ROC-A Study Guide

The official study guide published by Innovation, Science and Economic Development Canada (ISED) that outlines the essential knowledge, regulations, and operating procedures needed to pass the ROC-A exam and legally operate aviation radios in Canada.

---

---

Communication Priorities

When you’re transmitting on aviation radio, some messages have higher priority than others. The order is simple:

1. Distress calls (Mayday – life-threatening situations)
2. Urgency calls (Pan-Pan – important but not immediately life-threatening)
3. Radio direction-finding messages
4. Flight safety messages (traffic advisories, navigational info, etc.)
5. Weather messages
6. Routine operational messages that support regular flight operations
7. Authorized UN-related messages
8. Government messages with requested priority
9. Telecommunication service messages (technical or administrative)
10. All other normal aeronautical communications

In practice, for a pilot: Distress and urgency always come first. Everything else fits below those based on safety and operational importance.

Privacy of Communications

Anything you hear on the aviation radio is considered private, even though it’s broadcast openly. You’re not allowed to share the details of any communication you hear unless:

• you’re the intended recipient,
• you’re passing it along to someone authorized to receive it,
• or it’s necessary for safety (e.g., distress or emergency messages).

Distress, urgency, general safety messages, and broadcasts to “ALL STATIONS” (like weather warnings) are exceptions—those can be freely repeated when needed.

Breaking radio-privacy rules can lead to serious fines or penalties, so the guiding rule is simple:

If it’s not your message, don’t repeat it.

Control of Communications

When you’re talking on the radio, someone is always in charge of how the communication flows. Here’s the simple rule:

On the ground → the ground station controls the communication.
In the air (aircraft-to-aircraft) → the aircraft being called controls the communication.

What this means in practice:

• Ground stations decide which frequency to use and when you should talk.
• Aircraft must follow the ground station’s instructions on frequency changes, timing, and when to start or stop transmitting.
• The only exception is during distress or urgency calls, where the station making the emergency call takes control.

Inside the aircraft, the radio is ultimately under the control of the pilot (or another person the pilot designates).

When aircraft talk to each other, the aircraft being called decides whether to accept the frequency the calling aircraft suggests.

• If it agrees, it simply acknowledges and switches.
• If it doesn’t agree, it tells the calling aircraft which frequency to use instead.

Simple Examples
1. Ground station calling an aircraft - Ground station has control.

OTTAWA RADIO:
“Piper C-FXQQ, this is Ottawa Radio. Go ahead on tower frequency 122.1. Over.”

2. Aircraft calling a ground station - Ground station still has control.

Piper C-FXQQ:
“Ottawa Radio, this is Piper C-FXQQ on frequency 122.1. Over.”

3. Aircraft calling another aircraft - The aircraft being called has control.

Piper C-FXQQ:
“Cessna C-FXQT, this is Piper C-FXQQ on frequency 119.7. Over.”

If the called aircraft wants to change frequencies:

Cessna C-FXQT:
“Piper C-FXQQ, this is C-FXQT. Change to SAR frequency 123.6. Out.”

For all example above - the full Phonetic Alphabet is to be used in practice.  Using the last example above, it would be:

PIPER CHARLIE FOXTROT X-RAY QUEBEC QUEBEC
THIS IS
CESSNA CHARLIE FOXTROT X-RAY QUEBEC TANGO
CHANGE TO SEARCH AND RESCUE FREQUENCY ONE TWO
THREE DECIMAL SIX
OUT

Superfluous Communications and Interference

Aviation radio is for important, safety-related, and operational messages only. Anything unnecessary, casual, or off-topic shouldn’t be transmitted.

You must not use:

• unnecessary chatter,
• jokes or casual conversation,
• profane or inappropriate language.

Using the radio for anything outside safety and flight operations, or interfering with another station’s communication, can lead to serious penalties.

Never interrupt another transmission unless you have a higher-priority message such as:

• Mayday (distress)
• Pan-Pan (urgency)
• another officially recognized priority call

In short: keep transmissions professional, necessary, and clear.

False Distress Signals

You must never intentionally transmit a false distress call of any kind.

Knowingly sending a fake “Mayday,” “Pan-Pan,” or any other false emergency message is a serious offence and can result in major fines or criminal penalties.

The rule is simple:

Only declare an emergency if an actual emergency exists.

Speech Transmission Techniques

Clear radio communication depends on how you speak as much as what you say. Radios can distort certain consonants and make similar-sounding words blend together, so good technique is essential.

When transmitting, speak clearly, calmly, and at a steady pace. Avoid shouting, rushing, or letting your words run together. The goal is to sound natural, but crisp and easy to understand.

Keep these key points in mind:

• Speed: Speak at a normal, steady rate—not too fast and not too slow. Remember, the person listening may need to write your message down.
• Rhythm: Use the natural rhythm of normal conversation. Pronounce each word carefully and avoid slurring or clipping sounds.
• Clarity: Keep your voice relaxed, articulate consonants clearly, and avoid exaggerated emphasis or dramatic tone.

Think of it this way: If your message is easy to understand the first time, everyone’s job becomes easier and safer.

Time and Date

Aviation uses the 24-hour clock for radio calls. Time is always sent as four digits:

• The first two digits = hour after midnight
• The last two digits = minutes past the hour

Examples:

• 12:45 a.m → 0045
• 12:00 noon → 1200
• 11:45 p.m → 2345
• 12:00 midnight → 0000 or 2400
• 1:30 a.m → 0130
• 1:45 p.m → 1345
• 4:30 p.m → 1630

To avoid confusion with time zones, aviation normally uses UTC (also called Zulu time). When flights or operations happen only within a single time zone, local time can be used.

If you need to send both date and time, use six digits:

• First two = day of the month
• Next four = time (24-hour format)
• Add a letter for the time zone if required (e.g., Z, E for EST, P for PST)

Examples:

• 16th day at 12:00 noon EST → 161200 E
• 24th day at 2:45 a.m PST → 240245 P

ITU Phonetic Alphabet

The ITU phonetic alphabet is used worldwide to make radio communication clearer—especially when spelling call signs, names, or any words that could be misunderstood. Every pilot must know it well enough to use it instantly, especially in poor radio conditions.

You use the phonetic alphabet whenever:

• spelling aircraft registration
• reading back clearances
• transmitting unfamiliar names or words
• communication quality is weak

Phonetic Alphabet

Letter	Word	Pronounced
A	Alfa	AL-FAH
B	Bravo	BRAH-VOH
C	Charlie	CHAR-LEE / SHAR-LEE
D	Delta	DELL-TAH
E	Echo	ECK-OH
F	Foxtrot	FOKS-TROT
G	Golf	GOLF
H	Hotel	HOH-TELL
I	India	IN-DEE-AH
J	Juliett	JEW-LEE-ETT
K	Kilo	KEY-LOH
L	Lima	LEE-MAH
M	Mike	MIKE
N	November	NO-VEM-BER
O	Oscar	OSS-CAH
P	Papa	PAH-PAH
Q	Quebec	KEH-BECK
R	Romeo	ROW-ME-OH
S	Sierra	SEE-AIR-RAH
T	Tango	TANG-GO
U	Uniform	YOU-NEE-FORM / OO-NEE-FORM
V	Victor	VIK-TAH
W	Whiskey	WISS-KEY
X	X-ray	ECKS-RAY
Y	Yankee	YANG-KEY
Z	Zulu	ZOO-LOO

 

Numbers (How to Say Them on the Radio)

Number	Said As
0	ZE-RO
1	WUN
2	TOO
3	TREE
4	FOW-ER
5	FIFE
6	SIX
7	SEV-EN
8	AIT
9	NIN-ER

 

Additional terms:

• Decimal → DAY-SEE-MAL
• Hundred → HUN-DRED
• Thousand → TOW-SAND

Transmission of Numbers

When transmitting numbers on the radio, say each digit separately, unless the number is a whole thousand.

General Rules

• Say each digit individually
  • 10 → “one zero”
  • 75 → “seven five”
  • 100 → “one zero zero”
  • 5800 → “five eight zero zero”
• For whole thousands, say the digits, then “thousand”
  • 11,000 → “one one thousand”
• If there's a decimal, say “decimal”
  • 121.5 → “one two one decimal five” 

Money (if ever transmitted)

Say the units in the order written.

• $17.25 → “dollars one seven decimal two five”
• $0.75 → “decimal seven five”

Altitude and Flight Levels

• Altitudes are said in thousands and hundreds
  • 2700 → “two thousand seven hundred”
• Flight levels use separate digits
  • FL265 → “flight level two six five”

Aircraft Types, Wind, and Clouds

Some aviation numbers are spoken as groups, not digit-by-digit:

• Flight 320 → “flight three twenty”
• DC10 → “D C ten”
• 34BKN → “thirty four hundred broken”
• Wind 270/10 → “wind two seven zero degrees one zero knots”

Time (UTC / Zulu)

• 0920Z → “zero niner two zero zulu”
• 09 → “nine minutes past the hour”

Headings

Always spoken as three digits:

• 005° → “heading zero zero five”
• 350° → “heading three five zero”

Headings are:

• Magnetic in the Southern Domestic Airspace
• True in the Northern Domestic Airspace

(Don’t worry—flight training will explain this in detail.)

Aerodrome Elevation

Say the elevation in feet, prefixed with “field elevation”:

• 150 → “field elevation one five zero”
• 3500 → “field elevation three thousand five zero zero”