The air traffic control meltdown which caused cancellation thousands of flight cancellations and delays into and out of Britain has been resolved and will not occur again, the head of NATS, the country's air traffic control provider noted Wednesday.

Thousands of Britons remain stranded abroad after 1,500 flights were canceled on Monday and disruption to schedules persisted into Tuesday. The peak holiday period means those affected are not being offered alternative flights for days.

Martin Rolfe, the CEO of NATS, said the technical problem was caused by a flight plan which was "not sufficiently standard". He said the issue had been fixed.

"We've worked incredibly hard since we restored the service back on Monday to make sure that this type of event can't happen again," he told the BBC.

Ryanair criticized NATS on Tuesday for not having a backup system. With crews and planes in the wrong places, airlines are now scrambling to get passengers home, a process with which NATS is involved.

EasyJet said it was adding five extra flights from holiday hotspots in Portugal and Spain later this week to fly people home.

NATS will present a report on what went wrong to the transport minister on Monday, Rolfe said.

Once the immediate headache of repatriation is resolved, airlines will be focused on the bill.

The cost to carriers will be substantial said Willie Walsh, the former chief executive of British Airways who now heads up global airline body IATA.

'Failure cost'

"I would imagine that at an industry level, we've been getting close to 100 million pounds ($126 million) of additional costs that airlines have encountered as a result," Walsh told BBC radio, adding that authorities needed to look at who bears that cost.

"It's very unfair because the air traffic control system which was at the heart of this failure doesn't pay a single penny."

Under current rules, passengers can claim back costs from airlines for accommodation booked as a result of a canceled flight, but they will not be entitled to compensation if the disruption is put down to "extraordinary circumstances".

NATS is a public-private partnership that is partially owned by airlines including British Airways and EasyJet and pension funds and partially owned by the government.