THE chief executive of the Hampshire based National Air Traffic Services has apologised to passengers for the chaos at airports after a computer glitch caused dozens of flights to be grounded.

Services heading into Britain were suspended for two hours after staff at the £623m Swanwick air traffic control centre were forced to abandon their computer system.

Controllers had to guide aircraft manually after computer problems hit NATS's West Drayton site, near Heathrow, which processes information for Swanwick.

The computer glitch at West Drayton came after a test of the system.

NATS said the system was operational again by 7am but passengers faced a morning of travel misery.

Flights from Southampton International Airport were disrupted for several hours yesterday morning.

An airport spokeswoman estimated around 350 people flying out had been affected. The first departure for Malaga, Spain, due out at 6.30am did not take off until 7.21am and other flights were also delayed for about an hour and a half.

Incoming flights were delayed by up to one hour 35 minutes and that also caused a knock-on effect to scheduled departures.

Poole based businessmen Chris Jeapes and Vernon Lees were due to fly out at 9.10am for Newcastle.

But 20 minutes before their flight was due to leave they were facing an "indefinite" delay.

Mr Jeapes said: "This will cause us problems. We support a major NHS trust in Northumbria and supply fairly critical telephone services for them.

"We have issues with the projects and the business in general which we need to go up there and resolve. It was scheduled for a day event."

But by yesterday afternoon Southampton was reporting that everything was back on schedule with only two flights, to Scotland, which had to be combined.

"It all returned to normal quite swiftly, which was good," said an airport spokeswoman.

But the problem with the West Drayton system said to be about 30 years old and not due to be replaced until 2010-11, brought an apology to passengers from NATS chief executive Richard Everitt, who insisted that the system had to be upgraded.

He said: "We are doing a major upgrade later in the year. Morale is not low at the centre.

"I would like to apologise to all passengers and tell them that we are doing our best to minimise the disruption to them."

The glitch centred on the flight data processing system which gives information to controllers at both West Drayton and the Swanwick centre, which opened in January 2002, more than six years behind schedule and £200m over budget.

With the computer not working properly, the flight information had to be prepared manually on a back-up system.