For as long as I can remember, I have been attracted to the world of aviation. I was exposed to the airline business early in life, and have been very fortunate to spend my career with my company of choice: American Airlines. Today, as an executive and a licensed pilot, I continue to be fascinated by both the economic and technical challenges inherent in moving hundreds of aircraft from place to place, all over the world, every day.
Commercial aviation has a language all its own, and sometimes it seems that half that language is made up of acronyms. With a little effort, I could probably fill the entire space allotted to this column with nothing but airline acronyms. But that wouldn’t make very interesting reading for most of you, so I’d like to devote this month’s column to just one very important acronym — TCAS, which stands for Traffic Alert and Collision Avoidance System.
TCAS is one of the many important tools our pilots use to ensure the safety of every American Airlines and American Eagle flight. It combines onboard transmitters, called transponders, which signal the airplane’s presence to other aircraft in its vicinity, and powerful onboard computers that recognize the TCAS messages sent by other airplanes. If any aircraft are nearby, TCAS alerts the pilots, who can then initiate appropriate course or altitude adjustments necessary to prevent the possibility of a midair collision.
Virtually all commercial passenger airplanes flown by U.S. carriers are equipped with TCAS. As a result, at any one time, aircraft in a given vicinity are, in effect, talking to each other — sharing information about altitude, speed, direction, and whether they are climbing or descending.
In the cockpit, an onboard computer synthesizes all the information being received from other airplanes and displays it on a computer screen for the pilots, who are able to see all the traffic within a designated perimeter. Pilots can set the screen to show a 5-mile, 10-mile, 20-mile, or 40-mile area around them. Typically, they will look at the 40-mile picture during flight, then reset it for a tighter snapshot as they get closer to landing. On the screen, every airplane within the chosen perimeter appears as a white diamond.
Within that larger picture, the computer focuses on an envelope that is designated as the airplane’s protected airspace. The envelope is oval in shape and covers an area 1,200 feet above and below the airplane and a variable distance in front and behind. Should another airplane come close to that envelope, the computer lets the pilots know that their protected airspace will be penetrated in 40 seconds unless evasive action is taken. In a loud voice, the computer says “Traffic, Traffic,” and at that time the white diamond representing the approaching aircraft becomes an amber circle, with data showing its altitude and whether it’s headed up or down.
If an aircraft were to get even closer, within 25 seconds of the protected airspace, the computer would issue another warning, the amber circle representing that plane would become a bright red square, and the computer’s voice would tell the pilots to climb, descend, or take one of a number of other possible actions to avoid conflict, as appropriate. Simultaneously, the plane making the incursion would receive instructions directing it to take actions — coordinated with the actions of the first aircraft — to increase separation between the two, and thereby further minimize the risk of collision.
As you would expect, equipping our entire fleet with TCAS is an expensive proposition. Over the years, we have spent hundreds of millions of dollars to install this advanced technology on every American Airlines and American Eagle airplane, and to train every one of our pilots to use the system. Expensive as it is, it’s an investment in safety that we’re happy to make on behalf of our customers and our employees.
I want to thank you for flying with us. I know I speak for every member of our team when I say we are working very hard to make sure your travels with us are always safe, comfortable, and enjoyable.
GERARD J. ARPEY
President & CEO