FLC DEPARTS IN WRONG ACFT; NOT NOTING AN ACFT CHANGE.

Narrative

SCHEDULED TO DEPART FAIRBANKS TO SEA WITH STOP OF 47 MINS AT ANC. THIS FLT IS NORMALLY A 'THROUGH' FLT WITHOUT AN ACFT CHANGE. WE FLEW AN AUTOLAND APCH AT ANC DUE TO FOG FOR WHAT AMOUNTED TO A NORMAL TIME ON THE GND. ENRTE TO SEA WE CONTACTED SYS MAINT TO RPT A MINOR DISCREPANCY. WE GIVE MAINT OUR TAIL NUMBER AS PER NORMAL PROCS AND AT THAT TIME FOUND THE NUMBER DID NOT AGREE WITH OUR PAPERS FOR THE LEG TO SEA. WE LATER FOUND THAT WE SHOULD HAVE HAD A PLANE CHANGE AT ANC BUT IT WAS NOT CAUGHT BY US OR THE GND PERSONNEL. THERE WAS NO SAFETY PROB AS OUR WTS WERE WELL WITHIN LIMITS BUT IT MEANT WE FLEW AN ACFT WITHOUT PROPER PAPERS. THIS WAS AN UNUSUAL EVENT; CHANGING ACFT; AND WAS OBVIOUSLY MISSED BY EVERYONE! I SUGGESTED TO MY COMPANY THAT OUR RELEASE PAPERS BE HIGHLIGHTED WITH A NOTE TO THE CAPT; BY NAME; NOTING THE NONSTANDARD SIT OF CHANGING AIRPLANES AT ANC. SUCH A CHANGE WOULD BE NOTED IF WE WERE GOING THROUGH A HUB STATION OR ANY STATION WHERE A LAYOVER MIGHT ENTAIL AN ACFT CHANGE; BUT NOT AT ANC AT EARLY AM TIME!