In a block of two seats side by side which can be converted individually between a chair configuration and a horizontal flat bed configuration, the two seats are arranged and oriented substantially in the same direction, the longitudinal axes of each of the seats in the bed configuration converge towards a point situated behind the seats at a distance such that upper parts of the seat backs and of the head rests are superposed in a head area of the block. The bed planes of the seats of a block are vertically offset and extended by rest surfaces of the foot areas arranged in lateral columns arranged to the sides of the head area in the region of the rear shell of a block situated in front, allowing to reduce the seat pitch without affecting comfort and allowing an improved layout of a cabin for transporting passengers.