GA SMA UNAUTH LNDG DURING A TRAINING FLT.

Narrative

I WAS PIC ON THIS TRNING FLT IN THE STUDENT'S OWN ACFT. WE DEPARTED HPN; AND BECAUSE HPN WAS VERY BUSY DECIDED TO FLY TO STEWART TO DO A SERIES OF LNDGS THERE. AFTER HAVING ASKED FOR A FREQ CHANGE FROM HPN TWR; WE CONTACTED NY APCH (126.4) AND WERE ASSIGNED A DISCRETE SQUAWK CODE. WE RECEIVED ADVISORIES UNTIL APPROX 10 MI S OF STEWART WHERE WE WERE ADVISED THAT RADAR SVC WAS TERMINATED. WE THEN CONTACTED STEWART TWR ON 121.0. I UNDERSTOOD THAT WE WERE CLRED FOR A STRAIGHT IN LNDG ON RWY 34. WE ACKNOWLEDGED AND PROCEEDED TO CONTINUE THE APCH TO RWY 34; AND WE LANDED UNEVENTFULLY; COMING TO A FULL STOP BEFORE XING RWY 9-27. TWR DID NOT INITIATE A XMISSION AND I THEN CALLED TWR; ASKING IF WE COULD TAXI FOR A TKOF. TWR RESPONDED THAT WE HAD NOT BEEN CLRED TO LAND AND INSTEAD WERE ASKED TO RPT ON 3 MI FINAL. I APOLOGIZED; TWR THEN HAD US TAXI TO THE BEGINNING OF RWY 16; WHERE WE DID A 360 DEG TURN; AND WERE SUBSEQUENTLY CLRED FOR TKOF. CONTRIBUTING FACTORS: THE PLANE WE USED IS VERY NOISY AND THE XMISSION WAS NOT UNDERSTOOD AT ALL. I DID THINK THAT WE WERE CLRED TO LAND. HOW THIS COULD HAVE BEEN AVOIDED: USE EARPHONES; WHICH WE WILL DO FROM NOW ON. ALSO; THE TWR CTLR MUST HAVE SEEN US FOR AT LEAST 3 MI OUT ON A STRAIGHT IN APCH THAT HE TOLD US TO DO. HE COULD HAVE EASILY STOPPED US FROM LNDG BY MAKING JUST 1 CALL TO US.