Air system failure unprecedented
An unprecedented systems failure at the UK's national air traffic control centre involving computer code written a quarter of a century ago was responsible for widespread disruption at British airports, it has emerged.
Richard Deakin, chief executive of Nats, the company responsible for controlling British airspace, said the software glitch was "buried" among millions of lines of code at the site in Swanwick, Hampshire.
Passengers faced travel chaos as dozens of flights at airports around the country were disrupted or cancelled yesterday and early today.
About 40 flights at Heathrow were cancelled before 9.30am, after which the airport said normal service was resumed.
Transport Secretary Patrick McLoughlin described the disruption as unacceptable, and MP Louise Ellman, chairwoman of the Transport Committee, said Mr McLoughlin will be asked about the incident when he appears before the panel on Monday.
Mr Deakin, who according to the Sunday Times earns more than £1 million after receiving a 45% pay rise this year, said the software glitch was "buried" among millions of lines of code.
He told the BBC: "The problem was when we had additional terminals brought into use and we had a software problem that we haven't seen before which resulted in the computer which looks after the flight plans effectively going off line.
"The good news is of course that everything came back online 45 minutes later, the back-up plans went into action as they should have done, so everything performed normally there, the skies were kept safe.
"Unfortunately there was reduced capacity and I would just like to reiterate our apology that we have made to passengers and indeed to airlines and airport customers for the disruption that was caused.
"But I think the key message is that the skies were kept absolutely safe during that 45 minutes of problems that we experienced at Swanwick."
Mr Deakin added that it was a "very unusual event" which had not occurred before.
He said: "The challenge is that we have around 50 different systems at Swanwick and around four million lines of code. This particular glitch was buried in one of those four million lines of code."
Mr Deakin said the problem had been "effectively rectified", and gave assurances that it would not reoccur.
He conceded that some of their systems were "fairly elderly", adding: "The system we had a problem with last night has code written in the early '90s."
Nats is investing a "huge amount" in new technology, Mr Deakin said, with £575 million set to be spent over the next five years to move towards more resilient, internet-based systems.
Nats said it understood the problem was connected to a number of workstations "in a certain state" combined with the number of "air space sectors" open.
Officials restricted air space in response to the issue, leaving flights at some airports grounded yesterday.
Nats declared that its systems were back to full operational capacity last night but a knock-on effect has been seen at airports today.
Gatwick airport said there had been 16 cancellations and seven diversions of inbound flights yesterday but said the airport was running normally today.
Airports as far north as Aberdeen and Edinburgh were also affected by the computer problem. Other airports that reported delays yesterday afternoon included Manchester, Stansted and Luton.