There have been many advances in the Air Traffic Control (ATC) system since it was started, but none as important as the radar. When radar was first presented, all that could be seen on the radar scope was a "blip." This blip was cause by anything in the path of the radar waves such as an airplane. Tops of trees, towers, or even some types of birds could bee seen as blips. To be sure that the controller was talking to the right aircraft, he would ask the pilot to do a series of turns. Once the correct blip was identified, the controller would then place a transparent plastic tab with the aircrafts identity by hand on the scope. This tab was nicknamed the "shrimp boat" because of its shape (Hopkin, 25). After the blip changed positions the shrimp boat had to be moved by hand to the new location of the blip. Since these tabs had to be placed on the scope, the scopes had to be positioned in a horizontal fashion. This made it hard to see the top of the scope.

The human workload was greatly reduced when secondary surveillance radar replaced the out of date primary radar. Secondary radar depicted the position, heading, relative speed, and aircraf

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Some common words found in the essay are:
Control ATC, Radio Transmissions, Marking Keeping, CGDis Figure, human factors, air traffic control, air traffic, flight strips, traffic control, radar scope, flight strip, Human Factors, shrimp boat, shrimp boats, handed controllers, curser movement devices, secondary radar,
Approximate Word count = 1406
Approximate Pages = 6 (250 words per page double spaced)