COM CFI PLT OF SMA SEL ACFT INADVERTENTLY PENETRATED A TCA.

Narrative

I DEPARTED ILG; FOLLOWED V170 TO SWANN INTXN AND WENT S OF SWANN ABOUT 10 MI NE OF SWANN. THEY GAVE ME 119.7 FREQ AND I WAS GIVEN A SQUAWK CODE AND A CLRNC INTO THE BALTIMORE TCA. I HAD DSNDED FROM 6500 TO 5500 THEN TO 2500 WHEN I TURNED W TO 275 DEG TO GO RNAV DIRECT TO GCS. THE RNAV WAS SET TO 115.1 ON THE #1 NAV AND THE 235 DEG RADIAL AT 16.7 DME. I PROCEEDED JUST N OF ANNAPOLIS TOWARD CGS AND WAS CLRED LOWER TO 1700 FT. BALTIMORE APCH TERMINATED RADAR SVC AT ABOUT 5 MI E OF CGS WHICH IS WHAT THE RNAV WAS SHOWING AS WELL. THE DME WAS SET TO 115.1 AND WAS SHOWING 10-12 MI AND INCREASING. HOWEVER; THE RNAV WAS SHOWING THE BEARING TO THE STATION FROM 275 DEG INITIALLY TO 250 THE 220 ETC. BY THIS TIME THE DME OFF OF 115.1 INDICATED 15-17 MI FROM THE VORTAC. I HAVE BEEN TO CGS ON ONE OTHER OCCASION AND STARTED TO LOOK FOR THE UNIVERSITY OF MARYLAND. HOWEVER; AS I COULD NOT RECOGNIZE ANYTHING I KNEW SOMETHING WAS WRONG BECAUSE THE RNAV HAD ME GOING TOO FAR S AND THE #2 VOR SET ON THE 235 DEG RADIAL OUT OF 115.1 WAS NOT COMING IN. AS I STARTED TO CIRCLE I WAS 18 MI OR SO ON THE DME AND ON THE 220 DEG RADIAL OUT OF BALTIMORE. ALSO; I SPOTTED THE ARENA WITH THE CONCAVE ROOF ABOUT 1 1/2 MI AWAY OR SO. I ALSO SAW A LARGE ARPT S TO SW THAT WAS ANDREWS AFB. IT LOOKED 7 MI AWAY OR SO BUT I WAS CIRCLING AND WAS NOT SURE IF I HAD ENTERED THE TCA OR NOT. AT THIS TIME I REALIZED I WAS NOW WHERE I WANTED TO BE AND TURNED TO A HDG OF 040 OR SO TO LEAVE THE AREA. I USED THE #2 NA ON 235 DEG RADIAL OFF OF 115.1 WITH THE DME TO GET JUST NE OF CGS TURN L AND FINALLY RECOGNIZE THE UNIVERSITY OF MARYLAND AND FIND THE ARPT. I ENTERED THE PATTERN AT CGS AND THE RNAV INDICATED 220 DEG BEARING AT 4 MI; THE #2 NAV AND DME WERE DIRECTLY ON. I BELIEVE I WAS EITHER CLOSE TO OR INSIDE OF THE 7 ADW RING OF THE WASHINGTON TCA BY THE ARENA.