Unusual flight data causes UK air traffic control failure

A flight plan message which computers couldn’t process was the cause of the UK air traffic failure, which caused chaos for airlines over August bank holiday weekend and left thousands stranded.

According to preliminary indications, Martin Rolfe said that the computer system of National Air Traffic Services collapsed on Wednesday because it “did not recognise a message”.

“The piece failed and it failed because the message was not recognised. . . Rolfe said on BBC Radio 4 that the delays meant they couldn’t process as many flights at once as usual.

After air traffic controllers severely limited the number of aircraft arriving and departing UK airports, more than one-quarter (25%) of all inbound and outbound UK flight were cancelled and many others delayed on Monday.

The outage, which Nats is currently investigating before delivering a government report next week, affected the system’s ability to automatically process messages from airlines detailing their flight plans and timings. Employees were forced to manually enter the information.

Both Nats’ primary automatic processing system and secondary automated processing systems were suspended due to the incorrect message.

Rolfe stated that the system was not broken and airspace was slowed, rather than shut down. Nats, a public-private joint venture owned by British Airways, easyJet and pension funds, as well as the UK government, typically handles around 2mn flights per year.

By 2.30 pm on Monday, operations had returned to normal capacity. However, thousands of passengers are still stuck in the queue as airlines try to clear their backlog.

On Wednesday, Prime Minister Rishi sunak said that it was vital for carriers to work together in order to bring back stranded Britons.

He said that it was important for airlines to honor their obligations towards passengers in terms of accommodation and flights so they can get them home.

In the meantime, airline executives called on Nats for them to pay their expenses. Willie Walsh of the International Air Transport Association (which represents airlines) said Nats should pay a fine for the incident. He noted that the bill to the airlines could be up to PS100mn.

Walsh told BBC that this incident provided an opportunity for the industry to examine the way compensation is handled for passengers, and ensure that those who are responsible for cancellations or delays “ultimately” bear the costs.

The former British Airways Chief Executive added that “we need to be careful if [Nats] were charged, if fined. . . “The regulatory model is that they do not pass on the cost to the airlines.”

Rolfe stated that the failure is “extremely rare” and it has affected a single part of the system.

He said that if we received an unusual data piece that we didn’t recognize, it was important to not pass on the information that could be incorrect.

Rory Boland is the travel editor for consumer group Which?. He said that stranded travelers should know that their airline has a duty to reroute, even if it means purchasing a ticket on a competitor carrier – a rule some airlines seem to be disregarding.

He added that passengers should be provided with food, refreshments, and overnight accommodations if necessary.

The Civil Aviation Authority (the aviation regulator) said that affected passengers were unlikely to receive compensation as “this incident would likely be considered exceptional circumstances”.