THE US FEDERAL Aviation Administration is to begin trials of a system designed to prevent simultaneous air/ground voice-communication transmissions. UK purchasers of the system, however, are complaining about the UK Civil Aviation Authority's attitude to it.

The FAA will shortly receive four examples of the ground version, and two of the airborne versions of the UK-produced Contran system.

Contran prevents controllers and pilots unintentionally transmitting simultaneously, by electronically "listening" for signals. The airborne and ground elements work independently and bring separate safety benefits.

The FAA Technical Center at Atlantic City, New Jersey, is taking the equipment for trial work primarily related to the need to solve difficulties with its precision runway monitor (Flight International, 8-14 February), but also to explore Contran's inherent advantages.

Two UK airports - East Midlands and Bournemouth - have bought the system but more than six months later, Bournemouth has only just received CAA engineering approval. East Midlands says that it is "extremely annoyed".

In May 1993, the CAA issued an Aeronautical Information Circular noting that minimum operational-performance specifications for equipment of Contran's generic type had been published and that, in trials, such devices had "...proved to be extremely effective".

Source: Flight International