Radiotelephony - Procedures, Phraseology and Frequencies
Structure of a call
Every transmission answers four questions: who you are calling, who you are, where you are, and what you want. Use the phonetic alphabet for registration or call signs, speak digits individually, and say "decimal" for the point. Standard replies have precise meanings: "roger" means received, "wilco" means will comply, "affirm" answers yes, "standby" means wait. "Roger" is not a readback.
Readbacks
Read back clearances and instructions that affect safety: hold-short instructions, runway assignments, altitudes, headings, frequencies and altimeter settings. A partial readback is not acceptable. Listen before transmitting, keep transmissions short, and never block a frequency with a long explanation.
Frequencies and emergency
121.5 MHz is the emergency frequency. Uncontrolled aerodromes in Canada commonly use an aerodrome traffic frequency (ATF) around 123.2 MHz, and mandatory frequency (MF) aerodromes have their own published frequency in the CFS - always confirm rather than assume. At uncontrolled fields, make position reports that name the aerodrome, your call sign, your position and altitude, and your intentions.
RPAS in controlled airspace
The authorization for controlled airspace comes first; radio communication is how you stay compliant while inside. Identify yourself as a remotely piloted aircraft, state position, altitude and intentions, monitor the frequency and comply with instructions. If radio contact is lost, leave controlled airspace by the shortest route and land, then notify the unit.
Traps
- Replying "roger" to a hold-short instruction.
- Using the wrong aerodrome frequency because it was assumed.
- Long, informal transmissions that block other traffic.
Worked example
"Centre, drone Alpha Bravo Charlie, five miles west of the airport at 300 feet, request transit through the control zone" - called station, call sign, position, altitude, request.