Squawk in aviation refers to the communication between a plane’s transponder and air traffic control.

Squawking is the act of sending a 4-digit squawk code via a transponder to an air traffic controller.

Squawking is an effective way for airplanes to alert ATC and other planes of emergencies, including an airplane hijacking and onboard communication failure.

In aviation, the term squawk only refers to communication, while the term transponder enables this communication.

Pilots are provided with squawk codes before each flight. 

Most countries have their own unique squawk codes.

What does Squawk Mean in Aviation?

Squawk in aviation means any communication made via a plane’s transponder or any radio equipment designated for communicating with air traffic control (ATC).

Squawk codes are a way of discreetly and efficiently communicating something about an aircraft, such as its location, or to send an emergency alert. 

The term squawk code is often used synonymously with transponder codes.

But some only use squawk to refer to emergency transponder codes or the International Civil Aviation Organization (ICAO) codes. 

What does Squawking Mean?

Squawking is the act of a plane communicating with ATC on the ground by transmitting a code via a transponder or other radio equipment.

Squawking is a simple and effective way for airplanes to transmit important information, especially related to safety. 

How Do Squawk Codes Work?

A pilot is provided squawk codes before a flight and instructed to set their transponder according to those codes.

ATC is able to track the aircraft after the pilot sets their transponder to that code.

ATC sees the flight’s squawk code on radar, and the squawk code can even refer to the plane’s specific flight path. 

ATC will use this information to help the pilot avoid traffic, help the pilot out if the plane gets lost, and keep the plane from entering restricted airspace.

The plane’s transponder would run throughout the entire flight to let the ATC monitor it. 

During an emergency, the pilot inputs the relevant code, which will squawk it to the ATC and nearby planes to alert them.

ATC would then provide the pilot with instructions on how to proceed. 

Do All Planes have Transponders?

The vast majority of planes have transponders.

Some small planes aren’t required to have transponders to operate in certain airspace or at specific altitudes.

For example, the FAA requires aircraft to have a Mode-S transponder-based ADS-B transmitter to fly at 18,000 feet. 

Examples of Squawk Codes

These three emergency squawk codes have been reserved to quickly inform ATC of the type of emergency a plane is experiencing. 

7500 – Hijacking

Squawk code 7500 sends a silent alert to ATC to alert them of a hijacking.

In response, emergency support from security services and air traffic control will be provided. 

This code sends a silent alarm to prevent the hijacker from learning about it. 

7600 – Lost Radio/Communications 

A pilot can input squawk code 7600 if their radio or communications systems stop working, though the transponder will continue to work.

Upon squawking this code, ATC will learn that the pilot cannot communicate with them due to a communication systems problem. 

7700 – General Emergency (Engine Failure, Medical Emergencies, etc.)

A pilot can input squawk code 7700 for all emergencies other than hijacking and malfunctioning communication systems.

Emergencies that qualify for the 7700 squawk code include the following;

  • Pressurization problems 
  • Engine failure 
  • Fire 
  • Flight control problems 
  • Landing gear problems 
  • Fuel emergencies

How Many Squawk Codes Are There?

There are 4,096 squawk codes.

Every country has its own allocated transponder codes, with few being shared across borders.

The International Civil Aviation Organization (ICAO) has 6 transponder codes.

The squawk codes that a pilot uses for a flight are given to them by air traffic control before the flight. 

When Was the First Squawk Code Used?

The first squawk codes were used during World War II.

Aircraft during World War II used a system called IFF (Identification Friend or Foe).

This system worked because a device on the ground would query an airplane to identify itself. 

The pilots referred to the onboard device that relayed the queries to them as a ‘parrot.’

The response was, therefore, a ‘squawk’ from the ground. 

What Is the Difference Between Squawk Code and Transponder Code?

Some people use the terms squawk code and transponder code interchangeably, while others only refer to emergency codes or the International Civil Aviation Organization (ICAO)’s codes as squawk codes. 

Squawk refers to the name of the communication between an airplane transponder and the ATC.

The transponder is the device that’s used to complete this communication.

In conclusion:

  • Squawk refers to the communication between an airplane’s transponder and an air traffic controller (ATC).
  • Squawking is an effective way for airplanes to communicate with other planes and ATC during emergency situations, like a hijacking.
  • Pilots transmit squawk codes by inputting a 4-digit code into the plane’s transponder. The transponder then relays the code to nearby aircraft or the ATC.
  • The modern squawking system developed from the Identification Friend or Foe (IFF) system that was first used during the second world war.
  • Some people use the terms squawk codes and transponder codes interchangeably.
  • But others only refer to emergency transponder codes or the transponder codes of the International Civil Aviation Organization (ICAO) as squawk codes.