An air outlet valve for use in an aircraft is adapted during normal operation of the aircraft as a component of a cabin pressure control system for adjusting a desired pressure level in an aircraft cabin to remove air from an interior of the aircraft into the environment around the aircraft. The air outlet valve is further adapted during emergency ventilation operation of the aircraft as a component of a system for emergency ventilation of the aircraft cabin to introduce air from the environment around the aircraft into the interior of the aircraft. The air outlet valve comprises a nose-side valve flap, which is pivotable about an axis and is adapted to open or close a nose-side portion of an air outlet valve aperture, and a tail-side valve flap, which is pivotable about an axis and is adapted to open or close a tail-side portion of the air outlet valve aperture. A portion of the tail-side valve flap that in the open state of the tail-side valve flap projects into an air stream flowing around an aircraft skin during cruising of the aircraft is greater than a portion of the nose-side valve flap that in the open state of the nose-side valve flap projects into the air stream flowing around the aircraft skin during cruising of the aircraft.