14 December 2014
Last updated at 03:18
The UK’s national air traffic control service Nats was reportedly warned four months ago that its plans on how to deal with technical failures were unclear.
The Independent says the Civil Aviation Authority criticised a report into a fault which grounded flights last year.
It follows Friday’s disruption to UK flights caused by a computer malfunction at Nats’s Swanwick centre.
Meanwhile, one MP has called for Nats’s chief executive to be docked his bonus.
The CAA’s warning came after Nats completed a report into a telephone failure at the Swanwick control room last December, which resulted in 300 cancelled flights.
It was one of a number of technical hitches to hit the partly-privatised service since the centre opened in 2002.
The report included an assessment of contingency and resilience plans. According to the Independent, the CAA, responded that its “themes on avoiding a recurrence” were a “good first step but lack detail and clarity”.
The CAA also asked for Nats to submit more detailed plans which would include a timescale for changes, and to explain who was to be accountable for fixing certain problems.
Friday’s disruption was caused by a single faulty line of code in one computer system, Nats chief executive Richard Deakin said on Saturday.
The failure caused problems at airports around the country – including at Heathrow and Gatwick, where departing flights were grounded for several hours. Thousands of passengers faced delays and cancellations.
Flights returned to normal on Saturday, although almost 40 were cancelled at Heathrow.
Mr Deakin told the BBC that the software problem was “buried” among millions of lines of computer code.
“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.”
“We haven’t seen that particular issue before,” he added.
He said Nats was spending an extra £575m over the next five years to bring its systems up to date, but warned that making improvements was a challenge as they had to be made “while the engine was still running”.
Swanwick air traffic control centre
Swanwick controls the 200,000 square miles of airspace above England and Wales, cost £623m to build, and employs about 1,300 controllers.
But the facility, which handles more than 5,000 flights every 24 hours, has had a troubled history.
It opened in 2002, six years after its planned commissioning date – a delay which Nats said was due to problems with the software used to power its systems.
Almost a year after it opened, a senior air traffic controller raised concerns with the BBC about health and safety standards and complications with radio communications – which he said cut out erratically.
Technical problems and computer faults hit flights in 2008 and again last summer. And, in December 2013, problems with the internal telephone system then caused further delays.
Labour MP Paul Flynn has called for Mr Deakin to be docked bonuses in his salary because of the disruption.
Mr Flynn, who sits on the public administration committee, told the Sunday Times: “I hope after the chaos, which was dreadful, though a rare event, he will have his bonus stripped from him.”
It has emerged that Mr Deakin had his pay package increase by more than 45% this year, to more than £1m, due to the maturing of an incentive scheme.
Mr Deakin has said part of his performance-related pay was linked to flight delays.
“The reason why the pay went up was because the first of the long term incentive plans started maturing. It wasn’t a pay rise. I had the same pay rise as every other employee in the company.
“I will be measured in terms of the delays per flight that will have been seen [on Friday], absolutely.”
Transport Secretary Patrick McLoughlin is likely to face questions from MPs on the issue when he appears before the Transport Select Committee on Monday.
On Friday, he said the situation was “unacceptable” and asked for a full explanation from Nats about what had gone wrong and what it would do to prevent such an incident happening again.
The BBC’s political correspondent Robin Brant says Mr McLoughlin can expect to have a preliminary report from Nats on his desk by Monday.
Labour has called for ministers to “get a grip” and the chairwoman of the transport select committee, Louise Ellman, said it was “vital that we establish what happened”.
She said her committee would also call Nats and the Civil Aviation Authority to give evidence.