Passenger accommodations are easily and rapidly convertible from conventional seats to bunk beds and back. A support structure (9) supports a seat pad (13) and a seat pad extension (15) and also rotatably supports a seat back (5). The seat pad extension (15) and seat back (5) are partially supported by the support structure (9) of a row of seats ahead of the convertible seats when the convertible seats are converted to bunk beds. A third bunk bed (21,23) may be unfolded under the lower bunk bed formed by the seat pad (13, 15).