Dublin Airport says a drone, which prompted the suspension of all flights earlier, hasn't been recovered and could return.
The Irish Aviation Authority ordered a 30 minute suspension of operations after a pilot spotted the device over the airfield at around 11.30 this morning.
Planes were grounded and three incoming flights were diverted as a result.
A full investigation into the incident has been launched and State agencies remain on alert for drone activity in the area.
DAA spokesperson, Siobhan O'Donnell, explains why the airfield reopened so quickly:
"In working with the various agencies, with the airlines, with the Irish Aviation Authority, who are key here (and) with the gardaí, who are another key agency here we were satisfied it was safe to reopen the airfield," she said.
Earlier: A pilot taxiing to the runway for takeoff was the person who reported the drone sighting at Dublin airport this morning.
Dublin Airport Authority’s external communications officer Siobhán O’Donnell told RTE’s News at One that the report came during a conversation between the pilot and air traffic control.
“It was an absolute sighting of a drone at the airfield.”
All activity at the airport was suspended for 30 minutes, in keeping with protocol in such circumstances, she said. “The suspension of flight operations is not taken lightly.”
Once there was no further sighting for the 30 minutes service was resumed.
During the suspension, three flights were diverted – two to Belfast and one to Shannon. Ms O’Donnell said that flight schedules are returning to normal and all airlines are confident that they will catch up this afternoon, she said.
This is the first time there has been drone activity at Dublin airport, she added.
Fianna Fáil TD James Lawless is calling on the Taoiseach and the Minister for Transport to implement his Use of Drones Bill which he introduced two years ago.
Legislation and other measures need to be taken urgently, he told News at One.
Mr Lawless said that when he last called on the Taoiseach to introduce the legislation (following the disruptive drone activity in Gatwick last December), Mr Varadkar had said there was no need.
However, Mr Lawless said that the existing legislation doesn’t go far enough especially given “the volume of devices out there.”
The capacity of drones and the technology has expanded. “Anyone can walk into a shop and buy a drone and fly it over Dublin airport without sanction,” he warned.
“At the moment the gardaí have no powers to intercept a drone. Other airports in Europe have taken measures such as having birds of prey to attack drones.
“We need to get on board, we need to get our heads around this quickly.”
By Marita Moloney & Fiachra O'Cionnaith
Flights at Dublin Airport have resumed after a confirmed drone sighting over the airfield this morning.
The airport confirmed just after midday that flight operations had been temporarily suspended for safety reasons, mirroring similar problems at Gatwick and Heathrow in London last December.
Around 15 minutes after the initial announcement was made, the DAA said that flights had resumed and it apologised to passengers for any inconvenience that may have been caused.
It said that "the safety and security of passengers is always our key priority".
Dublin Aiport said on Twitter: "Flight operations have now resumed @DublinAirport following an earlier drone sighting. We apologise for any inconvenience. The safety and security of passengers is always our key priority."
In an unwarned development just after 11.40am, Dublin airport tweeted that planes had been suspended from the airport.
It said: "For safety reasons we are temporarily suspending flight operations @DublinAirport due the confirmed sighting of a drone over the airfield. Passengers should contact their airline's website for flight updates. We will post updates here when they become available."
However, at 12.30pm, dozens of flights which were due to take off for destinations across the globe an hour earlier had yet to depart, with thousands of passengers still on board.