Transport Canada CF-2018-36

Requires incorporation of procedures in the airplane flight manual that allows the crew to stabilize the airplane’s airspeed and attitude for continued safe flight and landing in the event of loss of all air data system information provided to the crew. Prompted by several in-service incidents where this data was unavailable but was recovered when the aircraft descended to lower altitudes. An investigation determined that the root cause in these events was high-altitude icing (ice crystal contamination).