The pilot shall obtain
ATC clearance for controlled flight or a portion of a flight, for which a flight plan shall be filed. With
ATC clearance, the pilot receives permission to conduct his flight under specific conditions. While guiding the movements of the flight subject to its control,
ATC unit may establish in detail the progress of the flight, especially the flight path and level, when issuing the corresponding clearances. Whenever a pilot requests air traffic control clearance involving priority because of urgent reasons, he shall specify these reasons in his application. The pilot is not permitted to deviate from the
ATC clearance last issued and confirmed, unless a new
ATC clearance has been issued. This does not apply to emergency situations which require immediate decision by the pilot. In these cases the pilot shall notify the competent
ATC unit without delay and obtain a new
ATC clearance. An aircraft operating on a controlled aerodrome shall not taxi on the maneuvering area without
ATC clearance from the competent
ATC unit and shall comply with any instructions given by that unit.