THE WORLD'S LEADING charter operator, Britannia Airways, is to be the first airline to equip its fleet with the Contran system designed to prevent simultaneous radio transmissions. The UK carrier will fit its 32-strong Boeing 757/767 fleet during the northern winter of 1996/7.

At the same time, British Aerospace Systems & Equipment has emerged as the new vendor of the airborne version of the Contran. A previous agreement between Contran inventor Nigel Corrigan and Penny & Giles has lapsed.

Contran works by listening for conflicting transmissions, as a pilot presses the transmit button and inhibiting the transmission, if necessary. A ground-based version for air traffic control (ATC) is available.

Britannia has run a single-aircraft trial of the system for two years and is convinced of its worth, even though the benefits are limited unless other carriers also equip.

Britannia technical development pilot John McMillan says: "A typical scenario that Contran frees us from is when ATC issues an instruction with a clipped call-sign, and you confuse the three numbers of the call-sign with [those of] someone else."

This "...happens quite routinely", he says, adding: "When two aircraft reply to the transmission, if we are the second one, then we know that there is a possible confusion and we can sort it out. Without Contran, then we will reply almost simultaneously, and ATC will reply to one or the other."

Source: Flight International