Thu 3 Jun 2004
National Air Traffic Services said flights were grounded so that controllers could prioritise on planes in the air, but safety was unaffected.
The air traffic control centre at West Drayton is now fully operational again and flights are resuming.
Many airports are advising people to check in as normal.
Nats’ Flight Data Processing System failed at around 0600BST for an hour.
Speaking to BBC News 24 Chief Executive Richard Everitt said the failure followed overnight testing of an upgrade to its Flight Data Processing System in West Drayton.
“This is a significant upgrade that we will be doing later in the year, we have to test that very thoroughly because safety is paramount.
“We will now investigate why there was this problem - clearly it was not an anticipated problem - a lot of work will be done today to understand why we had problems with this testing,” he said.
“What we did here was to ensure safety levels were maintained, we did that by taking the traffic right down, handling the arrivals while we sorted this problem out. ”
Mr Everitt said Nats was planning on spending over £1bn on upgrading its system over the next eight years.
He apologised to passengers and said Nats was working with airlines to minimise disruption.
‘Upgrade’
Speaking on BBC Radio 4’s Today programme, Transport Secretary Alistair Darling insisted Britain’s system compared favourably with other countries.
“We are putting the money in, it is making a difference.
“If you look at the delays caused by air traffic control failure they have come down dramatically over the last few years,” he added.
BBC transport correspondent Tom Symonds says the affected computer systems were not those that handle the separation of aircraft in the air.
He says the fault was in what is known as the host control system, a two-year-old computer system at West Drayton.
The system handles flight strips which are the basic details of flights coming in and out of the UK.
‘Uptight’
Spokesman for London’s Heathrow Airport, Mark Pearson, said: “There is serious disruption at Heathrow as a result of the air traffic control situation.
“There is an average of two hour delays on departures and restrictions on arrivals.”
He advised passengers to check with their airlines before leaving home.
Passengers Monica and Gerald Godfrey - waiting for a British Airways flight from Heathrow to Toronto - told BBC News Online their flight had been delayed by the problems.
The couple said they would have a cup of tea and relax after checking in.
“It depends on how long the delay is, we might get a little uptight,” Mrs Godfrey said.
Mr Godfrey added: “But at the end of the day there’s nothing we can do about it.
“As long as there is an aircraft and someone waiting for us at the other end we’ll be fine.”