Whenever an ATC clearance is received and accepted by the pilot, compliance shall be made with the clearance. If a clearance is not acceptable, the pilot should immediately inform ATC of this fact since acknowledgement of the clearance alone will be taken by a controller as indicating acceptance. For example, upon receiving a clearance for takeoff, the pilot should acknowledge the clearance and take off without undue delay or, if not ready to take off at that particular time, inform ATC of his or her intentions, in which case the clearance may be changed or cancelled. A pilot shall comply with an ATC instruction that is directed to and received by the pilot, provided the safety of the aircraft is not jeopardized.
A clearance will be identified by the use of some form of the word “clear” in its contents. An instruction will always be worded in such a manner as to be readily identified, although the word “instruct” will seldom be included. Pilots shall comply with and acknowledge receipt of all ATC instructions directed to and received by them (CAR 602.31). It should be remembered that control is predicated on known air traffic only and, when complying with clearances or instructions, pilots are not relieved of the responsibility for practising good airmanship. A clearance or instruction is only valid WHILE IN CONTROLLED AIRSPACE. Pilots crossing between controlled and uncontrolled airspace should pay close attention to the terrain and obstacle clearance requirements.
ATS personnel routinely inform pilots of conditions, observed by others or by themselves, which may affect flight safety and are beyond their control. Examples of such conditions are observed airframe icing and bird activity. These are meant solely as assistance or reminders to pilots and are not intended in any way to absolve the pilot of the responsibility for the safety of