At that time I clicked back to my main frequency page and noticed that the Local South frequency was not selected. I figure I must have forgotten to select the frequency when I picked up Local South or I had hit something wrong while navigating the touch screen. I am thinking it is highly likely that I never had it selected. Either way the Local West Controller vectored the aircraft and cleared the aircraft to land. I may have forgotten to select the frequency. Recommendation; briefings that something be verbally stated about the frequencies being selected when combining positions; other information on the check lists. Pilots should be reminded to be looking for light gun signals in situations involving communication issues. Pilots should also be monitoring guard frequencies.
Tower Controller described a go around event when communication with an arrival was not established. The reporter later realized the appropriate frequencies were not selected after positions were combined.