The Irish Aviation Authority has confirmed that a new €115 million air traffic control system in use at Dublin Airport failed last Sunday morning while handling "live" aircraft.
The new system was operating on a "complete control" basis for the first time, having assumed responsibility for all aircraft movements at the airport from about 4 p.m. on Saturday.
Just after 11 a.m. on Sunday, it failed to identify aircraft on air traffic controllers' radar screens. It was one of the busiest mornings at the airport so far this year, with 70,000 people travelling.
As soon as the fault was detected the new system was replaced by the old, which was on standby as a precautionary safety measure.
A spokeswoman for the Irish Aviation Authority, Ms Lilian Cassin, said the changeover was "seamless", and said "safety was not compromised". The new system is already in operation full-time at Shannon, where there have been no difficulties, Ms Cassin said.
It was being phased in at Dublin Airport, having gone live for the first time on April 22nd last. The system was bought from the French company Thales, and the €115 million investment included a provision of about €25 million for the facilities at Shannon, according to the authority.
Air traffic controllers who monitor the approach and take-off of aircraft at Dublin Airport, or aircraft affecting the airport, have "essentially three lines of information on their screens, although other information is available to them", said Ms Cassin.
"The first is the call sign identity, such as Aer Lingus EIN 123. The next line is the altitude, and the third is the speed. The display of information to the controllers should have identified the aircraft by their call signs but this did not happen."
Instead the call signs were replaced by "a numbered code" which could ultimately have also identified the aircraft. However, because of the need for swift action and the potentially serious nature of the failure, control of the aircraft was immediately passed to the old system, where a shadow crew was "in hot standby mode", she said.
Ms Cassin stressed the incident showed that the air traffic controllers' safety systems worked. "Because of the nature of the work the safety aspect is always paramount. We have to plan for things to go wrong and this shows our safety systems worked."
A spokeswoman for Aer Rianta said about one million passengers per month would be coming through Dublin Airport between now and the end of the summer. Sundays were, she said, among the busiest days at the airport because of the large numbers of charter flights.
