PAPERWORK FOR THE FLC OPERATED SHOWED A DIFFERENT ACFT.

Narrative

BOEING 727 X WAS POSITIONED AT GATE FOR SCHEDULED PART 121 OP. ALL PAPERWORK; FLT PLAN; AND AWABS DATA WAS FOR SHIP Y ACFT WAS CHANGED DURING THE NIGHT. THE DISPATCHER DID NOT CHANGE PAPERWORK. NOT DISCOVERED UNTIL ARR IN ATL. SUPPLEMENTAL INFO FROM ACN 297663: ALL CHKLISTS FROM PREFLT TO THE ENG SHUTDOWN WERE ACCOMPLISHED WITH NO DISCREPANCIES. ALL PHASES OF FLT OCCURRED SAFELY AND NO DISCREPANCIES WERE NOTED. HOWEVER; PRIOR TO RELEASE FROM OUR TRIP WE WERE; INFORMED FROM OUR CHIEF PLT THAT WE HAD FLOWN THE WRONG AIRPLANE. WE WERE INFORMED THAT THE BTR STATION HAD PULLED THE WRONG 727 ACFT TO THE GATE. THE 727 ACFT THAT WE WERE TO FLY TO ATLANTA WAS STILL PARKED ON THE RAMP IN BTR. AS A RESULT OF THE ERROR AT BTR; WE HAD PREFLTED AND FLOWN SHIP X WHEN WE SHOULD HAVE FLOWN SHIP Y. THE SIGNIFICANCE IN THIS IS THAT THE TKOF DATA WAS COMPUTED FOR A DIFFERENT ACFT WITH A DIFFERENT BASIC WT. IF WE HAD BEEN HEAVY IT MIGHT HAVE HAD AN ADVERSE AFFECT ON OUR TKOF PERFORMANCE. SINCE I DON'T HAVE THE DATA TO COMPARE; I CAN'T SAY DEFINITIVELY THAT THERE EVER WAS OR COULD HAVE BEEN A SAFETY PROB. THE OBVIOUS LESSON IS TO ALWAYS CHK THAT YOUR PAPERWORK IS FOR THE CORRECT ACFT #.