Today a pilot is totally dependent on what the air traffic controller on the ground tells

Today a pilot is totally dependent on what the air traffic controller on the ground tells him. He can"t see enough to be safe. Flight watch is an instrument intended to help him.

On a screen in front of the pilot, there will be a map of the【21】around the plane. The pilot"s own【22】level or height and his own plane at the center of the【23】will show up. On the map any other planes in the airspace will【24】as spots of light with "tails" showing the direction of their light. The flight watch map is【25】for the other planes are not shown at their true【26】, but at their distances away in flying time. This【27】the problem of fast planes being too far away to be seen【28】likely to make contact in seconds and【29】planes that are close enough to be seen but so slow that there"s no chance of【30】for, say, ten minutes.

The pilot will be able to see on the screen whether another plane"s course conflicts with【31】. The screen will show him the flight number of the other plane, so he can contact air traffic control and ask them about the other plane’s course. Then he can take【32】action if necessary. The screen will show him whether his action puts him【33】from yet another aircraft.

Technically, the【34】will be quite complex. Computers will be necessary on the ground and【35】each aircraft to enable Flight watch to collect data about the plane courses and to calculate the distances between planes. But such small computers are now quite cheap, simple and reliable.

(36)

A．latitude

B．land

C．airspace

D．weather

请帮忙给出正确答案和分析，谢谢！