Airworthiness Directives; Airbus Airplanes

We are adopting a new airworthiness directive (AD) for certain Airbus Model A318, A319, and A320 series airplanes and Model A321-111, -112, -131, -211, -212, -213, -231, -232 airplanes. This AD requires revising the airplane flight manual (AFM) to provide guidance to the flight crew for emergency procedures when erroneous airspeed indications are displayed on the back-up speed scale (BUSS). This AD was prompted by a determination that, when two angle of attack (AoA) sensors are adversely affected by icing conditions at the same time, data displayed on the BUSS could be erroneous. We are issuing this AD to address the unsafe condition on these products.