Radio Calls, Readability and Emergencies

Radio is for concise shared awareness

Aeronautical radio is not a casual conversation channel. It is a disciplined way to make position, intention, traffic and emergency information understandable to other airspace users.

A remote pilot should know the relevant frequency, listen before transmitting, use standard phraseology and keep calls short enough that other traffic can use the channel.

A radio frequency drawn as a time strip with two lanes, other traffic above and you below. A playhead moves along it. First another station transmits while you listen. When the channel is clear you press transmit and speak five short parts: who you call, who you are, where you are, what you are doing and what you need. You release and listen again, and the other station can use the channel. With the long call option the same call is padded with extra chatter, so it is still going when the other station needs to transmit, and that call is blocked.

Radio waves are line-of-sight limited

VHF aeronautical radio is mainly line of sight. Height, terrain, antenna placement, aircraft attitude and obstacles all affect whether another station can hear you.

A handheld or remote pilot station radio may not perform like an aircraft-mounted radio. The operator should understand the equipment, battery state, antenna orientation and range limitations before relying on it.

Schematic, not to scale, with the Earth's curvature exaggerated. A VHF transmitter mast on the left sends a signal along a straight line to a light aircraft. As the aircraft moves further away the straight path is first blocked by a hill and then by the curve of the Earth; the shaded area behind them is out of line of sight. A low cloud on the path does not block the signal. A higher receiver keeps line of sight to a greater distance. This illustrates the principle only; it does not predict real radio coverage.

Listen first, then make the call useful

Before transmitting, listen to avoid stepping on another call. Then keep the message relevant: who you are calling, who you are, where you are, what you are doing and what you need.

Unnecessary radio traffic can hide important traffic calls. Long or vague calls also increase workload for other airspace users.

• Use standard phraseology and plain numbers.
• Avoid slang and long explanations on frequency.
• If uncertain, pause and prepare the message before transmitting.

CTAF calls build shared traffic awareness

A CTAF is used so nearby aircraft can build a shared picture of traffic and intentions. A remote pilot operating in an environment where radio is required or operationally necessary should make calls that help other pilots understand where the RPA is and what it is doing.

The call should match the operation. A drone at low level near an aerodrome has different information value from a crewed aircraft in the circuit, but both need to understand each other's position and intention.

Top-down schematic of Kingaroy, a non-towered aerodrome, not to scale. An aircraft approaches from the west and broadcasts on the CTAF at 10 nautical miles inbound. It joins a left-hand circuit and broadcasts on downwind, base and final, lands and broadcasts again when clear of the runway. A drone crew operating west of the aerodrome also broadcasts its position and intentions. A strip under the map lights up the parts of each broadcast in order: location, aircraft type, callsign, position and intentions, then the location again.

Read the Making a CTAF radio call transcript

Clarity matters under pressure

The phonetic alphabet, standard numbers, readability scale, Mayday and Pan Pan formats exist so messages survive stress, noise and time pressure.

If a radio call is needed, plan what you need to say before pressing transmit: who you are calling, who you are, where you are, what you are doing and what you need.

A 12 second loop. Three requirements appear one at a time and are each ticked: age 17 or over, training and assessment, and a current aviation English language proficiency assessment. They merge into a round AROC token issued by CASA. The token then moves aside and links to a person holding a VHF handheld radio. The person presses transmit and radio waves travel to an aircraft overhead, showing that the AROC lets the holder transmit on frequencies used for the safety of air navigation. The holder control swaps the person between a UAV operator with a drone, a ground handler with a baggage cart, and a marshalling attendant with wands. This is a conceptual scene, not a picture of the official certificate. The still frame shows the transmission reaching the aircraft.

Readability and readback protect the message

The readability scale helps a station report how well a transmission can be heard. Readback confirms critical information has been received correctly, especially when instructions, frequencies, locations or emergency details matter.

If a message is unreadable, do not pretend it was understood. Ask for it again or use an approved alternate communication path if the operation allows it.

Mayday and Pan Pan are not ordinary calls

Mayday is used for distress where there is grave and imminent danger requiring immediate assistance. Pan Pan is used for urgency where safety is affected but the situation is not yet distress.

For remote pilots, the exact operational context matters: risk to people, other aircraft, property, airspace, control link, battery state, aircraft position and the ability to recover safely.

Good radio discipline starts before the job

Radio use should be planned in the job pack: frequency, callsign or station identification, expected calls, emergency calls, backup communication and who is responsible for listening and transmitting.

The radio should be checked like other operational equipment: charged, configured, volume set, frequency confirmed and usable at the site.

Practice Questions