Flights at Dublin Airport were delayed by up to four hours yesterday because of problems caused by Irish Aviation Authority's introduction of a new air traffic control system.
Ryanair has warned passengers travelling with it to or from Dublin in coming days that the delays will continue over the weekend and through the week.
The new air traffic control computer and radar system has been introduced on a phased basis at Dublin Airport since April.
Part of the roll-out involves a reduction in the number of flights that air traffic controllers can process simultaneously. From lunchtime yesterday air traffic control was operating at a 70 per cent capacity.
This resulted in delays for around 80 per cent of flights arriving and departing.
A spokeswoman for Aer Rianta said while most delays were "between five minutes and an hour", some flights were held up for as long as four hours.
She added the Irish Aviation Authority had warned airlines last month that the introduction of the system would result in "teething problems and delays".
A spokesman for the Irish Aviation Authority said the new system was operating at 70 per cent campacity as a precaution.
The new system went live for the first time on April 22nd last. Last Sunday morning it failed while handling "live" traffic. 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.
The new 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.
Ryanair said it would continue discussions with Dublin air traffic control "to try to assist them to eliminate these delays and restore capacity to normal levels". It added passengers should check in for flights as normal two hours in advance of scheduled departure time.
Some one million passengers, many on charter flights, are expected to use the airport this week and every week until the end of the summer.
