Date: 201201
Local time of day: 1801-2400
Location: ZMA.ARTCC, FL
Aircraft: EMB ERJ 190/195 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class E ZMA
ATC / advisory: Center ZMA
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Other / Unknown
Anomaly: ATC Issue All Types
Detector: Person Air Traffic Control
Result: General None Reported / Taken
Contributing factors: ATC Equipment / Nav Facility / Buildings
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: An E190 was inbound to FLL with a pilot discretion descent clearance to cross DEKAL at 6;000. Shortly after he passed ZBV; he reported that he had responded to an RA. I told him I did not observe any traffic in his vicinity and I toggled to DARC where I also did not observe any traffic. Approximately 5-7 minutes earlier I observed a target over DEKAL Mode C indicating 6;500 appearing to be headed southeast bound. A minute or two later the target had disappeared. I toggled to DARC and the target was showing up in DARC but when I went back to NAS it was still not showing up. In this area; this type of situation was been reported before but to my knowledge usually once you to go DARC and then back to NAS the target will then be showing in both places. So I quickly went back and forth a few times each time the target would only show up in DARC and not NAS. I kept this in mind knowing I had potential opposite direction traffic approaching DEKAL. A few more minutes went by and the E190 was now about 20 miles southeast of ZBV and so once again I toggled to DARC and this time there was no target at all. I went back and forth a few times and still nothing. I thought that the target I had observed earlier must have either been a phantom target or must have been an aircraft which had descended below radar coverage and/or landed at MYBS. A few minutes later the E190 reported the RA and there was no observed target at all in NAS or DARC. I toggled again a minute later to see if I could see it once they passed and once again there was no target in NAS or DARC. The E190 said that he had not ever had a visual on the aircraft but that the TCAS said it was within 100 FT of his altitude. This is a known problem in this area. It was brought to our attention by a few similar events as what I have just reported. Since then there has been nothing done to fix it. We have just simply been instructed to be aware of it and to periodically check the DARC to see if we are missing any targets. This area is right along a busy inbound corridor presenting a very dangerous situation. It happens probably every single day that we are missing targets and therefore possibly missing important traffic calls. Simply telling us to be aware and occasionally check the DARC is setting everyone involved up for a potential catastrophe. This sector has the tendency to get very saturated and that specific section of airspace is very narrow with little room for maneuvering. And what happened today is even worse because I did what I was instructed to do by checking the DARC and still the target was not there. I don't really know how to logistically 'fix' or 'prevent' this from happening again; I just know that something needs to be done about it before something really bad happens.




Synopsis: ZMA Controller described a unsafe situation involving the absence of target information on either the NAS or DARC equipment; the reporter notes this problem is prevalent in a very busy traffic area and has existed for some time.