Heavy Traffic

The U.S. air lanes are getting too thick with planes. In the near future, most air traffic experts agree, something new will be needed to keep them from getting in each other's way. Recently the Air Transport Association of America described an ideal system for instrument designers to shoot at. It amounted to the sort of block system that railroads use.

Airliners now follow radio beams from airport to airport. By keeping on the proper side of the beam they can avoid collisions. But the beam system provides only a limited number of "lanes." It gives traffic operators little exact information about airplanes in flight at different altitudes, and insufficient control over them.

Keep to the Lane. A.T.A. foresees a system of many lanes, like a multitracked railroad, marked out in the air by ground radio stations 90 or more miles apart. Each airplane will be assigned a lane to its destination; automatic instruments in the plane will tell the pilot if he is keeping on it (see diagram).

The lanes will be marked into blocks.

When an airplane nears the end of a block, instruments will tell the pilot whether the next block is empty. If there is another plane ahead, he will circle around until the block is clear.

Radio apparatus on the ground will keep track of every plane. If one falls badly behind schedule, it will be ordered aside into an unoccupied lane before the planes behind it begin treading on its tail.

How soon could such a system be put in operation? The Civil Aeronautics Administration is already installing "Omnidirectional Ranges" to mark out the lanes. The chief component now lacking is a satisfactory instrument for marking out the blocks. A.T.A. says that the electronic principles to perform this service are already known. It hopes that its idealized blueprint will stimulate designers to put them to practical work.

Follow the Track. A block system for the air's great open spaces will help aviation's most critical ill (congestion around busy airports, especially in thick weather) by spacing arriving planes. Two different methods are being tested to get them safely down out of the crowded air. One method: GCA (Ground Controlled Approach) watches the plane with radar while operators on the ground "talk" it down through the soup. The other: ILS (Instrument Landing System) guides the plane down a slanting radio beam.

S. Young White, a New York inventor with 185 patents to his credit, recently proposed a third method which he calls

MAU (Maximum Airport Utilization). The White method is something like the traffic system used in New York subways.

The basic device of MAU: radio transmitters which shoot thin "fans" of radio energy into the air. They are arranged in pairs so that their fans intersect at a predetermined altitude. Long lines of these intersections form tracks leading down to the airport. The pilot of an approaching plane "latches on" to the end of a track, 40 miles out. Then automatic instruments take over, keep him on the track of intersections until he is practically on the ground. Receiving sets spotted along the track flash lights in the control room, tell ground operators just where the plane is.

MAU has not been tested in actual operation. Inventor White admits that it will be inflexible, and hard on poorly equipped private planes. But this he regards as inevitable: "Nobody runs a handcar down the New York subway."

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