Air Transport World

One collision avoidance system ready, another shows promise. (Traffic Alert and Collision Avoidance System)

The skies are becoming more crowded. FAA recently forecasted that takeoff and landings at U.S. tower-equipped airports in 1995 will total 95.6 million operations, a 67.1% increase over 1983 levels. The primary collision avoidance system is the ground-based air traffice control system. The only real backup to the ATC system has been the sharp and hopefully watchful eyes of the flight crew.

Both the ATC system and its backup use large amounts of humanity to process information. Although thousands of years have been devoted to human software development (education), this element is known to suffer widely random functional degradations at critical times, occasionally resulting in accidents. Government agencies and airlines since the mid-1950s have been looking for a mechanical device to insert into the backup chain to increase the guard against mid-air collisions. After many false starts and a few nearly completed programs that ended up bearing rotten fruit, it looks as if a radar beaconbased system called the Traffic Alert and Collision Avoidance System (TCAS) is going to be that long-sought mechanical backup.

In fact, the basic Minimum TCAS II essentially has been ready for use since late last year when Radio Technical Commission for Aeronautics completed its work on the system's Minimum Operational Performance Standards (MOPS)--a 600-page tome. Airlines can order this equipment right now, but no one has, perhaps fearing to be the first to field a brand new system. Of course, without orders manufacturers have not committed to production. This reluctance on the part of carriers is forcing FAA to go a step beyond its usual stopping point in the development of a safety system. It has plans to partially fund a Limited Implementation Program (LIP) that, at this writing, promises to put TCAS into seven aircraft flown by three U.S. airlines.

While this is going on FAA is continuing to work on an Enhanced TCAS II that will provide pilots with directions for horizontal collision avoidance maneuvers (left/right) in addition to the vertical (climb/descent) maneuvers for escape supplies by Minimum TCAS II. …

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