GA SMA UNAUTH PENETRATION OF AIRSPACE MIA TCA. PLT COMPLAINT ABOUT CONFUSING SET OF ARCS; RADIALS; AND DISTANCES THAT ARE USED TO IDENTIFY THE MIA TCA.

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PLT ADVISED BY FT MEYERS APCH TO CALL AREA SUPVR; MIAMI TRACON. SUPVR CLAIMS ACFT MADE UNAUTHORIZED PENETRATION OF MIAMI TCA WHILE ON WBOUND DEP FROM TAMIAMI ARPT. SUBJECT ACFT AND PLT WERE DEPARTING TMB AT ABOUT TIME SUPVR CLAIMS PENETRATION OCCURRED. HOWEVER; WE HAVE NO EVIDENCE THAT SUPPORTS CTLR'S CLAIM THAT THIS ACFT PENETRATED THE TCA. A STUDY OF THE MIAMI TCA CHART REVEALS; HOWEVER; HOW WE; OR ANYONE ELSE; COULD EASILY HAVE PENETRATED THE TCA BY ACCIDENT. THE MIAMI TCA IS MADE UP OF A CONFUSING SET OF ARCS; RADIALS AND DISTANCES FROM 3 DIFFERENT POINTS: MIAMI ARPT; MIAMI VOR AND BISCAYNE VOR. IN MOST CASES; TO FIX A BOUNDARY OF THE TCA ONE NEEDS TO KNOW DISTANCE OR BEARING FROM 2 OF THESE REFERENCE POINTS. ONE OF THEM; THE MIAMI ARPT; HAS NO NAVAID SIGNAL TO PROVIDE BEARING OR DISTANCE. IN THE CASE OF OUR ACFT DEPARTING TMB; WE GOT OUR VOR ON THE BSY 270 DEG RADIAL AND PLANNED TO FLY SOUTH OF THE BSY 270 DEG UNTIL 20 MI FROM MIA; THEN TURN NW TO FT MEYERS. IT IS POSSIBLE THAT WE USED THE BSY DME FOR THE 20 MI FIX AND TURNED NW BEFORE WE WERE ACTUALLY 20 MI FROM KMIA. TCA'S SHOULD BE BASED ON RADIAL AND DME INFO FROM ONE NAVAID LOCATED IN THE CENTER OF THE TCA.