Understanding Squawking in Aviation: A Comprehensive Guide

Aviation is a complex and interconnected system, where every detail matters for maintaining safety and efficiency. One crucial aspect of this system is the process of squawking. In this guide, we will explore the key points about squawking, including its history, current usage, and importance in aviation.

What is Squawking?

In aviation, squawking refers to the process of entering a specific four-digit code into an aircraft's transponder. This code, also known as a squawk code, is essential for communication and identification purposes. Squawking is a term derived from the British World War II technology, PARROTT (now known as IFF, or Identification Friend or Foe), which was used to distinguish friendly aircraft from enemy ones.

Transponder Codes

Each aircraft is assigned a unique four-digit code that serves as a squawk code. In the United States, for example, Visual Flight Rules (VFR) flights typically use the squawk code 1200. These codes are utilized for several purposes:

Identification: ATC uses these codes to identify and track aircraft on radar. Communication: Pilots can be instructed to change their squawk codes in response to various situations, such as entering controlled airspace or handling specific ATC instructions.

Transponder Modes

Aircraft transponders operate in different modes, each providing varying levels of information:

Mode A, C, and S

Mode A: Provides only the squawk code. Mode C: Provides altitude information along with the squawk code. Mode S: Offers additional data, allowing for more detailed communication with ATC.

Emergency Codes

There are specific squawk codes designed for emergencies:

7500: Hijacking 7600: Communication failure 7700: General emergency

VFR and IFR Conditions

When dealing with different flying conditions:

VFR (Visual Flight Rules): Pilots typically squawk 1200 under VFR conditions. IFR (Instrument Flight Rules): Pilots use codes assigned by ATC.

The History of Squawking

Historically, squawking originated during World War II, when the British developed a system using RADAR and secondary transmitters carried by aircraft. This invention, called PARROTT, allowed RADAR operators to distinguish friendly aircraft from enemy ones by instructing pilots to squawk their PARROTT (now known as IFF, or Identification Friend or Foe).

Over the years, the system has evolved significantly, allowing for more than one code. Today, the transponders use a combination of digits (0-7) in four rows, offering a total of 4096 (8x8x8x8) different selective codes.

Controller Instructions

Control tower operators often instruct pilots to:
- Set a specific code in their IFF transponder
- Stop squawking (speak to radar) for a period

These instructions are commonly followed by a four-digit code or a word like SQUAWK IDENT, which allows the pilot to select that number or feature on their equipment.

Importance of Squawking

Squawking is a vital component of safe and efficient air traffic management. It allows ATC to monitor and communicate with aircraft effectively, enhancing overall safety and coordination in the airspace. This system is essential for maintaining the high standards of aviation safety and order that we see today.