Repeated air traffic control failures leave us in worrying territory

To have one air traffic control failure in a fortnight may be regarded as a misfortune, to have two looks like carelessness. The UK’s air traffic services provider is coming in for a wave of criticism at the moment, so where is it all leading?

The incident at the National Air Traffic Services (Nats) main control centre in Swanwick earlier this month was extremely serious. It caused more than 2,000 flight cancellations over two days, affecting hundreds of thousands of passengers. Some were left sleeping on airport floors, others were stranded in foreign airports.

Monday’s failure at the Prestwick centre, which looks after air traffic in Scotland, northern England and northern Ireland was not as dramatic. But according to the aviation analytics company Cirium, it still led to about 150 flights being cancelled and many other delays affecting tens of thousands of travellers.

The first failure this month was attributed to a previously undetected software flaw, which had an impact due to a very specific set of circumstances combining in a millisecond. Today’s issue was blamed on a “connectivity issue” specific to the system used in Scotland. The two, Nats says, were unrelated.

But this is becoming worryingly familiar territory.

In August 2023, on a bank holiday weekend, a problem with a single aircraft’s flight plan caused a key system at Swanwick to break down, leading to cancellations and delays that affected 700,000 passengers.

Two years later, a smaller “radar-related issue” disrupted air traffic for four hours, and led to the cancellation of 150 flights.

The question is whether all of these incidents were isolated and unavoidable, or whether they point to something more systemic.