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 . <EOS>