Major flight disruption which has left thousands of holidaymakers stranded overseas was caused by a problem with inbound data, air traffic control (ATC) bosses have said.
National Air Traffic Services (Nats) chief executive, Martin Rolfe, said initial investigations show the failure was due to “flight data” that was “not sufficiently standard”.
Primary and back-up systems used by the company responded by “suspending automatic processing”, he added.
Here’s what you need to know.
What caused the air traffic control issues?
Mr Rolfe said the air traffic control failure was caused by “an unusual piece of data”.
He told BBC Radio 4’s Today programme: “It wasn’t an entire system failure. It was a piece of the system, an important piece of the system.
“But in those circumstances, if we receive an unusual piece of data that we don’t recognise, it is critically important that that information – which could be erroneous – is not passed to air traffic controllers.”
Mr Rolfe was asked on the programme why the problematic flight data was not rejected by Nats “like a piece of spam”.
He replied: “Our systems are safety-critical systems, they are dealing with the lives of passengers and the travelling public.
“So even things like just throwing data away needs to be very carefully considered.
“If you throw away a critical piece of data you may end up in the next 30 seconds, a minute or an hour with something that then is not right on the screens in front of the controller.
“So it is nothing like throwing away spam.”
There is speculation the failure was caused by a French airline submitting a flight plan to Nats in the wrong format.
Downing Street did not rule out that possibility, while Nats declined to comment.
Former British Airways boss Willie Walsh said it was “staggering” that the UK’s air traffic control system was caused to “collapse” by a piece of incorrect data.
Mr Walsh, director-general of global airline body the International Air Transport Association, told Today: “I find it staggering, I really do.
“This system should be designed to reject data that’s incorrect, not to collapse the system.
“If that is true, it demonstrates a considerable weakness that must have been there for some time and I’m amazed if that is the cause of this.
“Clearly we’ll wait for the full evaluation of the problem but that explanation doesn’t stand up from what I know of the system.”
Nats is a public-private partnership which is partially owned by airlines including British Airways and easyJet and pension funds and partially owned by the government.
