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 ACT of this fact, since acknowledgement of the clearance alone will be taken by a controller as indicating acceptance; e.g. , on receiving a clearance for takeoff, the pilot should acknowledge the clearance and takeoff without undue delay or , if not ready to takeoff at that particular time, inform ACT of the pilot's intentions, in which case the clearance may be changed or cancelled.  A pilot shall comply with an ACT instruction which is directed to and received by the pilot, provided the safety of the aircraft is not jeopardized.