The national air traffic control centre is still suffering a catalogue of problems almost a year after opening, according to a member of staff there.

A senior air traffic controller with nearly 40 years' experience told the BBC some of the problems at Swanwick in Hampshire were "potentially catastrophic".

The controller, who did not want to be named, told Radio 4's Today programme there had been occasions when radio communications cut out erratically.

One or more of these [faults] coming together could actually lead to some very, very serious problems Karl Schneider, Computer Weekly

But the head of the air traffic control service dismissed the claims and said the system was safe "in aviation terms".

The unnamed controller told the Today programme: "There have been several instances when the technical controller suddenly isn't able to hear transmissions from aircraft.

"Potentially it's dangerous, of course, because he will assume instructions he's given are not being followed... where decisions have to be made very quickly, this obviously can cause some confusion."

'Open reporting'

Controllers' screens were not clear enough to be safe, he said.

The screens had green labels for planes the staff were working with, and white labels called "background tracks" for planes the operator was not talking to.

The controller said these background tracks were a "serious" problem, because they were not bright enough to be seen clearly.

We have exceeded our safety targets this year since the opening of Swanwick Richard Everitt, NATS

"A controller descending or climbing an aircraft with a green label may not see the white label in confliction with it.

"There's not enough contrast in my opinion to safely operate these screens."

Richard Everitt, chief executive of National Air Traffic Control Services said it was it was "not the case" that people were being told not to make entries into the accident book".

He said the service had an "open reporting culture" which it fostered.

He added: "We have exceeded our safety targets this year since the opening of Swanwick."

The controller also had health and safety concerns.

'Very, very serious'

"It has been reported to me by one or two staff members that they've come under a great deal of pressure from superiors not to make entries into the accident book.

"The argument usually goes: 'You've already made one entry a few days ago, there's no need to keep writing it every day'.

"The staff have said to me: 'If I'm having a headache everyday, I really want to write it in the book every day'."

RECENT PROBLEMS

Radios cutting out Screens too dim to read properly Downplaying of health and safety issues Source: Air traffic controller on Today

Swanwick opened in January at the cost of �623m, to replace a centre in West Drayton, near Heathrow.

It was supposed to enable controllers to look after more planes - thus in effect expanding UK airspace.

But according to Computer Weekly editor Karl Schneider that has not happened.

Airspace 'handed over'

"Now actually what we've found is we've had record delays for airlines and passengers; screens so unclear they break health and safety regulations and a catalogue of other problems.

"The fear is that one or more of these coming together could actually lead to some very, very serious problems."

The controller said the various problems suffered by Swanwick meant some of the work was having to be farmed out elsewhere.

Some work was going to a Scottish office, which had an "older but slightly more efficient" computer system, and some back to West Drayton - which he said was more efficient staffing-wise.

"Part of British airspace in fact is being given over to the controllers at Amsterdam - again to make life easier for the control staff at Swanwick."