On 15 March 2011, an ATR 72-200 being operated by Irish Company Air Contractors on a non revenue positioning flight from Edinburgh to Paris CDG in night VMC with just the two pilots on board began to experience roll and directional control difficulties as the aircraft accelerated upon reaching the planned cruise altitude of FL230. A ‘PAN call was made to ATC and a return to Edinburgh was made with successful containment of the malfunctioning flying controls.