UNAUTH LNDG LNDG WITHOUT CLRNC.

Narrative

WE WERE ON A CLOSE L BASE FOR RWY 17L AT DFW. APCH CTL ADVISED US TO LOOK FOR AND FOLLOW AN MD-80 TO RWY 17L. WE SIGHTED THE MD-80 AND THE CTLR CLRED US FOR A VISUAL APCH. WE WERE BUSY CONFIGURING THE ACFT FOR LNDG AND MAINTAINING VISUAL SEPARATION ON THE MD-80. THE CTLR WAS BUSY AND NEVER HANDED US OFF TO TWR FREQ. NEITHER OF US NOTICED THIS 'NON HDOF' FROM ATC. WE CLRED THE RWY AT THE HIGH SPD. I LOOKED AT THE RADIO AND SAW WE WERE STILL ON APCH FREQ. I CHANGED TO TWR AND THE CTLR WAS CALLING US. HE ASKED US WHERE WE HAD BEEN AND I SAID I THOUGHT WE HAD HIT THE RADIO BUTTON AND BEEN ON THE WRONG FREQ. AT THE TIME; I THOUGHT WE ACTUALLY HAD BEEN HANDED OFF TO TWR AND THAT I HAD FORGOTTEN TO SWITCH OVER. LATER WE REALIZED WE HAD SIMPLY NEVER BEEN HANDED OFF TO TWR. THE TWR CTLR CLRED US TO CROSS RWY 17R AND CONTACT GND CTL. THE CAPT AND I FELT THE REASON WE DID NOT CATCH THIS ERROR IS BECAUSE WE HAD BEEN ON A CONTINUOUS DUTY OVERNIGHT AND HAD SLEPT MAYBE 4 HRS. WE WERE NOT AS ALERT AS WE WOULD HAVE BEEN HAD WE SLEPT ALL NIGHT. I FEEL REDUCED REST AND CONTINUOUS DUTY OVERNIGHTS SHOULD BE ELIMINATED TO PREVENT THESE TYPES OF EVENTS.