a seating unit for a passenger vehicle , especially an aircraft , has a reclinable seat back connected to a seating portion by a hinge . a slider is mounted in a guide track and supports the hinge . a pivotally connected front strut supports the seating portion at a location in front of the hinge . a pivotally connected rear strut supports the seat back at a location spaced apart from the hinge . as the slider along the guide track , the seat back moves to an orientation substantially coplanar with the seating portion so as to provide a flat surface for a sleeping passenger .