Abstract: An aircraft seat convertible in situ for economy class and business class usage is described herein. In the case of a two-seater convertible seat, arm dividers are movably mounted on a seat frame for positioning thereon according to required widths of seating positions and to eliminate a middle seating position for business usage. Seat backs of two outer seating positions may be provided with mechanisms, such as slidable panels, which operate to vary the widths of the seat backs in the business class position. Alternatively, the seat backs are bodily movable on the seat frame and provided with hinge-mounted side bolsters of a compressible foam material which can be opened outwardly to increase the widths of the backs of the two outer seats with those backs moved to the two-seater business class configuration on the seat frame and the middle seating position eliminated.