Science: Hybrid VORTAC

One of Washington’s bitterest technical squabbles, the long rivalry between aircraft-guidance systems, reached a new phase last week. The Air Coordinating Committee announced a compromise plan that looks like a desperate attempt to offend no one. The plan recommends that both guidance systems, VOR (Very High Frequency Omnirange) and TACAN (Tactical Air Navigation) be “combined” under the hybrid name of VORTAC.

VOR, with “Distance Measuring Equipment” (DME), is the present civilian-guidance system. The Civil Aeronautics Administration has installed 480 of its ground stations, and will install 82 more during the current fiscal year at a cost of $86,000 a station. The stations tell a properly equipped airplane its direction and distance.

TACAN does much the same thing by a different electronic method. The Air Force and Navy prefer it chiefly because its ground stations are much smaller and work better from a ship or a cluttered land site. The military have installed their TACAN stations independently of the CAA. Twenty of them are already functioning, and 181 more are being set up. Chief civilian objection to TACAN is that it is new, untried and will force non-military aircraft to install costly new equipment.

Under the compromise proposed by the Air Coordinating Committee, the VOR stations will continue indefinitely to tell aircraft their direction. They will gradually stop, however, telling aircraft their distance. In many cases this service will conflict electronically with TACAN and so must be eliminated. Unless the Government foots the bill, civil-aircraft operators will eventually have to buy costly new electronics. Cost of a full VORTAC system: $4,100.

TACAN will be developed rapidly for military purposes. After it has been well tested by military use, its directional as well as its distance-measuring feature may be made available to civilians. Loudest objectors are owners of private aircraft, who feel that the military has loaded them with impossible electronic costs.