An adjustable aircraft passenger seat, comprising: a seat bottom; a legrest adjustable in angle relative to the seat bottom; a seatback adjustable in angle relative to the seat bottom, the seatback segmented into a lower seatback and an upper seatback, the lower seatback adjustable in angle relative to the seat bottom and the upper seatback adjustable in angle relative to the lower seatback; and a headrest adjustable in height relative to the upper seatback; wherein the adjustable aircraft passenger seat is adjustable to achieve an upright sitting position for taxi, take-off and landing, and an in-bed lounge sitting position in which the legrest and seat bottom are coplanar, the lower seatback is at an angle to the seat bottom, and the upper seatback is at an angle to the lower seatback, and wherein a first actuator is dedicated for lower seatback movement, a second actuator is dedicated for upper seatback movement, and a third actuator dedicated for headrest movement; and wherein the upper seatback is pivotably attached at one end to the lower seatback and characterised in that the second actuator is horizontally-oriented on a backside of the upper seatback to drive a rotating gear meshed with an arcuate toothed guide of the lower seatback to move the gear along a length of the arcuate toothed guide to adjust an angle of the upper seatback relative to the lower seatback. a seat bottom; a legrest adjustable in angle relative to the seat bottom; a seatback adjustable in angle relative to the seat bottom, the seatback segmented into a lower seatback and an upper seatback, the lower seatback adjustable in angle relative to the seat bottom and the upper seatback adjustable in angle relative to the lower seatback; and a headrest adjustable in height relative to the upper seatback; wherein the adjustable aircraft passenger seat is adjustable to achieve an upright sitting position for taxi, take-off and landing, and an in-bed lounge sitting position in which the legrest and seat bottom are coplanar, the lower seatback is at an angle to the seat bottom, and the upper seatback is at an angle to the lower seatback, and wherein a first actuator is dedicated for lower seatback movement, a second actuator is dedicated for upper seatback movement, and a third actuator dedicated for headrest movement; and wherein the adjustable aircraft passenger seat is adjustable to achieve an upright sitting position for taxi, take-off and landing, and an in-bed lounge sitting position in which the legrest and seat bottom are coplanar, the lower seatback is at an angle to the seat bottom, and the upper seatback is at an angle to the lower seatback, and wherein a first actuator is dedicated for lower seatback movement, a second actuator is dedicated for upper seatback movement, and a third actuator dedicated for headrest movement; and wherein the upper seatback is pivotably attached at one end to the lower seatback and characterised in that the second actuator is horizontally-oriented on a backside of the upper seatback to drive a rotating gear meshed with an arcuate toothed guide of the lower seatback to move the gear along a length of the arcuate toothed guide to adjust an angle of the upper seatback relative to the lower seatback.