(b) A carrier that provides advance seat assignments shall comply with the requirements of paragraph (a) of this section by any of the following methods:

(1) The carrier may “block” an adequate number of the seats used to provide the seating accommodations required by this section.

(i) The carrier shall not assign these seats to passengers not needing seating accommodations provided under this paragraph until 24 hours before the scheduled departure of the flight.

(ii) At any time up until 24 hours before the scheduled departure of the flight, the carrier shall assign a seat meeting the requirements of this section to an individual who requests it.

(iii) If an individual with a disability does not make a request at least 24 hours before the scheduled departure of the flight, the carrier shall meet the individual’s request to the extent practicable, but is not required to reassign a seat assigned to another passenger in order to do so.

(2) The carrier may designate an adequate number of the seats used to provide seating accommodations required by this section as “priority seats” for individuals with disabilities.

(i) The carrier shall provide notice that all passengers assigned these seats (other than passengers with disabilities listed in paragraph (a) of this section) are subject to being reassigned to another seat if necessary to provide a seating accommodation required by this section. The carrier may provide this notice through its computer reservation system, verbal information provided by reservation personnel, ticket notices, gate announcements, counter signs, seat cards or notices, frequent-flier literature, or other appropriate means.

(ii) The carrier shall assign a seat meeting the requirements of this section to an individual who requests the accommodation and checks in at least one hour before the scheduled departure of the flight. If all designated priority seats that would accommodate the individual have been assigned to other passengers, the carrier shall reassign the seats of the other passengers as needed to provide the requested accommodation.

(iii) If the individual with a disability does not check in at least an hour before the scheduled departure of the flight, the carrier shall meet the individual’s request to the extent practicable, but is not required to reassign a seat assigned to another passenger in order to do so.