Active seat back for aircraft

Described are active seat, energy absorbing, backs (10) for a passenger seat having a seat back (16) with a first pivot location, at least one active system (12) coupled to the pivot location, and at least one sensing circuit (14) electrically connected to the at least one active system and arranged to monitor for crash scenarios and to transmit a signal to the at least one active system when such a scenario is detected; a head rest (24) may coupled to the passenger seat back (16) and comprise a second pivot location (22): in use, the passenger seat back or the seat back and head rest or the head rest may be rotated aft when the at least one active system receives the signal from the at least one sensing circuit.