Ageing computer system ‘is to blame’ for air traffic control meltdown
An ageing computer system has been blamed for the air traffic control meltdown causing thousands of Brits to be left stranded across the globe.
According to one expert, the chaos may have erupted from a controller putting too many dots in a flight plan request.
The widespread disruption which started on Monday is understood to have been caused by a single rogue flight plan and continues to affect dozens of services two days later.
Controllers need basic information on each flight to populate their display, such as the flight number, aircraft type, destination and route.
If these details are not spaced and formatted in a certain way, and the computer does not recognise the data, it can cause a system collapse – a failure described this morning as ‘staggering’ by former British Airways boss Willie Walsh.
Many affected travellers are being told to wait as long as 10 days for flights home, with some forced to sleep on airport floors or take long routes by land after their flights were cancelled.
Airlines have been criticised for failing to book hotel rooms for many people who were delayed overnight.
Michele Robson, who has worked in air traffic control for more than 20 years, told the Sky News Daily podcast: ‘When there have been failures in the past, it’s normally something to do with bad information that’s been input in the incorrect format.
‘It’s a very old system, it’s been running for many years and generally, we’ve been very lucky and we don’t often have failures, or if we do, we get it back during that backup time, which is what it’s there for.
‘There have been other instances where something has been incorrectly formatted and the flight plan computer behaves in a way they’re not expecting and effectively causes it to fail, so that could be enough to potentially crash the system in effect if it was formatted incorrectly.
‘You have to space things in a certain way using a certain number of dots, as an example.
‘They do it in a very unique way that’s never been done before, otherwise, it would happen every day.
‘So it has to be something pretty unusual that they’ve input for it to happen, but it’s an old system and perhaps something was input yesterday that it’s never seen before and that’s what caused it to have this reaction where it’s failed.’
Ms Robson, who now runs the Turning Left For Less site, told MailOnline: ‘It could be something like a small operator – not a name like British Airways – doing something unusual.
‘That can be something like where an aircraft is crossing boundaries between UK and French air space several times. Also, if it is a small operator, they may not be as used to filing plans. It’s unlikely to be one dot in the wrong place.
‘I describe it as the Swiss Cheese model, lots of things added together causing the system to accept that message. For some reason, because it’s never been seen before, it accepted it, and caused the system to fail.
‘I’ve been through failures and had to go to a manual system and I think people assume it’s like in a film where there are people running around and shouting on the phone, but these people are used to working in a high-pressured job.
‘They have emergency training at least once a year, so they know exactly what to do, and take it in their stride.
Martin Rolfe, chief executive of National Air Traffic Services told BBC Radio Four’s Today programme, was asked this morning 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.’
Quizzed on the age of the system and how frequently it needs to be updated, Mr Rolfe added: ‘We have a full programme and we invest £100m a year in new systems and we are constantly evaluating which systems need to be replaced and when.
‘This is an obviously complex system with safety at the heart of it and the piece of the system we are discussing was replaced quite recently, about five years ago.’
When the failure was first flagged on Monday morning, the system went into its back-up mode – which stores up to four hours of data – rather than risk air-traffic controllers being presented with false information.
As bosses quickly realised the problem wouldn’t be fixed within that four-hour period, they decided to switch to a manual system, where all flight plans have to be entered individually.
This time-consuming process meant that controllers were unable to handle even a percentage of the usual number of aircraft moving in and out of UK airports.
The system was fully restored by 2.30pm on Monday, Mr Rolfe said, but the knock-on effect continues to be felt by passengers, who have been condemned to sleeping on airport floors while desperately waiting for their rescheduled flights.
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