Radio call and reply procedure
RIC-21 fixes the sequence for making, answering, and correcting a call so stations never talk over each other.
Calling (RIC-21 5.7.1):
- Called station's call sign (first, always)
- "THIS IS"
- Own call sign
- Initial contact: manufacturer name or type + last four registration letters in phonetics (PSTAR 3.04).
- NAV CANADA advises including type (a Cessna 150 and a Cessna Citation fly very differently).
- High frequency congestion: may drop "THIS IS", transmit only the most important information (NAV CANADA VFR Phraseology, Initial Contact).
- Aircraft generally initiates contact once within ground station's operational service area; ground station may also (RIC-21 5.7).
Call types:
| Call | Format |
|---|---|
| Single station | Called call sign (up to 3 times, once if conditions good), "THIS IS", own call sign (up to 3 times), frequency, "OVER" |
| ALL STATIONS | Same format to "ALL STATIONS": reaches anyone in range or in an area |
| Multiple stations | Call signs in any convenient order, "THIS IS", own call sign. Replies in order stations were called |
Replying:
| Situation | Action |
|---|---|
| Call is for you | Reply asap: GO AHEAD or STAND BY |
| Unsure call is for you | Wait until repeated and understood |
| Unsure who is calling | Reply at once: "STATION CALLING", own identification, "SAY AGAIN", "OVER" |
| Many transmissions | Own call sign alone acceptable (NAV CANADA VFR Phraseology, Readback/Hearback) |
| Unclear, unexpected, not understood | Ask for clarification |
| End of exchange | "OUT" |
- ATS silent on busy frequency: wait (may be on higher-priority task). Call again if call thought missed.
Correcting an error: "CORRECTION", last correct word or phrase, corrected version.
Repeating:
| Need | Say |
|---|---|
| Whole message | "SAY AGAIN" |
| Part before a gap | "SAY AGAIN ALL BEFORE ..." (first word you got correctly) |
| Part between | "SAY AGAIN ... TO ..." (word before the gap, then word after it) |
| Part after a gap | "SAY AGAIN ALL AFTER ..." (last word you got correctly) |
Message format (RIC-21 5.7.4), four parts:
- Call
- Addressee's reply
- Message
- Acknowledgment or ending
- Cyclical: state request or intentions, listen for feedback, acknowledge response (e.g. ATC clearance, pilot readback, ATC hearback) (NAV CANADA VFR Phraseology, General Format of Radio Communication).
- Call sign in each transmission: lets ATS confirm the intended aircraft got the message.
- Subsequent calls in same exchange: "THIS IS" and "OVER" may be dropped, called station's call sign may be abbreviated, if interference unlikely.
Unfamiliar: say "UNFAMILIAR" in new airspace or at new airport: warns ATS you may not be ready for abbreviated, complex, or fast-paced information; unit will try to offer direct or uncomplicated routing.
Traffic: don't use or accept "with the traffic": a cause of communication errors (NAV CANADA VFR Phraseology, Traffic).
Trap: picking "SAY AGAIN ALL AFTER" when words before a gap are needed.
References
- RIC-21 5.7
- RIC-21 5.7.1
- RIC-21 5.7.2
- RIC-21 5.7.3
- RIC-21 5.7.4
- NAV CANADA VFR Phraseology, Initial Contact
- PSTAR 3.04
- NAV CANADA VFR Phraseology, Unfamiliar
- NAV CANADA VFR Phraseology, Readback/Hearback
- NAV CANADA VFR Phraseology, General Format of Radio Communication
- NAV CANADA VFR Phraseology, Traffic