SA CIVIL AVIATION REGULATIONS
PART 91: GENERAL AVIATION AND OPERATING FLIGHT RULES
91.06.16 Mandatory radio communication in controlled airspace

The PIC of an aircraft shall ensure that before the aircraft enters a controlled airspace, two-way radio contact is established with the responsible ATSU on the designated radio frequency, and shall ensure, while the aircraft is within, and until it leaves, the controlled airspace, that continuous radio watch is maintained and that such further two-way radio communication as such ATSU may require, is established: Provided that

(a) the ATSU may permit an aircraft not capable of maintaining continuous two-way radio communication, to fly in the control area, TMA, control zone or aerodrome traffic zone for which it is responsible, if traffic conditions permit, in which case the flight shall be subject to such conditions as such ATSU deems necessary to ensure the safety of other air traffic; and

(b) in the case of radio failure, a flight for which an air traffic service flight plan was filed and activated by the ATSU on receipt of a departure time, may continue in controlled airspace if the communication failure procedures specified in Document SA-CATS 91 are complied with.

Radio communication failure (RCF) procedures – General

(1) When an aircraft fails to establish contact with the aeronautical station on the designated frequency, it shall attempt to establish contact on another frequency appropriate to the route. If this attempt fails, the aircraft shall attempt to establish communication with other aircraft or other aeronautical stations on frequencies appropriate to the route. In addition, an aircraft shall monitor the appropriate VHF frequency for calls from nearby aircraft or aeronautical stations.

(2) If these attempts fail, the aircraft station shall continue to transmit position reports and its intentions as appropriate on the designated frequency or frequencies, preceded by the phrase “Transmitting Blind”. Such messages shall be transmitted twice and, if necessary, include the addressee(s) for which the message is intended.

(3) If no communication is received or other indication that one-way communications are possible, the aircraft shall set its transponder to Code 7600 and proceed with the lost communications procedures.

(4) In any case, whereby an aircraft having suffered a communication failure in flight arrives at an aerodrome, it shall keep a watch for such instructions as may be issued by visual signals from the aerodrome control tower or other facility.