RWY INCURSION BY AN SA227 CARGO PLT WITH A C172 ON FINAL AT CYYC; AB.

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I OPERATED A PART 135 CARGO FLT FROM SEA TO CYYC. I LANDED ON RWY 16 AND TURNED R AND EXITED ONTO TXWY A3. I WAS INSTRUCTED TO CONTACT GND ON A NEW FREQ OF 124.95. I CONTACTED THEM AND ADVISED THEM THAT I WANTED TO TAXI TO CUSTOMS; WHICH WAS STRAIGHT AHEAD ON TXWY A JUST S OF RWY 25. I WAS INSTRUCTED TO TAXI S ON TXWY A AND HOLD SHORT OF RWY 25. I DON'T REMEMBER IF I READ BACK THE HOLD SHORT INSTRUCTION OR NOT. BUT IT DID NOT STICK IN MY MIND. I STARTED TAXIING AND ASKED GND IF 124.95 IS THE NEW FREQ. THEY SAID IT WASN'T; THERE WAS A STUCK MIKE ON 121.9. APCHING RWY 25 I WASN'T REALLY SURE WHETHER I WAS CLRED TO CROSS IT. I SAW A CESSNA 172 ON SHORT FINAL FOR RWY 25. HOWEVER I RECALLED A C172 BEING CLRED TO LAND ON RWY 25 AND TO HOLD SHORT OF RWY 16 AS I WAS ABOUT TO LAND ON RWY 16. TXWY A IS W OF RWY 16 SO SINCE THERE WAS NO CONFLICT I ASSUMED I WAS CLRED TO CROSS RWY 25. I THEN TAXIED ACROSS RWY 25. 3 ITEMS PLAYED A FACTOR IN THIS INCURSION. FIRST OF ALL I WAS DISTRACTED BY THE DIFFERENT GND FREQ AND THEN I DISTRACTED MYSELF MORE BY ASKING GND. SECOND; I RECALLED THAT THE C172 WAS CLRED TO LAND ON RWY 25 AND HOLD SHORT OF RWY 16. AND FINALLY THIRD; THE LAST FEW TIMES I FLEW INTO CALGARY I EXITED ON A3 AND HAD BEEN INSTRUCTED TO TAXI ON TXWY A TO CUSTOMS AND CROSS RWY 25. THE INCIDENT WOULD PROBABLY NOT HAVE HAPPENED IF I HAD NOT BEEN DISTRACTED BY THE DIFFERENT GND FREQ. IT WOULD PROBABLY ALSO NOT HAVE HAPPENED IF I HAD NOT BEEN TO CALGARY BEFORE OR HAD NOT GOTTEN THE SAME TAXI INSTRUCTIONS SEVERAL TIMES IN A ROW. IT WOULD DEFINITELY NOT HAVE HAPPENED IF I HAD NOT REMEMBERED THE CESSNA BEING CLRED TO LAND ON RWY 25 AND HOLD SHORT OF RWY 16. I WOULD HAVE SEEN THE CESSNA ON SHORT FINAL FOR RWY 25 AND WOULD HAVE HELD SHORT UNTIL GND WOULD HAVE INSTRUCTED ME TO CROSS. THE ONLY SURE WAY I THINK OF TO PREVENT INCURSIONS LIKE THIS ONE IS TO VERIFY A XING CLRNC WHEN REACHING A HOLD SHORT LINE EVERY TIME IF THERE IS EVEN ONE OUNCE OF UNCERTAINTY.