Pre-Flight - Aviation Meteorology Tip for Pilots! ATC Weather Assistance

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from the Transport Canada Aeronautical Information Manual (TC AIM), MET1.3.8

ATC will issue information on significant weather and assist pilots in avoiding weather areas when requested. However, for reasons of safety, an IFR flight must not deviate from an assigned course or altitude/flight level without a proper ATC clearance. When weather conditions encountered are so severe that an immediate deviation is determined to be necessary, and time will not permit approval by ATC, the pilot's emergency authority may be exercised. However, when such action is taken, ATC should be advised as soon as practicable of the flight alteration.

When a pilot requests clearance for a route deviation or for an ATC radar vector, the controller must evaluate the air traffic situation in the affected area and co-ordinate with other controllers before replying to the request when ATC operational boundaries have to be crossed. It should be remembered that the controller's primary function is to provide safe separation between aircraft. Any additional service, such as weather avoidance assistance, can only be provided to the extent that it does not detract from the primary function. Also note that the separation workload for the controller generally increases when weather disrupts the usual flow of traffic. ATC radar limitations and frequency congestion is also a factor in limiting the controller's capability to provide additional services. For additional information, consult your TC AIM MET Section.

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