Summary
We propose to adopt a new airworthiness directive (AD) for certain Bombardier, Inc., Model CL-600-2B16 (CL-604 Variant) airplanes. This proposed AD was prompted by reports of in-service incidents regarding the loss of all air data system information provided to the flightcrew. This proposed AD would require revising the airplane flight manual to provide ``Unreliable Airspeed'' procedures to the flightcrew to stabilize the airplane's airspeed and attitude for continued safe flight and landing. We are proposing this AD to address the unsafe condition on these products.