Families who have unexpectedly found themselves living under a new flight path following the opening of Dublin Airport's north runway last year are calling for the Government to intervene and force the operator of Dublin Airport to change its air routes.

The parents from one such family, Dr Niamh Maher and her husband Brian Murphy, say they feel like they are living in a "war zone".

They received planning permission to build a new home near St Margaret's in 2018. At that time, there was no requirement for noise mitigation measures, such as insulation, in their new home, because the flight path expected to be in operation for the planned north runway was different to the one now in use.

The new €320m north runway at Dublin Airport opened on 24 August last year.

Since then, Dr Maher said the noise levels have been intolerable. She is calling for the Government to step in and force the operators of the airport, daa – formerly Dublin Airport Authority - to change the flight path.

"We knew the way the flight paths were meant to be, certain homes had mitigation measures in place and buyouts were offered in relation to where the planes were meant to fly," Dr Maher told Prime Time.

"We thought that everything would be absolutely fine because it wasn't anywhere in the planning that this was actually going to happen," explained Dr Niamh Maher, who works as a consultant obstetrician and gynaecologist and is a mother of two children under five.

Dr Maher said when the runway first opened her husband was in the house and immediately was concerned about the noise.

"He said it felt a bit like an earthquake, a tremor going through the house, and then it was gone. He didn't really know what it was," she said.

The flights the next morning started at 7am, Dr Maher said, adding: "I got home at midday and it literally felt like a war zone.

"My daughter, when we got home that day, she started crying because she got a huge fright from the noise of the planes. She was terrified by how low they were, and she was just like 'why is this happening?' The same with my son. He also had a huge fright and was just literally saying nothing."

Dublin Airport has wanted to have parallel runways since the 1960s, to give it greater flexibility in terms of take-off and landings, but also allow it to continue to grow.

The development of the new northern runway was proposed in 2004, and a contentious planning process proceeded over the following three years. More than 1,000 submissions were made, many from residents in surrounding areas of north county Dublin, who raised noise concerns.

During the planning process, environmental assessments were carried out in relation to places where the noise would impact residents. Those assessments were based on the planes, in westerly wind conditions, flying straight out from the proposed new runway.

Noise contour maps were drawn up based on that proposed flight path.

Based on those maps, in areas where noise levels were expected to be problematic, the Dublin Airport Authority opened a scheme to pay for special insulation to be installed in properties, and a buyout option for homeowners in specific areas who wished to move away.

Planning permission was granted by An Bord Pleanála in 2007 with conditions attached relating to times when planes could land and depart from the new runway, due to noise concerns.

No specific planning conditions were attached defining which flight paths were to be operated, but the planning process was informed by the aforementioned environmental impact assessments.

Yet when the runway opened, the flights were following a different flight path to the one used in the assessments.

Residents more than 10km away, in areas such as Ashbourne, Ratoath and Ballyboughal, started to complain about the noise.

Dublin Airport said earlier this year that some homes had been "unexpectedly overflown" and it altered the flight path in February.

However, the flight path in use since is not the direct west-east path assessed during the planning process.

It is one agreed between daa and AirNav Ireland, the body that oversees air traffic management nationally.

In an interview with Prime Time, daa CEO Kenny Jacobs said the route in use now is the "intended route" and denied that the airport authority was in breach of planning permission.

"The permission was around other aspects of the runway operation, but it wasn't on a specific flight path. Flight paths aren't governed by planning permission," he said.

Before the north runway opened but after planning had been granted, the proposed paths were subject to an AirNav final regulatory safety review.

It stipulated that it was not possible to safely operate the new north runway in parallel to the existing south runway unless planes approached and departed from 30 degrees north of the airport.

This was to ensure planes on the north runway did not interfere with planes on the missed approach route from the south runway.

A missed approach is the path followed by planes circling the airport and returning to carry out unscheduled landings, after missing their first attempted landing.

As a result the missed approach route is in use rarely, typically two or three times a day.

Some residents have questioned why AirNav Ireland did not instead stick closer to the flight path for the north runway set out during the planning process and instead alter the south runway missed approach route.

Documents seen by Prime Time reveal that AirNav Ireland did "briefly examine" the alternative of altering the missed approach route for the south runway.

This would have allowed the north runway flight path to fly close to the flight path laid out back in 2007 when planning was granted.

However, the option was ruled out at the time due to "airspace restrictions."

Correspondence from AirNav to the Department of Transport, also seen by RTÉ, said: "A primary factor that influenced our assessment of the matter is that an alternative missed approach would not be possible on the basis of a letter of agreement in place with the military."

AirNav said the airspace to the south-west of the airport was controlled by military air traffic control, and a change to the long-standing missed approach on the south runway would have an impact on other civil and military flight operations, including the Garda Air Support Unit and Weston Airport.

AirNav also said it was concerned planes would not be able to reach an altitude of 3,000ft before nearing the Casement Aerodrome at Baldonnel.

However, that rationale has been questioned by some locals with experience in aviation.

A campaign group made up of local qualified pilots have done their own flight simulations to see if it would be possible to alter the south runway missed approach in such a way as to avoid military airspace.

Prime Time took part in one of these flight simulations alongside Gareth O'Brien, a resident in Ashbourne who has been impacted by flight noise and is also a civil engineer and private pilot.

The flight simulation of a Boeing 737, a large plane that is used regularly in Dublin Airport, easily avoided both Baldonnel and Weston Airport.

In other correspondence seen by Prime Time, AirNav Ireland also say it could assist DAA in "revisiting the process for amending flight paths/missed approaches", though "any change would need to be accepted by other stakeholders, including the military".

As of now, daa has given no sign that it may look at altering the missed approach.

"The flight path now out the north runway is the one that was originally planned when the north runway opened up in August," Mr Jacobs told Prime Time.

"Between August and February of this year, there was a slight deviation in the flight path. That was a mistake that we made that we already apologised for, and we do apologise for that period of time. But the flight path today from the north runway is the flight path that was intended."

Green Party councillor Ian Carey, who represents many of the areas impacted by the flight path, said the AirNav document shows that daa has made no serious effort to comply with its planning permission.

He said decades of planning and land management was "just thrown out the window".

"It's beyond belief. Clearly, they believe they are above the law. What is positive is that it is starting to become clear that they can rectify this," Cllr Carey said.

He is calling on daa to sit down with AirNav Ireland and "immediately start the process of redesigning the airspace so that they can comply with planning, and to promptly inform Fingal County Council of their intention to do so".

"Right now, we are seeing homes, communities, and schools that were never supposed to be hit by noise, being severely impacted. While other areas, where development was not allowed and homes were insulated, are not impacted at all," Mr Carey added.

Night flights

Another stipulation of planning was that, once the north runway was in operation, the airport would have to limit night-time flights across both the south and north runway to 65, between the hours of 11pm and 7am.

A consistent breach of this cap led to an enforcement order being taken by Fingal County Council against daa, on foot of complaints from residents mainly affected when planes are landing on the south runway.

The airport authority was granted a stay on that enforcement order by the High Court pending the outcome of a judicial review application, to be heard later this year.

This is opposed by the local authority.

In a separate planning application, daa is seeking to remove the night-time flight limit and replace it with a sound quota system. That is currently with An Bord Pleanála, which has yet to rule.

The idea is that the sound quota would incentivise quieter planes to fly at night.

"You could have 65 movements on very old aircraft making far more noise than 150 movements on newer aircraft," Mr Jacobs said.

"So we want to move to a noise quota that's much, much better and that is managed between ourselves and the noise regulator."

Residents, however, worry that it will just mean there will be more planes waking them up in the middle of the night.

At the moment, Dr Maher said her kids find it hard to sleep before 11pm or stay in bed after 7am, when flights return to full operation. Under daa's planning application, they want to be able to use the runway from 6am until 12pm.

"Even if you think you're not annoyed by a loud noise, your brain processes it and you produce stress hormones." Dr Maher said.

"It causes a rise in your blood pressure. And if you're having repeated episodes of that, it can cause a chronic rise in your blood pressure, so it stays elevated."

She wants something to be done for the good of her family's health.

Kieran Dineen and Isabel Perceval's report on noise concerns related to Dublin Airport features on tonight's edition of Prime Time, at 9.35pm on RTÉ One.