Aircraft in controlled airspace, particularly those operating to airports with terminal control areas or zones, appear to be at greater risk than ever of collision with general aviation aircraft that stray into approach paths.

Eurocontrol has launched a questionnaire aimed at general aviation pilots - the aviation group most frequently involved - in a bid to get feedback on why so many airspace incursions occur.

Eurocontrol is working on this project with the European International Aircraft Owners and Pilots Association, but it has been worried about the problem for two years. In September 2006 infringements programme co-ordinator Alexander Krastev said: "Airspace infringements represent a severe threat to aviation safety, and the majority involve GA aircraft."

Infringements are usually the result of the pilots either not navigating accurately, or being ignorant of the presence of the restricted airspace they have strayed into.

The UK Civil Aviation Authority and Britain's main air navigation service provider NATS have been working together also for two years to quantify the issue and come up with a strategy for dealing with it.

Their study shows that GA airspace infringements are continuing to rise, having gone up by 20% in the last year alone. One of the tactics that NATS has employed is to reach out to the GA community bysetting up a website with video of actual airspace incursions, plus information aimed to help and interest light aircraft pilots.

The UK Civil Aviation Authority is keen to link the incursion issue with the fact that most GA aircraft that do not intend to use controlled airspace do not have Mode C transponders fitted.

But those that do, if their pilots are talking to the non-radar London Information service, can be allocated a squawk code that makes clear to radar controllers that the aircraft are on the Information frequency, so if radar sees a potential infringement the controller can warn the pilot through London Information.

The CAA says that since this procedure began in November 2006, 11 potential airspace infringements have been prevented and seven actual airspace infringements have been more speedily resolved.

Steve McKie, NATS safety division, explains: "In each of these cases a potentially serious incident has been averted by a radar controller spotting the risk and contacting the flight information service officer. They have then passed the information on to the pilot, enabling appropriate action to be taken to avoid the infringement or to clear controlled airspace in the safest manner."

Source: Flight International