THE POSSIBILITY of future failures of the radar system at Dublin airport cannot be ruled out, according to a report on radar problems which caused large-scale disruption to flights this summer.
The report, from the Irish Aviation Authority (IAA), said however that such failures, which are common worldwide, should not in future lead to a shutdown of the system because of a default "recovery" mechanism.
The IAA report, which was published yesterday, blamed last July's shutdown on a "double fault", where the initial failure was compounded by a secondary fault, which prevented a recovery mechanism from operating.
The aviation authority said it was confident that measures recommended by Thales ATM, supplier of the €115 million system, "would minimise the effect of a recurrence of like or similar failure in the future".
There were chaotic scenes at Dublin airport last July when flights were grounded after icons inexplicably vanished from air traffic controllers' radar screens.
The icons were the labels that accompany each aircraft "blip" as it makes its approach, each one holding details of an aircraft's code, route, altitude and speed.
On that day the first breakdown had lasted for 10 minutes, but when it happened a second time at about 1.30pm, controllers decided, out of concern for safety, to shut down the runway to all inbound traffic.
Before the day was out, more than 200 flights had been delayed, diverted or cancelled, and thousands of passengers were left stranded across Europe. The disruption continued at a reducing rate for several days.
Ryanair, the airport's biggest user, said more than 13,000 of its passengers were affected that day, costing the airline about €1 million.
When it subsequently emerged that there had been a series of faults in the radar system since June 2nd, Ryanair called on the Department of Transport "and Ireland's useless aviation regulator" to explain why there was no contingency plan for the repeated IAA computer system failures at Dublin airport.
Aer Lingus chief executive Dermot Mannion suggested that a back-up system may be needed if the upheaval was not to repeat itself, but industry sources said a back-up system would cost as much to install as an initial system.
However, yesterday's Report of the Irish Aviation Authority into the ATM System Malfunction at Dublin Airport maintained that while "worldwide, air navigation service providers cannot rule out the possibility of failures" the IAA was "confident that the measures recommended by the system supplier Thales ATM and now being implemented will minimise the effect of a recurrence of like or similar failures of its ATM system in the future".
The report revealed that the root cause of the failures at Dublin airport was a faulty network interface card and that all of the Dublin failures had the same root cause.
It concluded that the failure was not "a single point of failure" but was caused by a double failure - a hardware failure of the network interface card and a failure of the local area network recovery mechanism.
The IAA said the system had been "stable" since July 9th and added: "IAA engineering, air traffic control, safety, support and management staff worked around the clock to resolve the issues as quickly as possible."
Recommendations
Thales ATM, suppliers of the radar system at Dublin airport, recommended:
• That additional network monitoring be undertaken. Monitoring tools and a "passive analyser" should be installed for the early identification of any similar malfunctions. This work has been completed.
• That a software programme to protect the local area network recovery mechanism be developed. This programme is currently being tested.
• That changes in procedures in relation to hardware testing be made before insertion in the operational system. These changes have been implemented.
• Thales ATM is also studying other potential improvements in the network design to prevent a recurrence.
• A spokeswoman for the IAA said it and Thales ATM had jointly supplied engineers to work on the problem. While it did not expect to have its costs refunded by Thales ATM, neither did it expect a bill from the company for its time.
