What is a SELCAL code?

A SELCAL code is a unique four-letter identifier assigned to each aircraft for selective calling purposes.

How does SELCAL benefit flight crews during long flights?

SELCAL allows crews to avoid constant radio monitoring, alerting them only when ground stations need to communicate.

What should a pilot do if SELCAL equipment becomes inoperative?

The pilot should inform ATC by stating "INOPERATIVE SELCAL" on the relevant frequency.

Is SELCAL used on both HF and VHF frequencies?

Yes, SELCAL operates on both HF and VHF radio systems.

How does SELCAL differ from CPDLC?

SELCAL is an alerting system using audio tones, while CPDLC is a data link system for text-based communication.

SEL (Selective Calling) Procedures

Medium4 min readCommunications

Occasionally Examined

Why this matters

SELCAL procedures reduce pilot workload and fatigue, especially on long flights, by allowing crews to safely monitor radios passively until alerted. This ensures critical messages are not missed while maintaining operational efficiency and safety.

Selective Calling (SELCAL) is an aviation communication system that allows ground stations to alert specific aircraft using coded audio tones, eliminating the need for continuous radio monitoring by flight crews. Each aircraft is assigned a unique SELCAL code, and when this code is transmitted, the cockpit receives a visual and audible alert to prompt the crew to listen to the incoming message.

Quick Check

What is the primary function of the SELCAL (Selective Calling) system in aviation communications?

AI Tutor

Go beyond the textbook.

Ask Avi AI about SEL (Selective Calling) Procedures

In depth

Explanation

How SELCAL Works

SELCAL (Selective Calling) enables ground stations to contact individual aircraft by transmitting a series of coded tones over the radio frequency in use. When the correct SELCAL code is received, the aircraft's SELCAL system triggers a visual indicator and an audible chime in the cockpit. This system is particularly valuable during long-haul flights, especially over oceanic or remote areas where continuous radio listening would be fatiguing.

SELCAL Procedures in Aviation

The aircraft's SELCAL code (four-letter combination) should be included in the flight plan and, if necessary, stated on initial contact: "SELCAL (code)".
If the crew is unsure whether the ground station has the SELCAL code, they must provide it during first contact.
To check SELCAL functionality, the pilot requests: "REQUEST SELCAL CHECK". Upon receiving the alert, the crew replies: "SELCAL OK".
If the SELCAL system fails or is not working, the crew must inform ATC: "INOPERATIVE SELCAL".
A SELCAL check must be re-established every time the frequency changes, ensuring the ground station can still reach the aircraft.
If the SELCAL alert is weak or not received, the pilot should respond: "NEGATIVE SELCAL, TRY AGAIN".

SELCAL vs Other Communication Systems

SELCAL is different from CPDLC (Controller Pilot Data Link Communications), which uses digital text messages rather than audio tones. SELCAL is strictly for alerting the crew to listen to a voice message, not for sending or receiving operational data.

Key Phraseology

"SELCAL (code)" – to provide your code
"REQUEST SELCAL CHECK" – to verify the system
"SELCAL OK" – to acknowledge a successful check
"INOPERATIVE SELCAL" – to report a malfunction
"NEGATIVE SELCAL, TRY AGAIN" – to request a repeat if the alert was not received

The essentials

Key Points

SELCAL allows ground stations to alert specific aircraft using coded tones.

Each aircraft has a unique four-letter SELCAL code included in the flight plan.

SELCAL eliminates the need for continuous radio monitoring by the crew.

A SELCAL check should be requested after each frequency change.

Phraseology includes: "REQUEST SELCAL CHECK", "SELCAL OK", and "INOPERATIVE SELCAL".

If the alert is not received, pilots should say "NEGATIVE SELCAL, TRY AGAIN".

SELCAL is different from CPDLC, which uses digital text messages.

Watch out

Exam Traps & Typical Mistakes

Confusing SELCAL with CPDLC or ACARS—SELCAL only alerts the crew, it does not transmit text or data.

Forgetting that SELCAL checks must be re-established after every frequency change.

Assuming SELCAL replaces all radio monitoring—pilots must still monitor for emergencies or when SELCAL is inoperative.

Believing SELCAL codes are numbers; they are always four letters.

Thinking SELCAL is used for air-to-air communication—it is strictly air-to-ground.

Test yourself

Example Exam Questions

Question 2Easy

Which phrase should a pilot use to request a check of the SELCAL system?

Question 3Medium

What action must a pilot take after changing frequency when using SELCAL?

Still not fully confident?

Deepen your knowledge with an AI tutor built specifically for EASA ATPL students.

Built from thousands of ATPL knowledge references, real exam references and official learning objectives.

Open Avi AI Tutor

Keep going

Related Concepts

Still have questions?

Ask questions in plain English and get exam-focused explanations from an AI tutor built specifically for EASA ATPL students.

Open Avi AI