Transport Canada CF-2019-24

Requires incorporation of Airplane Flight Manual (AFM) procedures that will allow the crew to stabilize the airplane’s airspeed and attitude for continued safe flight and landing in cases of loss of air data system information.  This action stems from reports of loss of all air data system information provided to the crew. The air data system information was recovered as the aircraft descended to lower altitudes. An investigation determined that the root cause in all events was high altitude icing (ice crystal contamination). If not recognized and addressed, this condition may affect continued safe flight and landing.