Narrative:

Captain and copilot very fatigued after a long night of flying. Handed over to tower, but forgot to check on to the new frequency. Landed and then called ground control. Ground controller did not seem upset. We assume tower still issued a clearance to land, even though we were not on frequency to hear it.

Google
 

Original NASA ASRS Text

Title: AN ATX FREIGHTER LANDS WITHOUT CLRNC AFTER FORGETTING TO CHANGE TO TWR FREQ. A DAWN APCH AND LNDG.

Narrative: CAPT AND COPLT VERY FATIGUED AFTER A LONG NIGHT OF FLYING. HANDED OVER TO TWR, BUT FORGOT TO CHK ON TO THE NEW FREQ. LANDED AND THEN CALLED GND CTL. GND CTLR DID NOT SEEM UPSET. WE ASSUME TWR STILL ISSUED A CLRNC TO LAND, EVEN THOUGH WE WERE NOT ON FREQ TO HEAR IT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.