What was found
AT FL240, FAS CALLED AND STATED THAT THEY COULD SMELL A THICK, DUSTY, BITTER ODOR. AT FIRST WE (PLTS) SMELLED NOTHING. AT FL180, THEY CALLED BACK AND SAID THE SMELL WAS MOVING FWD AND TRANSITIONED TO A BURNING PLASTIC SMELL. AT THAT TIME WE USED OXY MASKS FOR FLIGHT'S DURATION. BOTH FO AND CA COULD SMELL BURNIMNG SMELL ON GND WITH COCKPIT DOOR OPEN. C/A: ALL WORK AND CORRECTIVE ACTION ON LOG 1084227