The August bank holiday air traffic control chaos happened as Nats “collapsed their system”, Ryanair boss Michael O’Leary told MPs.

Around 2,000 flights at airports across the UK were cancelled when Nats’s system for automatically processing flight plans failed on August 28.

The company has previously said the problem was caused by a flight plan featuring two waypoints – which use letters and numbers to represent locations – with identical names.

Giving evidence to the Commons’ Transport Select Committee, Mr O’Leary said: “What fundamentally this committee needs to get the bottom of today is why did they collapse their system?”

He added: “We have written confirmation from other ATC (providers).

“(They) said they routinely and regularly receive flight plans that have duplicate waypoints in them. So this is not something complicated.

“All of their systems are designed (so that) when they receive a duplicate flight plan like that (they) reject it and they deal with it manually.

“This is routine. It happens on a daily basis both within Nats and in every other European ATC system.

“Yet on Monday August 28, bank holiday Monday here, Nats collapsed their system at 8.30am.”

He continued: “You lot (Nats) not just collapsed the main system, you collapsed your backup system, and all your engineers were sitting at home watching morning television instead of being where they’re supposed to be.”

Mr O’Leary said the cost to Ryanair of paying for meals, drinks and hotel rooms for affected passengers was £15 million.

He told the committee: “We wrote to Martin Rolfe, the vastly overpaid and incompetent chief executive of UK Nats, asking for reimbursement of our £15 million in right to care expenses, and we get a reply saying ‘it’s not in our remit’.

“You don’t need a remit to do the right thing.

“Instead of paying £50 million in dividends to your shareholders on an annual basis, you should be reimbursing the airlines for the right to care expenses that you inflicted upon us.”

EasyJet chief commercial officer Sophie Dekkers told the hearing that the cost to the carrier was “not dissimilar to Ryanair’s”.

Tim Alderslade, chief executive of industry body Airlines UK, said his organisation “hasn’t even had a response” to a letter it wrote to Nats asking for those losses to be recouped.

He went on: “We are always the insurer of last resort.

“They could if they wanted to repay that money, or they could pay 25% or 50% of it back.

“It’s tens of millions of pounds and we think they have it.

“To not to respond to that, I think is really disappointing.”

Mr Rolfe told the committee the flight plan which led to the system failure was “incredibly unusual” and “unlike any we’d seen before”.

He said: “It was sufficiently unusual with not just duplicate waypoints, as you may have been informed earlier, but the combination of them, the sequence of them, and it was sufficiently different that the system decided the safest course of action was to stop processing and essentially allow a human to intervene.

“That’s the basis of our safety critical systems.

“In the event that something happens that is unexplainable, it is passed on to humans because ultimately humans are better at interpreting confusing data than computers are.

“That’s what happened. As a result of that, we reduced the flow of traffic in the skies over the UK, and that is simply to make sure that the air traffic controllers can safely handle what’s coming when they don’t have all the information that you might otherwise expect them to have.

“Now regrettably, obviously, that results in cancellations, delays.”

He went on: “In terms of other providers around Europe, they suffer from similar incidents, not necessarily exactly the same software, but it’s very common.”

On the issue of some engineers working from home, Mr Rolfe insisted Nats was “a very serious organisation” with “the right number of engineers on site”.

He added: “In addition, we do have the ability, as you would expect I think any modern company to have, to be able to have people dial in remotely to help assist when things fail.

“That’s exactly what we did.”

On the issue of reimbursing airlines for their costs, Mr Rolfe said: “I absolutely understand the frustration of the airlines in the context of the expenses they have to incur.”

He added the issue “goes back to effectively the way Nats is constructed”, which means it must “prioritise safety over all other things”.

He said airlines will receive “rebates in future charges” if performance falls below certain standards, but Tory MP Iain Stewart, who chairs the committee, described that as “a very opaque system”.