5.1 Calling Procedures & Frequency Discipline
Key Takeaways
- Listen on the desired channel long enough to avoid harmful interference; if interference seems likely, wait for the first break
- Distress, urgency, or safety traffic may interrupt lower-priority transmissions at any time
- Always speak the called station first, then THIS IS, then the calling station’s identifier
- Single-station call order: called (≤3 times), THIS IS, calling (≤3 times), frequency, OVER—e.g. Toronto Tower / Cessna 185 FADT on 118.7
- Aircraft usually initiate contact with ground; ground may call aircraft in its service area and sets order by message priority when several call at once
5.1 Calling Procedures & Frequency Discipline
Quick Answer: Before you transmit, listen long enough to avoid harmful interference—if someone is talking, wait for the first break. Distress, urgency, or safety may interrupt lower priority anytime. Format is always called station first, then THIS IS, then you. A single-station call is: called (≤3), THIS IS, calling (≤3), frequency, OVER. Use ALL STATIONS for a general call; multiple stations answer in the order called. Aircraft usually start contact with ground; ground may call aircraft in its area and decides transmit order by priority.
RIC-21 §5.7 Radiotelephone Calling Procedure is the core “how do I get on frequency without wrecking the channel?” chapter of the ROC-A. Examiners test the listen rule, the called-first format, the five elements of a single-station call, ALL STATIONS and multiple-station variants, and who initiates and controls the order of traffic.
Who establishes contact?
In general, it is up to the aircraft station to establish communication with the aeronautical ground station. The aircraft may call when it comes within the operational service area of that ground station. However, a ground station may also establish communication with an aircraft station within its operational service area.
When an aeronautical ground station receives calls from several aircraft stations at approximately the same time, the ground station decides the order in which those stations may transmit their traffic. That decision shall be based on the priority status of the messages (see RIC-21 §4.1 priorities: distress first, then urgency, then lower classes of traffic).
| Situation | Who acts |
|---|---|
| Typical aircraft → ground contact | Aircraft initiates when in the ground station’s service area |
| Ground needs the aircraft | Ground may call aircraft already in its service area |
| Several aircraft call nearly together | Ground orders who transmits next, by message priority |
This pairs with §4.3 control of communications: in aircraft–ground exchanges, the ground station normally retains control of order, time, frequency, and duration (except distress/urgency control rules). Calling procedure is how you enter that controlled channel cleanly.
Frequency discipline: listen before transmit
Before transmitting, operators shall listen to the desired communication channel for a period long enough to satisfy themselves that their transmission will not cause harmful interference to communications already in progress.
- If such interference seems likely, operators shall wait for the first break in the transmission.
- Exception: a station which has distress, urgency or safety communications to transmit is entitled to interrupt, at any time, a transmission of lower priority that is in progress.
Exam traps:
| Wrong idea | RIC-21 rule |
|---|---|
| “Key up immediately if you need tower” | Listen first; wait for a break unless higher priority |
| “Only MAYDAY may interrupt” | Distress, urgency, or safety may interrupt lower priority |
| “Any flight-safety chat may break in anytime” | Only the higher priority classes may interrupt; ordinary traffic waits |
| “Listen for one second is always enough” | Listen long enough to know you will not cause harmful interference |
Half-duplex VHF means when you hold the push-to-talk switch, others may not break in easily. Listening is both legal/spectrum etiquette and safety: you avoid stepping on a clearance, a traffic advisory, or someone else’s emergency.
Universal call format: called station ALWAYS first
The call sign identifier of the station being called is ALWAYS spoken first, followed by the words “THIS IS” and the calling station’s identifier.
Order on every initial call:
- Who you want (called station)
- THIS IS
- Who you are (calling station)
Never reverse it on initial contact (“Cessna FADT Toronto Tower…” is the wrong shape). Call signs should already be phonetic where required by §5.6 (private civil registrations, careful ground names).
Single station call — five elements
When an operator wishes to establish communication with a specific station, transmit the following items in the order indicated:
| # | Element | Rule |
|---|---|---|
| 1 | Call sign of the station called | Not more than three times; once if radio conditions are good |
| 2 | The words THIS IS | Fixed procedural phrase |
| 3 | Call sign of the station calling | Not more than three times; once if conditions are good |
| 4 | The frequency on which the calling station is transmitting | Spoken with number/decimal rules from §5.4 |
| 5 | Invitation to reply | OVER |
Official example (RIC-21)
TORONTO TOWER (repeated up to three times)
THIS IS
CESSNA ONE EIGHT FIVE - FOXTROT ALFA DELTA TANGO
ON FREQUENCY ONE ONE EIGHT DECIMAL SEVEN
OVER
Memorize this structure for the exam:
- Called: Toronto Tower
- THIS IS
- Calling: Cessna 185 Foxtrot Alfa Delta Tango (type + registration style)
- Frequency: 118.7 → “one one eight decimal seven”
- OVER (response expected)
On a good channel you may say the call signs once each; when conditions are poor you may repeat up to three times. Do not invent a fourth repeat as standard practice.
All Stations general call
When an operator wishes to establish communication with any station within range or in a certain area, the call should be made to “ALL STATIONS” using the same procedure as a single station call.
Example (RIC-21):
ALL STATIONS, ALL STATIONS, ALL STATIONS
THIS IS
TORONTO AIR RADIO (three times if necessary)
Use ALL STATIONS for broadcasts that are not directed to one addressee (weather, storm warnings, and other “all stations” traffic also appear in privacy exceptions under §4.2). The structure still keeps called party first (ALL STATIONS) then THIS IS then the originator.
Multiple station call
If more than one station is to be called simultaneously, the call signs of the desired stations may be transmitted in any convenient sequence, followed by THIS IS and the originating station’s call sign. In general, operators replying to a multiple station call should answer in the order in which they have been called.
Example (RIC-21):
CESSNA FOXTROT NOVEMBER INDIA LIMA
PIPER FOXTROT X-RAY QUEBEC QUEBEC
PIPER GOLF LIMA LIMA DELTA
(All repeated three times if necessary) THIS IS
TORONTO TOWER (three times if necessary)
OVER
Reply discipline for the three aircraft: first Cessna FNIL, then Piper FXQQ, then Piper GLLD—order called, not “whoever keys first.”
Putting it together for the ROC-A exam
- Listen → break only for distress/urgency/safety over lower traffic.
- Plan the five-part single call (or ALL STATIONS / multi-call list).
- Called → THIS IS → calling → frequency → OVER.
- Know aircraft usually initiates, ground may call, ground sequences multi-callers by priority.
- Repeat call signs once if good, up to three if needed—not more than three.
Cross-links: speech clarity (§5.1), phonetics/numbers (§5.3–5.4), procedural words (§5.5 / App B), call-sign construction (§5.6). Replies, OUT, and message flow continue in the next sections of §5.7.
Official source
RIC-21 Issue 3, §5.7 Radiotelephone Calling Procedure and §5.7.1 Calling, Innovation, Science and Economic Development Canada (ISED; formerly Industry Canada). Prefer the current RIC-21 text on the ISED website if the circular is revised.
Before transmitting on a desired channel, what must an operator do according to RIC-21 §5.7.1?
In a single-station radiotelephone call under RIC-21, which element comes immediately after the words THIS IS?
Cessna 185 Foxtrot Alfa Delta Tango calls Toronto Tower on 118.7. Which transmission matches the official RIC-21 single-station example structure?