Aircraft Flight Operation Regulations Article 131

An aircraft shall be provided with radio communication equipment capable of conducting two-way communications for aerodrome control purposes, for receiving meteorological information at any time during flight; and conducting two-way communication at any time during flight with at least one aeronautical station and any other aeronautical stations on such frequencies as may be prescribed by the appropriate authority.The radio communication equipment required in accordance with the preceding paragraph shall provide for communication on the aeronautical emergency frequency 121.5.