FAA Seat and Aisle Regulations
Sec. 25.815 Width of aisle.The passenger aisle width at any point between seats must equal or exceed the values in the following table:
|Passenger seating capacity
||Minimum passenger aisle width (inches)
|Less than 25 in. from floor
||25 in. and more from floor
|10 or less
|11 through 19
|20 or more
Sec. 25.817 Maximum number of seats abreast.On airplanes having only one passenger aisle, no more than three seats abreast may be placed on each side of the aisle in any one row.
Sec. 25.785 Seats, berths, safety belts, and harnesses.(a) A seat (or berth for a nonambulant person) must be provided for each occupant who has reached his or her second birthday.
(c) Each seat or berth must be approved.
(f) Each seat or berth, and its supporting structure, and each safety belt or harness and its anchorage must be designed for an occupant weight of 170 pounds, considering the maximum load factors, inertia forces, and reactions among the occupant, seat, safety belt, and harness for each relevant flight and ground load condition (including the emergency landing conditions prescribed in §25.561).