What are blocked seats?

On occasion, Continental will withdraw or "block" some seats from being sold. There are several reasons for this occurene. For instance, when Economy Class on a flight is booked over capacity and the premium cabin (i.e. First Class or BusinessFirst) is not, some premium cabin seats may be released in order reduce the chance that some customers will be denied boarding. Continental flights that are scheduled to be twelve hours or more, up to four BusinessFirst seats may be reserved for crew rest. These seats may not be sold or occupied for any purpose other than crew rest.