The UK's Civil Aviation Authority (CAA) is due to hold an inquiry into the failure in air traffic management systems at NATS (National Air Traffic Services) that occured on Friday 12 December.
The disruption, which lasted from about 3.30pm to 7pm on Friday, saw over 150 flights from London airports cancelled and hundreds more delayed. NATS has has experienced a number of technical failures since the Swanwick, Hampshire-based centre opened in 2002, and almost exactly a year ago almost 300 flights were cancelled and 1,400 delayed over two days, also as a result of a server failure.
Last week's problem was caused by a glitch in one of the 50 systems at NATS' centre in Swanwick. The server running the flight data processing system went down, apparently as a result of a software flaw.
Despite assurances from NATS that it has been fixed, software experts have warned its systems could collapse again.
A spokesman for CAST software said "the issue is one of structure, not of quantity" and "an upcoming change of core software is likely to exacerbate the issue".
He added: "The new systems will also likely introduce yet more complexity to a system which is already proving unreliable. In fact, as the delivery date gets nearer, significant structural quality problems that have gone undetected become harder to fix on schedule and system risk goes up significantly."
Most of NATS' IT systems are decades old, and so cannot always link up effectively with modern software and hardware.
Chief executive Richard Deakin admitted: "We're better off moving to an entirely new, internet-based system rather than work out how old [computer] languages can communicate with new systems."
The CAA, which regulates air travel, has said it will investigate the root causes of the incident, NATS handling of it, levels of resilience and what steps can be taken to avoid technology or process failures in future.
The inquiry will be run an independent chair supported by a panel of NATS experts, a CAA board member and independent experts on IT, operations and air traffic management.
Yesterday business secretary Vince Cable accused NATS of running "ancient computer systems, which then crash" as a result of "skimping on large-scale investment". He said the organisation had suffered as a result of "being penny wise and pound foolish".
However, Deakin insisted the error was not as a result of investment. He said it was "one error, or limitation, in four million lines of code", and claimed the organisation is due to spend £575 million on new systems over the next five years.
The CAA warned NATS four months ago that there could be a repeat of the disruption of December 2013, according to the Independent on Sunday.
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