Page last updated at 14:39 GMT, Friday, 26 September 2008 15:39 UK

Why Swanwick hit the headlines

By Rob Corp
BBC News

Swanwick ops room
Swanwick replaced the old West Drayton air traffic centre near Heathrow

It is possibly no surprise that when something goes wrong at the London Air Traffic Control Centre it inevitably hits the headlines.

The sheer volume of flights that originate and fly over the UK means there is no escaping the knock-ons when a fault occurs somewhere in the system.

On Thursday, delays and cancellations resulted when the computer that generates flight progress strips failed.

These provide controllers with information about the aircraft they are controlling in their designated bit of UK airspace including the radio call-sign, aircraft type, origin and destination.

Swanwick - generally speaking - has been operating since 2002 without a single serious safety incident
Richard Wright, Nats

While the system would normally generate a new strip relevant to each controller along the aircraft's route, this did not happen - and so details had to be entered manually.

This meant controllers were able to accept fewer aircraft, so flights waiting to depart had to be kept on the ground.

And while it may seem that the six-year-old air traffic facility at Swanwick in Hampshire has been plagued by problems ever since it opened, its operators are at pains to argue the reverse.

Software problems

Richard Wright of Nats - the partially-privatised company that provides air traffic control to commercial flights in the UK's airspace - admits that Swanwick had a "difficult birth".

The centre opened six years after its planned commissioning date, in January 2002.

Nats says that the extensive delay was mainly due to problems with the software it chose to power its systems.

The plan was for Nats to use a package that was being developed as part of a huge upgrade of the US air traffic control network.

Map of UK airspace
The London air traffic control centre at Swanwick, Hampshire, has two parts with different responsibilities:
The London Area Control Centre (LACC) is responsible for aircraft flying over England and Wales
The London Terminal Control Centre (LTCC) handles aircraft approaching and departing south-east England airports
There are two other domestic air traffic control centres in the UK
Manchester Area Control Centre handles aircraft flying up to 24,000ft in central and nothern England
Scottish Area Control Centre at Prestwick, Ayrshire is responsible for traffic in Scotland, Nothern Ireland parts of the North Sea and North Atlantic
The centres are run by National Air Traffic Services (Nats), which is part-owned by the government and a consortium of airlines

But this ran into problems - and the American project eventually collapsed. Richard Wright says this meant the software developers and Nats were left to continue alone.

Their role in picking up the pieces and bringing the software up to scratch "took much longer than planned," Mr Wright says.

But by 2002 the problems were fixed and the 632m Swanwick facility went live, controlling aircraft in the 200,000 square miles of airspace above England and Wales.

There have been issues since, but Nats maintains these have not caused serious problems.

"Swanwick - generally speaking - has been operating since 2002 without a single serious safety incident," says Mr Wright.

There have been problems with flight data processing in the past, though.

Mr Wright says this was down to problems with the former London air traffic control centre at West Drayton, near Heathrow airport.

"That has been rebuilt and re-hosted at Swanwick," Mr Wright says, and is "performing more reliably."

And of Thursday's problems, Mr Wright says they are still investigating the cause, but are assured it is the first time this particular issue has occurred - and that it is not a repeat of a previous problem.

Nats also points to last year's move of the London Terminal Control Centre from West Drayton to Swanwick as an unheralded example that the Hampshire facility is working well.

Now, aircraft arriving at, and departing from, Heathrow, Gatwick, Luton, Stansted and London City are under the control of a team sitting in a room 80 miles from the airport.

But with any change, inevitably there will be problems. Complaints have been raised on aviation internet forums that controllers' radios have become less clear since the move to Swanwick.

Departure screen
One system fails and the consequences become obvious

And there is also another upheaval due in 2009 and 2010, when controllers based at the Manchester and Scottish air traffic control centres move to new premises at Prestwick, Ayrshire.

The Scottish facility has had a similarly fraught genesis, with work being shelved after the terrorist attacks of September 2001.

Combining the intricate systems and technology that make up the UK's air traffic control system with the record numbers of commercial flights means that even if breakdowns are few and far between - when they do happen, the consequences are painfully obvious.

Air delays follow computer glitch
25 Sep 08 |  Northern Ireland
New air traffic system unveiled
07 Mar 07 |  Hampshire

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