December 12, 2014

expert reaction to London flight disruption

A technical problem at the UK’s air traffic control centre has caused disruption to flights in and out of the country.

Prof. Martyn Thomas FREng, Visiting Professor of Software Engineering, University of Oxford, said:

“I don’t know the details of this specific computer failure but I did review the technical changes made in response to a few computer failures in the early 2000s. I understand the system has now been restored and NATS are clearing the backlog slowly.

“Some of NATS’ computer systems are very old – the National Airspace System (NAS) that performs flight data processing is software that dates from the 1960s. Interfacing new systems to this old software can create difficulties.

“NATS has an outstanding safety record.  They won’t have compromised safety, which always takes priority over delays; but delays were inevitable once the controllers lost the support of their computer-based tools, because without the tools the controllers cannot handle as many simultaneous aircraft.”

Prof. Ian Allison, Head of the School of Computing Science and Digital Media at Robert Gordon University (RGU), said:

“This failure is most surprising as these systems have high levels of resilience built into them. Software is written to a high level of engineering to ensure the safety of passengers. On this occasion it seems to be a server failure – i.e. an infrastructure failure on which the software is running. I am sure the systems will have been designed to cope with this type of failure – normally to “fail over” safely to another mirror server. So it seems to be a major incident that has caused the contingency plans to fail as well as the primary system. It is difficult to assess the cause or how long it will be before the system is returned to normal without knowing more but I am sure that they will be looking to restore the system using a back-up data centre.”

Declared interests

None declared