Air Transport

Infringements of UK-controlled or restricted airspace, mainly by general aviation aircraft, have increased by about 20% during the last year, according to the Civil Aviation Authority, with the majority of the infringements occuring within the "complex airspace structure" in southern England.

There were 633 reported infringements in 2006 with an average of five occurring every three days throughout the year, the CAA says.

The majority of the incidents involved incursion into controlled airspace - primarily control zones serving airports, control areas and airways.

There is a clear cyclical pattern to when they occur, the authority adds. "Peaks are traditionally reached during the summer months - good visual flight rules conditions encouraging more pilots to fly, and the sheer number alone increasing the probability of infringement - with troughs emerging with the onset of autumn and winter.

The arrival of spring brings with it a steady monthly rise in reported infringements, leading again to the annual summer peak."

The CAA admits that the statistics may be influenced by more rigorous monitoring and aggressive reporting regimes introduced by UK air navigation service provider NATS two years ago, to reduce the risks posed by infringements and concedes that the the number attributed to general aviation (GA) pilots must be considered within the context of the number of GA pilots and aircraft and the number of flight hours flown by them.

"Conversely a reluctance by many air traffic control units to formally report infringements can hide true accuracy levels and patterns," says the CAA. "We are not reaching all the people out there and we do not have the totality of the picture."

NATS and the CAA says around 75% of GA aircraft in the UK are transponder-equipped and GA pilots "should make better use of this equipment".

Late last year NATS introduced a new procedure that allocates transponder codes to aircraft receiving an air traffic service from "London Information".

The unique four-digit code allocated can be seen by other radar controllers and tells them that the aircraft in question is currently on the London Information frequency.

This enables controllers to pass any relevant safety information to the aircraft, such as warnings of impending airspace infringements or navigational advice and assistance if an infringement has occurred.

NATS says: "Since the procedure was introduced eleven potential airspace infringements have been prevented and seven actual airspace infringements have been more speedily resolved."

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