XX --------- XX
 
 
  UPGRADING - INVOLUNTARY
 
Airlines do involuntary upgrading when less space in the lower class, lower class of a flight is overbooked; cancellation of flight, aircraft has to accommodate more passengers in a higher class because of weight problem and failing to operate a flight in accordance with schedule.
 
     
     
             
             
             
             
             
     
     
 
  TRAVEL TERMINOLOGY
 
 
  ALPHABETICAL WISE