The public is being urged not to be “alarmed” if they spot unusual activity in Irish skies after dark over the coming days.
Those living near Dublin Airport or anyone who tracks aircraft online may spot some strange flight patterns this week.
Dublin Airport says the public should not be “alarmed” as it is just the airport carrying out mandatory testing.
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Subject to weather conditions, it’s due to happen on Monday, Tuesday and Wednesday between 11pm and 4am.
A spokesperson shared a picture of what the public can expect on Twitter.
They said: “If you see flight patterns like those pictured over the coming days, don't be alarmed. It's just us carrying out mandatory testing of our Instrument Landing Systems (which offer guidance to landing aircraft).
“We run these tests twice per year for safety reasons. Subject to weather conditions, testing will take place between 11pm - 4am on Monday (April 25), Tuesday and Wednesday of this week.”
It comes as new advice has been issued to anyone due to fly out of Dublin Airport in the coming weeks.
Passengers flying to the UK or Europe should arrive up to two and a half hours before their flight, while anyone going on long-haul flights should get there up to three and a half hours before their flight.
The daa said this will alleviate pressure on the passenger security screening area and enable an enhanced airside travel experience.
It also recommends that passengers check with their airline in advance of travelling to the airport regarding when check-in and bag drop-off opens and to plan their arrival at the airport based on that information.
Passengers are also encouraged, where possible, to check in for their flight online.
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