Airworthiness Directives; Airbus Model A300 B2 and B4 Series Airplanes; A300 B4-600, B4-600R, and F4-600R (Collectively Called A300-600) Series Airplanes; and Model A310 Series Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to all Airbus Model A300 B2 and B4 series airplanes; A300 B4-600, B4-600R, and F4-600R (collectively called A300-600) series airplanes; and Model A310 series airplanes. This amendment requires revising the Airplane Flight Manual to advise the flightcrew to don oxygen masks as a first and immediate step when the cabin altitude warning horn sounds. This action is necessary to prevent incapacitation of the flightcrew due to lack of oxygen, which could result in loss of control of the airplane. This action is intended to address the identified unsafe condition.