Airworthiness Directives; Airbus Model A319, A320, and A321 Series Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Airbus Model A319, A320, and A321 series airplanes, that currently requires revising the FAA-approved Airplane Flight Manual (AFM) to increase monitoring of the flight path of the airplane to detect certain software anomalies of the flight management guidance system, and take appropriate corrective actions. This amendment adds a requirement to either modify the existing on-board replaceable modules of the flight management guidance computers (FMGC) to incorporate software changes, or replace the FMGC's with new, improved FMGC's; which would terminate the requirements for the AFM revision. This amendment is prompted by the issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent erroneous navigational calculations, which could result in an increased risk of collision with terrain or other airplanes.