A80 PRM-Monitor Controller described a directed missed approach event when the aircraft failed to appear on the PRM display as per requirements; noting aircraft transponder anomalies may have caused the problem.

Narrative

I was working PRM-Monitor A position. Weather IFR; Tower visually acquiring aircraft at 1 mile final. Bases estimated 600 FT AGL. Air Carrier X was coming in toward the final from the Southeast; assigned Runway 28. I wrote him down on my pad; as required by SOP. Traffic was light; and the aircraft joined final at an appropriate spot. I was looking at the ARTS display above my position to locate the next aircraft in the sequence; and then Air Carrier X checked on the Tower frequency; again at an appropriate time and place. I looked at the PRM scope and the target was NOT displayed on the PRM scope. It took me a few seconds to piece everything together; and I called the Approach Supervisor over to show him what was going on. Air Carrier X had joined the final; and was tracking well on the ARTS; appeared to be centered on the localizer; however local procedures require a PRM Monitor with simultaneous arrivals to 27L and 28. There was an aircraft on the 27L final; and I'm not sure if he was appropriately staggered ahead and to the right of Air Carrier X. After conferring with the supervisor; I pulled Air Carrier X off the approach; and asked him if he had any issues with his transponder. It sounded as if he said he had no issues. He was re-sequenced to the airport without incident. Maintenance is going to send the data to their PRM group for analysis. I had ATL Tower ask Air Carrier X to call the TRACON to see if he had any anomalies in the cockpit. It turned out he did have issues; and may very well have told me that the first time; I had a couple people around me talking about the situation when I pulled him off the first time. One of his transponders had a maintenance write up on it; and I guess the second transponder hadn't been working correctly. The aircraft acquired on the second approach attempt; but the aircraft was 'Conflict Alert' (CA) with itself all the way down the final. The PRM track was not as 'solid' as the tracks on other finals; occasionally going into CST; no altitude readout; and occasionally 'jumping around'. Track never approached the NTZ during second attempt.