Further disruption to flights in and out of Dublin is expected tomorrow following the serious malfunction of the airport's radar system today.
Thousands of passengers experienced severe delays and cancellations to flights after the malfunction lead to the radar system being shut down and then operating at only 50 per cent capacity for most of the day.
The radar system has broken down five times over the last five weeks, the Irish Aviation Authority admitted tonight and engineers have been unable to locate the problem.
Aer Lingus cancelled 23 flights to and from Dublin and diverted ten inbound flights to Shannon, Cork and Belfast. Passengers then had to take bus transfers to Dublin.
All Aer Lingus flights into and out of Dublin after 5 pm were cancelled with the exceptions of five flights to New York, Boston, Chicago, Budapest and London.
A spokeswoman said because a number of aircraft were "displaced" after diverting, further delays were expected tomorrow. "There will definitely be a knock-on affect to our schedule", she said.
Ryanair was forced to cancel most of its 74 flights in and out of Dublin and had to divert eight inbound aircraft, seven to Shannon and one to Belfast, hitting 13,000 passengers. Aer Arann, bmi and other airlines also experienced cancellations and delays. Airlines said passengers could re-book on different flights or receive a refund.
The Irish Aviation Authority said tonight that only 12 inward flights and 12 departures were being allowed per hour, rather than the normal maximum of 25 per hour and that some restrictions could remain in place tomorrow.
There have now been five radar malfunctions of the airport's air traffic management system over the last five weeks, including two yesterday, IAA spokeswoman Lilian Cassin said.
"We had a malfunction with our air traffic management system at 11.45 am that lasted for 10 minutes," she said. She said air traffic controllers lost some functionality on their screens meaning they were unable to see the labels attached to 'blips' that signify individual aircraft. Some planes were held in UK airspace and others in airspace around Dublin airport.
"The situation was like that for 10 minutes. When the fault happened a second time at 1.30pm, we didn't have the confidence to continue so in the interests of passenger safety we took the decision to shut it down entirely" she said. The system was put back in place shortly after 3pm with limited capacity.
"We very much regret the inconvenience to passengers but this action must be taken for safety reasons. Safety is over-riding everything," she said.
Engineers from French firm Thales SA have been examining the system over the last number of days although their work had not caused today's problems. "They haven't been able to pinpoint what the problem is so far but it is specific to Dublin," Ms Cassin added.
Ryanair called for a Government investigation into the fault. The airline's head of communications Stephen McNamara said the problems with the radar in Dublin were know about for some weeks and said it was "unacceptable that there is no contingency or back up plan".
"The IAA needs to explain to passenger why flights are being delayed today by up to 5 hours, with many more cancelled. This shambles is unacceptable at Ireland's main gateway airport".
