GA SMA UNAUTHORIZED PENETRATION OF ADS ATA.

Narrative

WHILE CONDUCTING A VFR TRAINING FLT THE FOLLOWING SITUATION AROSE. AFTER DEPARTING ADDISON ARPT; WE FLEW TO AIR PARK ARPT; AN UNCTLED FIELD 3 NM N OF ADDISON ARPT. THIS ARPT IS INSIDE THE ADDISON ATA. WE CONVEYED OUR INTENTIONS TO THE ADDISON CTLR AND HE TOLD US TO SWITCH FREQS TO THE AIR PARK CTAF. WE MADE SEVERAL LNDGS AT AIR PARK AND; AT DUSK; DECIDED TO DEPART AIR PARK; EBOUND. FLYING E FROM AIR PARK; WE WERE MONITORING THE ADDISON TWR FREQ. THE TWR BEGAN MAKING CALLS TO THE UNIDENTED ACFT NE OF ADDISON. WE BELIEVED THAT SINCE WE WERE DEPARTING AN UNCTLED FIELD WITHIN ANOTHER ARPT'S ATA; CONTACT WITH THE PRIMARY ARPT WAS NOT NECESSARY. WE HAD NOT; THEREFORE; PLANNED TO COM WITH ADDISON TWR. LOOKING N; WE SAW ANOTHER ACFT AND BELIEVED THE TWR'S XMISSION WAS INTENDED FOR IT. WE NEVER HEARD ANY REPLIES TO THE TWR'S BROADCASTS TO THE UNIDENTED ACFT NE OF ADDISON. LOOKING BACK; I BELIEVE I SHOULD HAVE ACKNOWLEDGED THE CALL; BUT AT THE TIME; I DIDN'T BELIEVE IT WAS NECESSARY. WE NEVER OBSERVED ANY UNUSUAL SITUATIONS AND COMPLETED THE FLT WITHOUT ANYTHING ELSE OUT OF THE ORDINARY OCCURRING. THIS WAS A CONFUSING SITUATION WHERE WE WERE IN THE ATA ONLY BRIEFLY AND WERE NOT REQUIRED TO MONITOR THE TWR FREQ.