An MP has called for bonuses to be "stripped" from a top boss after an unprecedented systems failure at the UK's national air traffic control centre.
The problem, involving computer code written a quarter of a century ago, was responsible for widespread disruption at British airports.
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 line up in Terminal Three as they wait for delayed flights at Heathrow Airport
Paul Flynn, a Labour MP, spoke out about Deakin's role.
He told The Sunday Times: "I hope after the chaos, which was dreadful, though a rare event, he will have his bonuses stripped from him."
Deakin earns more than £1 million after receiving a 45% pay rise this year, according to The Sunday Times.
Meanwhile, Nats was reportedly warned about the quality of its plans to deal with technical failures.
The Independent on Sunday said Nats gave the Civil Aviation Authority (CAA) a report earlier this year following major disruption caused by a communications problem last December.
The CAA said "themes on avoiding a recurrence" were a "good first step but lack detail and clarity", the newspaper reported.
Passengers faced travel chaos as dozens of flights at airports around the country were disrupted or cancelled on Friday and early yesterday.
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.
Deakin 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."
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."
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, 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 on Friday.
Nats declared that its systems were back to full operational capacity on Friday night, but a knock-on effect was seen at airports yesterday.
Gatwick airport said there had been 16 cancellations and seven diversions of inbound flights on Friday but said the airport was running normally yesterday.
Airports as far north as Aberdeen and Edinburgh were also affected by the computer problem. Other airports that reported delays on Friday included Manchester, Stansted and Luton.
A spokesman for the CAA said this morning it was the Nats report about the incident last December that lacked detail.
"We asked them to do a little bit more work on it," he said, adding that Nats has said this latest incident is unrelated to what caused the disruption last December.
"We said to Nats that the report that they had produced as a result of their investigation into the December failing in 2013 lacked clarity ... and subsequently there was more work done on that," he said.
He was unable to confirm whether or not that report contained information about plans Nats would put into action in the event of a failure.
Business Secretary Vince Cable suggested Nats was using "ancient" computer systems after "skimping" on investment.
He told BBC One's The Andrew Marr Show: "I think the Transport Secretary very sensibly is wanting a report on this on Monday morning to find out what has happened.
"In agencies like Nats, as in the banks and the private sector, they've been skimping on large-scale investment for very many years.
"Often the easy thing to do under financial pressure is to be penny wise and pound foolish and to forego capital investment so they've got very ancient computer systems which then crash.
"We have to maintain a high level of capital investment."