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In the Boston-Washington air corridor alone, he said, there were between five and nine reported "incidents" per week—situations in which the separation between two aircraft was less than the FAA minimum. If all incidents were logged, Lyman said, there would be from 20 to 25 per week; many go unreported because controllers do not want to take time off from their work or get themselves or flight crews in trouble.
Need for Expansion. Calling the union's charges "exaggerated," the FAA pointed out that there were no mid-air collisions of airliners in 1966 and that most of the 25 mid-air collisions involving private aircraft occurred near small fields that were not under the agency's control. The number of reported near misses declined from 565 in 1965 to 463 in 1966, despite a 19% increase in flight operations. But the growing numbers and speeds of aircraft clearly call for more sophisticated devices to ensure safety in the skies.
Many aviation experts believe that an essential device for preventing high-speed collisions is a collision avoidance system (CAS) that warns the pilot early enough for him to take corrective measures. FAA authorities are hopeful that a CAS device acceptable for airline use may evolve from a system devised by the McDonnell Co. (see cover story) called EROS (for Eliminate Range Zero System). It has already been successfully used by McDonnell in high-altitude testing areas near St. Louis. When an EROS-equipped aircraft is on a collision course with another plane, a beeping sound is produced in the pilot's earphones. Glancing at his instrument panel, the pilot sees a lighted arrow pointed either up or down, in the direction that EROS calculates he should take to avoid a collision. EROS provides a 60-second advance warning at closing speeds as high as 3,000 m.p.h., adequate for even supersonic transports.
Category II Landings. Equally important for effective air-traffic control is the ability of aircraft to land at their destination in any kind of weather. "If aviation is to reach its full potential," says FAA Deputy Administrator David Thomas, "we shall need to have in daily operation a true, dependable, all-weather landing system. One socked-in airport, even today, disrupts an entire area. Think of the problems that would arise from a zero ceiling and visibility at JFK in the era of 500-passenger planes and SSTs."
Using automatic systems, several U.S. airlines have already been cleared for "Category II" landings at some airports. These permit properly equipped planes to be guided electronically and automatically toward a landing when the ceiling is as low as 100 ft. and visibility is as little as 1,200 ft. At an altitude of 100 ft., the pilot takes over and completes the landing if he can see the lights and markings—or he uses full throttle to climb away if he cannot see them. The FAA is also considering such aids to blind-landing systems as Bendix Microvision, which uses microwave radio signals beamed to the plane by ground transmitters from the sides of the landing strips. The signals form an image of the runway on a display in front of the pilot, enabling him to find it in zero visibility.