AN MLG ACR CREW LANDED WITHOUT CLRNC. THEY FORGOT TO SWITCH OVER TO TWR FROM APCH CTL.

Narrative

THE FO WAS FLYING THE ACFT AND THE CAPT WAS HANDLING COMS AND CHKLIST ACCOMPLISHMENT. THE FLT RECEIVED A MODERATE AMOUNT OF RADAR VECTORING TO BE SEQUENCED FOR A VISUAL APCH TO THE L OF 2 PARALLEL RWYS. AS WE RPTED CONVERGING TFC FROM THE R (BEING VECTORED TO JOIN FINAL FOR THE R PARALLEL RWY IN SIGHT; WE RECEIVED OUR FINAL INTERCEPT HDG; CLRNC FOR THE VISUAL APCH AND INSTRUCTIONS TO CONTACT TWR OVER THE MARKER. WE COMPLETED OUR VISUAL APCH AND LNDG UNEVENTFULLY AND; AFTER TURNING OFF THE RWY; NOTICED THAT RADIO WAS STILL ON APCH FREQ. ESSENTIALLY; WE HAD LANDED WITHOUT RECEIVING OR ACKNOWLEDGING SUCH CLRNC FROM THE TWR. A CONTRIBUTING FACTOR TO THIS INCIDENT IS BELIEVED TO BE 2 SEPARATE TCASII ALERTS; ONE WHILE NEARING THE INTERCEPT TO THE LOC; AND A SECOND (WITH RA) ESTABLISHED ON FINAL AND APCHING THE OM. BOTH WERE VALID WARNINGS CONSIDERING THE PROX OF THE TFC (TO OUR R AND SLIGHTLY BEHIND) FOR THE PARALLEL RWY; BUT NONETHELESS WERE DISTRACTING AT THE TIME WHEN A FREQ CHANGEOVER AND RADIO CALL WERE REQUESTED. BOTH PLTS QUICKLY AGREED TO DISARM THE ALERTING FEATURE TO ELIMINATE THE DISTR. I GUESS I JUST WASN'T UP TO THE TANK AT HAND AND FORGOT THE CHANGEOVER CALL.