What Is a “Squawk” Code and Why Do We Need Them?

Two pilots at work during departure of Dallas Fort Worth Airport in United States of America. The view from the flight deck with high workload the beginning night through the wind shield

The use of the word “SQUAWK” comes from the system’s origin in WORLD WAR II- IDENTIFICATION FRIEND OR FOE (IFF) system, which was named with the code “PARROT”. The PARROT check is generally done after the aircraft is airborne or while on the runway.

The primary goal of a squawk is to provide effective communication between ATC and the aircraft. Prior to departure all aircraft are given a specific squawk code and this code shows up on ATC screens and helps the ATC guide that particular A/C with their speed, altitude and more. These codes are not to be confused with “Conspicuity codes”, which are not necessarily unique to an A/C and are used to convey information to the ATC possibly when the A/C is not in radio contact with the ground. However, the squawk code is unique.

How does it work?

Photo Credits: aviatorshq.com

Basically these codes are a combination of numbers between zero and seven and do not exceed 4 digits. Hence that gives a multitude of combinations and permutations for the ATC to assign to the aircrafts. Interesting, isn’t it?

Pilots are required to enter these codes into their A/C transponders to communicate with the ground controllers. If the code is correctly entered, it will be shown on the ATC screens and the flight info will be correctly displayed. These 4 digit codes are very important, especially during take off and landings to ensure safe separation between aircrafts. Having the transponder switched off or inputting incorrect values can endanger flight safety.

The most commonly known squawk codes are those used for emergency purposes namely “SQUAWK 7500 – HIJACK” meaning the A/C has been hijacked and requires immediate assistance from ground support and law enforcement agencies, “SQUAWK 7600 – LOST COMMUNICATIONS” denoting the A/C has lost contact with the ground and would likely be guided using aviation light signals, “SQUAWK 7700 – “EMERGENCY” to communicate all emergencies onboard. With 7700 established, all nearby ATCs are also informed of the situation and the pilot can land the A/C in whichever way is deemed fit regardless of the rules with ground support on standby.

Squawk codes serve an important purpose in ensuring communication and safety between the A/C and ground. As the airspace around the world gets more and more congested, it becomes imperative that squawk codes are correctly followed by the ATC and flight crew.

Quick question: Squawk codes are also known as ”4096 CODE TRANSPONDERS”?. Comment your answer in the comments section below!


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