In the UK from 1 October 2009 all aircraft, except gliders, flying in class A to C controlled airspace will be required to carry and operate a mode S transponder.

From 6 April 2012 the rule will apply also to gliders. This is the final rule published by the UK Civil Aviation Authority following extensive consultation.

The CAA says that controllers will continue to be allowed to permit non-transponder equipped flights into the airspace "providing safety and efficiency levels can be assured".

But it adds that it will "amend the airspace change process to allow air traffic control service providers to apply for the introduction of compulsory transponder carriage in other specific volumes of airspace.

Mark Swan, CAA director of airspace policy, says: "This second phase of transponder regulations builds on the introduction of Mode S as the means of compliance for mandatory transponder carriage, which came into effect in March 2008.

"These changes further increase the use of technical interoperability to enhance safety. By adopting a measured approach, the increased use of transponders will enhance the culture of a collaborative approach to safety of flight by all users, without being unduly restrictive."

Swan adds: "Although gliders will now be included in the transponder carriage rules from 2012, we will be encouraging agreements between gliding organisations and air traffic control to permit gliders without transponders to access controlled airspace where conditions permit.

"Even though there is a general requirement for transponder carriage above FL100 in the UK, there will be no requirement for transponder carriage on gliders when operating in current active designated gliding areas. We will work with gliding organisations to consider additional areas from FL100 upwards by 2012."

Under existing transition arrangements associated with the previous expansion of mode S transponder carriage in UK airspace, operators of aircraft wishing to operate in mandatory transponder carriage airspace that are equipped with mode A/C transponders have until 31 March 2012 to complete the necessary upgrades to mode S.

Source: Flight International