Large Transport
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 25.8
Confusion; Communication Breakdown
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Separated Traffic
Human Factors; Procedure; Airspace Structure
Was working R20 position with a D-side in place.  From what I remember (and what OM told me later) that Aircraft X checked on the frequency stating he had a clearance 'to cross abeam OSOGY at FL240.'  Aircraft Y was climbing to FL230 off PBI airport converging with Aircraft X.  I called traffic to each.  I then noticed that Aircraft X was descending below his assigned altitude.  I observed his Mode C at FL234.  I told Aircraft X to maintain FL230 which he immediately read back.  Then I went back to Aircraft Y and issued 'Aircraft Y maintain FL220 immediately.'  He read it back promptly also.  Both aircraft leveled at the newly assigned altitudes.  No separation was lost. Aircraft Y reported that the RA was being given at the same time I leveled off the aircraft at FL220.I think the point of OSOGY should be moved a few miles south or north of where it is to de-conflict with the common BLUFI departures.  Too many times both aircraft are leveling or about to level and there are many RAs even after calling traffic to both planes.
Aircraft X checked in on frequency with a pilot discretion descent to cross abeam the OSOGY Intersection at FL240.  The Radar Controller issued traffic to Aircraft X climbing to FL230.  The pilot acknowledged the traffic call; and reported the aircraft in sight.  Aircraft X descended below the assigned altitude and the Radar Controller cleared the aircraft to maintain FL230.  Immediately the Radar Controller assigned Aircraft Y; to maintain FL220.  Both aircraft reported level at FL230 and FL220. I did not see a loss of separation.Several minutes later Aircraft Y advised he did experience a TCAS RA.  Also; Aircraft X advised he was issued a descent clearance to 160; from the previous Controller.  I closed the sector position and reported the incident to the Operations Manager on duty.  The departure routes from PBI to join the AR routes are in a direct flight path to converge with inbound arrival routes landing MIA. The departures are climbed to FL230 and the arrivals are descended to FL240.  There have been previous incidents in this airspace location where TCAS alerts have occurred.  The workload on the controllers to issue traffic in this area is demanding and continuous.  Really; I mean non-stop traffic calls; 24/7.I recommend different departure routes and/or different arrival routes.  Also; the present airspace configuration does not allow for profile climbs or descents.  I do not think we provide a good service to these aircraft by purposely converging aircraft 1;000 feet apart.  I think these operational procedures are a safety risk in the NAS which should be identified and mitigated.I believe this incident will repeat; or this is a duplicate of previous reports.
Two ZMA controllers describe a near loss of separation.