第4條
The radio station in an aircraft shall not be operated so as to cause interference which impairs the efficiency of aeronautical telecommunications or navigational services, and in particular emissions shall not be made except as follows: (a) emissions of the class and frequency for the time being in use, in accordance with general international aeronautical practice, in the airspace in which the aircraft is flying; (b) distress, urgency and safety messages and signals, in accordance with general international aeronautical practice; (c) messages and signals relating to the flight of the aircraft, in accordance with general international aeronautical practice; (d) such public correspondence messages as may be permitted by or under the aircraft radio station licence referred to in paragraph (1) of this Article.