COMMUTER LANDS WITHOUT CLRNC.

Narrative

MY CAPT WAS FLYING; I WAS WORKING THE RADIOS. CEILING WAS LOW AND WE WERE DOING THE BEFORE LNDG CHKLIST AND I WAS LOOKING FOR THE RWY. INSIDE THE MM THE APCH CTLR FORGOT TO HAND US OVER TO TWR FREQ; AND I DIDN'T QUESTION THIS. I DON'T REMEMBER IF APCH CLRED US TO LAND; BUT I KNOW THAT HE DIDN'T HAND US OVER TO TWR. WE LANDED AND PULLED OFF THE RWY AND I REALIZED WE STILL HAD APCH CTL ON OUR RADIO AND HAD NOT PUT TWR FREQ ON THE COM RADIO. I ASKED MY CAPT IF HE REMEMBERED IF WE WERE CLRED TO LAND AND HE SAID HE DIDN'T REMEMBER THEM CLRING US TO LAND; EITHER. WHEN WE SWITCHED TO GND SHE IMMEDIATELY TOLD US TO TAXI TO OUR GATE AND NEVER SAID A WORD ABOUT ANYTHING ELSE. IT MAKES ME WONDER IF APCH AND TWR WAS BEING WORKED BY THE SAME PERSON AND PERHAPS HE DID CLR US AND WE DON'T REMEMBER. TWR ALSO MAY HAVE CLRED US TO LAND; BUT WE DID NOT ACKNOWLEDGE BECAUSE WE WERE NOT ON THAT FREQ. IN THE FUTURE; I WILL ALWAYS QUESTION THE CTLR WHEN INSIDE THE MM IF WE ARE STILL ON APCH CTLR; NO MATTER HOW BUSY I AM.