Landing system on USS Enterprise

If I'm right, it's the glide slope transmitter. It sends a beam in specific frequencys to the landing a/c. With a reciever and indicator in the plane, the pilot will know if he is high or low when they are a ways from the carrier and do not see the deck ('clara' is called when the pilot does not see ship) This technology is constantly changing with automated landing systems to land the a/c with no input from the pilot. You may consider choosing a "time frame" to model to help choose the color you might use as they are probably changing those box's constantly to keep up.