An Overview of the Traffic Alert & Collision Avoidance System (TCAS)

According to the Federal Aviation Administration (FAA), there are about 5,400 aircraft in the sky at peak operational times on any given day in the United States. With so many planes in the sky flying along similar flight paths, the Traffic Alert and Collision Avoidance System (TCAS) employed is indispensable for avoiding catastrophe. As a computerized avionic system, the TCAS monitors the airspace around an aircraft regardless of ground air traffic control, and warns pilots of the presence of other aircraft that could present a collision threat in flight. As such, it can be very helpful for pilots to understand the role of this essential system.

What Is TCAS?

TCAS tracking monitors the distance, altitude, and detection parameters for each aircraft that installs a transponder capable of responding to system queries. The system tracks the airspace around the aircraft and will alert the pilot of the presence of other aircraft which pose a risk of collision. These systems work separately from ground traffic control to ensure that they catch the unexpected. However, this system is not foolproof; thus, pilots must perform a visual assessment to confirm the accuracy of the alert.

A Brief History

Research on collision prevention systems began in the 1950s and continues to develop thanks to the collaboration between the airline industry and the Air Transport Association of America. However, it was only around the mid-1970s that research shifted its focus to the use of aircraft transponder signals. Using transponder signals allows collision avoidance, regardless of ground air traffic control. By 1981, the FAA made the decision to implement a concept of aircraft collision prevention, and this became known as the Traffic Alert and Collision Avoidance System (TCAS).

Soon after, prototypes of the TCAS II were installed on two Piedmont Boeing 727 aircraft and were flown on regular scheduled flights. The first tests proved useful for providing information on the frequency and circumstances of collision warnings that allowed the TCAS to be certified in 1986, and then approved for operational assessment in 1987. Then, the crash of Aeroméxico Flight 498 on August 31, 1986 further expedited the development and implementation of the TCAS on aircraft.

How does the TCAS Work?

The TCAS issues three main types of alerts: traffic advisory (TA), resolution advisory (RA), and a clear of conflict alert. When a TA is issued, pilots are expected to carry out a visual search of the traffic causing the warning, and maintain visual separation from any traffic they observe. When an RA is issued, pilots must respond to it immediately unless it would jeopardize the safe operation of the flight. Resolution notices advise each pilot at risk for collision to climb or descend to ensure ample distance between aircraft. Additionally, planes must have a much higher separation at high altitudes, so thread detection sensitivity increases with altitude. Conversely, when flying low you can maintain a shorter distance, as is usually the case near the airport during departure and landing. Lastly, “clear of conflict” is a message that conveys that there are no collision risks to be aware of and the pilot may proceed as normal.


Traffic Alert & Collision Avoidance System are vital and mandatory parts of commercial aviation that have been helping prevent mid-air collisions for decades. With an inventory of over 2 billion new, used, obsolete, and hard-to-find components in our inventory, Limitless Aerospace is here to assist you with finding all the aviation products that you require, including durable IT hardware parts. As a premium aircraft parts distributor, we provide thorough quality evaluation for all our items, along with expedited shipping to meet our customers’ strict operational requirements. When you need high-caliber items, including thermocouples, Limitless Aerospace is here to assist you with all that you require.


October 6, 2022
August 18, 2022

Recent Twitter Posts

Semiconductor's Certifications and Memberships
Thank You for Visiting Limitless Aerospace.

Don’t forget That If You’d Ever Like a Quote for Parts Within 15 Minutes or Less, You Can Fill out the Instant RFQ form On this Website’S Homepage.

Request for Quote

We use cookies to ensure that we give you the best experience on our website. If you continue to use this site we will assume that you are happy with it.