daa checks whether departing planes stay inside a corridor drawn on the map. Call it a box. On 24 August 2022, the day the North Runway opened, the culmination of a fifteen-year project, the new runway didn’t have one. Not a proper one. daa’s noise officer wrote to the Aviation Authority that afternoon. For now, he’d borrow the shape used on the old runway. “I know this doesn’t suit the SIDS as published with the 75 and 15 deg turn”.
The published turn wasn’t 15 degrees. It was 30. On opening day, the man building the box to check noise compliance had the turn wrong.
Three weeks later he set out the plan. There’d be no checking of North Runway departures until October. “In short we will complete the Aug and Sep Noise reports ignoring NR operation. To not do this will leave a backlog of thousands of complaints to manage.”
And the old shape had a problem. It started past the end of the runway, only 180 metres wide. Planes could be “outside of the corridor before they have a chance to be in it”.
His fix was to copy the London airports. Heathrow, Gatwick and Stansted, he wrote, have corridors that start 2,000 metres down the runway, with a first gate 240 metres wide. That way “all aircraft depart the runway within the NPR and then have a fighting chance to remain within it.”
NPR stands for Noise Preferential Route. The idea, as daa’s own consultants described it in 2017, was to draw a line on the map showing “the preferred route for aircraft to fly in order to minimise their noise impact on the ground”. What came over from London for the new runway was the measurements for the box that tests compliance with that line. The name got transferred from the line to the box.
Remember “a fighting chance”.
daa decided the corridors would then widen out to a “standard width” of 1,800 metres. Which they are, except in the places where they’re 2,400 metres wide. Because, that’s why!
Did they tell anyone? Not exactly. In February 2023 Fingal, acting as the noise regulator, wrote to daa. It had come across these new corridors in one of daa’s letters. “It is not evident that there is significance, from a noise impact perspective, to these routes.” Please explain.
daa wrote back in March 2023. Ninety metres either side, two-thirds of the way down the runway, widening to “a maximum width of 1800m”. The corridors, it said, “are described within the Aeronautical Information Publication”.
They are. The official publication says the corridors start 180 metres wide at the end of the runway, not two-thirds of the way down it. And the chart has stretches 2,400 metres wide.
Three versions of the box. One name.
And what’s the box for? daa’s letter told the regulator: “The aim of the noise corridor is that where safe to do, the aircraft are kept on the SID which aims to route the aircraft away from heavily populated areas.”
Why Vienna? Because, as daa put it, “we have a similar sharp turn off the runway”. Similar turns, different reason. In Vienna’s own rules, its departure routes “are also noise abatement procedures; strict adherence is compulsory within the limits of performance of the aircraft”. The turns are there for the people below. Its corridors are “agreed”, up to 6,000 feet, because “The interest of the affected population is that aircraft comply with agreed corridors”. Dublin’s turn goes over 14,000 people who were never asked about it.
The official aviation publication calls the box an “environmental corridor”. Its shape comes from the “take-off flight path area”, which is a safety rule about obstacles.
So: a measuring box, shaped by obstacle rules, sized to give planes a fighting chance, under a name Dublin already used, borrowed from London.
How long should the box be? In early 2023 daa’s noise officer was “angling toward the worst performing aircraft” to set it. And daa’s software consultant had a word of advice: “You want aircraft that are off-track. Anything less than that and you’ll be accused of just drawing corridors around the traffic and saying everything is compliant.”
So leave a few planes outside, or, in the consultant’s words, you’ll “be accused of just drawing corridors around the traffic”.
The so-called NPR turns right off the end of the runway, over the homes of about 14,000 people who never had planes over them before. In March 2024 a resident asked the noise regulator the obvious question: who defined it, and “what criteria made it preferential to place the noise along this route”?
The noise regulator answered. It “was not involved in the design, naming or implementation of these corridors and has no information evidencing the significance, from a noise perspective, of the use of this term.”
daa kept the name.
Every year the law requires daa to prepare what’s called a Compliance Report. In it, there’s a table of how well the planes stick to the so-called NPR. The North Runway’s figure for 2024: 92.8 per cent. And next to it, a column headed “Opinion On Compliance”. The entries in that column read things like “Continual improvement” and “Compliance on-going”.
Ninety-two point eight per cent of what, though? Not of the route the planes are meant to fly. We asked daa how many flights straying off the published route it had passed to air traffic control. “daa do not refer instances of flights deviating from the published SID to AirNav.” What it tracks is deviations from its own box.
Compliance with the box. Not with the route. Totally different thing.
And the routes the runway was assessed on, the ones the planning permission rested on, went straight out. Every North Runway departure turns. So against the routes that were actually assessed, the score isn’t 92.8 per cent. It’s zero percent.
How far off?
On the route most westerly departures fly, at about twelve kilometres from the end of the runway, the plane is 13.3 kilometres from where the assessed route would have put it.
The rules expect it within 1.85 kilometres, 95 per cent of the time.
Coming in to land, the beam it follows is 210 metres wide at the runway.
Thirteen point three kilometres.
And when planes do leave the box, whose fault is it? daa’s monthly report says planes leaving the box and coming back in is “a known issue for a small percentage of aircraft and Dublin Airport is working with the airlines and the aircraft manufacturer on resolving it.” Its Compliance Report says the published routes “are contained within the NPRs”, but on aircraft “equipped with different avionics, slight variance” may occur.
The airlines. The manufacturer. The avionics. Never the box. A clear case of BSE: Blame Somebody Else.
“Different avionics” means this. There are two kinds of flight computer in the fleet. One works hard to hold the line drawn on the chart, through the tight turn and all. The other turns when it’s ready and points itself at the next waypoint. Both, says the airline, are flying the published route. daa drew a box around one and implies the other is faulty!
We tracked the departures ourselves. On one day in March 2026, one aircraft type left the box on 14 of its 16 departures off the North Runway. It turns earlier and tighter than the rest, and the box has no room on that side. An airline that flies it had already written to daa, in April 2025: “this misrepresentation of our compliance with the North Runway Standard Instrument Departures (SIDs) on 28R is unacceptable.”
So, here’s where we’ve landed. On opening day, the man building the box had the turn wrong, and the new runway went six weeks unchecked, the box not built yet. Then he borrowed London’s measurements so planes would have a fighting chance of staying inside. The box got a name that means “the route chosen to spare people from noise”. The noise regulator said, in writing, that it had nothing to do with it and had no information on any noise significance in the name. The name stuck. When a plane its airline says is flying the published route ends up outside the box, daa blames the plane. And every year the box gets a score, to one decimal place, in a Compliance Report, under the heading “Opinion On Compliance”.
Compliance with the box: 92.8 per cent. With the routes that were assessed: zero.
Nobody chose today’s route to spare anybody. But it has a name that says somebody did, and a score that says it’s working.
Sources
- daa, email from its noise officer replying on an email thread with the Irish Aviation Authority, 24 August 2022, 16:05 (the borrowed corridor shape; “I know this doesn’t suit the SIDS as published with the 75 and 15 deg turn”). Released to NRTG under AIE request 2615 (daa), on internal review, 7 August 2026 (record 8)
- AIP Ireland (published by the Irish Aviation Authority, now by AirNav Ireland), Dublin Airport Runway 28R standard instrument departure charts as published for the North Runway’s opening in August 2022 (the turn of 30 degrees from the end of the runway). Current edition: https://www.airnav.ie/air-traffic-management/aeronautical-information-management/aip-package; NRTG holds a copy of the 2022 edition
- daa, internal email from its noise officer to colleagues, “NR Noise corridors”, 14 September 2022 (“In short we will complete the Aug and Sep Noise reports ignoring NR operation. To not do this will leave a backlog of thousands of complaints to manage.”; the existing corridor 180 m wide and beginning beyond the runway, so aircraft are “outside of the corridor before they have a chance to be in it”; the proposal to copy Heathrow, Gatwick and Stansted, starting 2,000 m down the runway with a first gate 240 m wide, so that “all aircraft depart the runway within the NPR and then have a fighting chance to remain within it”; widening to a “standard width of 1800m”). Released to NRTG under AIE request 2615 (daa), on internal review, 7 August 2026 (record 7)
- Bickerdike Allen Partners for daa, Dublin Airport North Runway: Investigation into Noise Impact of Potential Departure Routes, report A9843-R04-DC Final, 12 July 2017 (the custom of drawing a line on the map to identify “the preferred route for aircraft to fly in order to minimise their noise impact on the ground”). Released to NRTG under AIE request AIE/2026/014 (Fingal County Council), 15 May 2026, and under AIE request 2615 (daa), on internal review, 7 August 2026
- daa, North Runway Noise Preferential Route corridor chart, as published by daa; a copy of the chart is in the data deposit of NRTG’s GIS study (https://doi.org/10.5281/zenodo.19567671). The width of about 2,400 metres on the westerly branches was measured by NRTG on that chart
- Aircraft Noise Competent Authority (Fingal County Council), letter to daa on the “Indicative Noise Corridors”, 28 February 2023 (“It is not evident that there is significance, from a noise impact perspective, to these routes.”). Released to NRTG under AIE request AIE/2026/014 (Fingal County Council), 15 May 2026, and under AIE request 2615 (daa), on internal review, 7 August 2026
- daa, letter to the Aircraft Noise Competent Authority, “ANCA Noise Corridor Info Request”, 15 March 2023 (90 m either side two-thirds of the way down the runway, widening to “a maximum width of 1800m”; the corridors “are described within the Aeronautical Information Publication”; “The aim of the noise corridor is that where safe to do, the aircraft are kept on the SID which aims to route the aircraft away from heavily populated areas.”). Released to NRTG under AIE request AIE/2026/014 (Fingal County Council), 15 May 2026, and under AIE request 2615 (daa), on internal review, 7 August 2026
- AIP Ireland (AirNav Ireland), Dublin Airport, EIDW AD 2.21, Noise Abatement Procedures, paragraph 8 (“environmental corridors which are based on runway take-off flight path areas”, 180 m wide at the departure end of the clearway, widening to a maximum of 1,800 m), as in force in August 2026. https://www.airnav.ie/air-traffic-management/aeronautical-information-management/aip-package
- daa, email thread with Vienna Airport on noise corridors, forwarded internally on 14 March 2023: daa’s enquiry of 24 October 2022 (“we have a similar sharp turn off the runway”); Vienna’s reply of 31 January 2023 (corridors checked up to 6,000 feet; “The interest of the affected population is that aircraft comply with agreed corridors”); daa’s noise officer “angling toward the worst performing aircraft” for the corridor length; and the advice of daa’s noise-monitoring software supplier (“You want aircraft that are off-track. Anything less than that and you’ll be accused of just drawing corridors around the traffic and saying everything is compliant.”). Released to NRTG under AIE request 2615 (daa), on internal review, 7 August 2026 (record 3)
- AIP Austria (Austro Control), Vienna-Schwechat, LOWW AD 2.21, Noise Abatement Procedures, paragraph 2.4, AIRAC AMDT 308, as in force in August 2026 (“The published standard instrument departure routes (SID) are also noise abatement procedures; strict adherence is compulsory within the limits of performance of the aircraft”). https://eaip.austrocontrol.at
- NRTG, Quantifying Noise Impact of Dublin Airport’s North Runway Departure Routes: An EIA-Conformance Gap Analysis, version 1.0, 15 April 2026 (13,923 residents newly overflown by the North Runway departure routes, within 1.5 km each side of the track). Zenodo: https://doi.org/10.5281/zenodo.19567671
- Question put to the Aircraft Noise Competent Authority by email, 12 March 2024 (who defined the Noise Preferential Route and “what criteria made it preferential to place the noise along this route”), and the Authority’s reply, Ref. 2024/0119, 13 March 2024 (it “was not involved in the design, naming or implementation of these corridors and has no information evidencing the significance, from a noise perspective, of the use of this term.”). NRTG holds copies
- daa, Annual Compliance Report 2024, prepared under section 19 of the Aircraft Noise (Dublin Airport) Regulation Act 2019, Revision 2, 30 October 2025 (North Runway Noise Preferential Route adherence 92.8 per cent for 2024; the column “Opinion On Compliance”, with entries such as “Continual improvement” and “Compliance on-going”; the published routes “are contained within the NPRs, but when flown by aircraft equipped with different avionics, slight variance” may occur). Published by the Aircraft Noise Competent Authority: https://www.fingal.ie/aircraftnoiseca/airport-compliance-reports
- daa, decision on AIE request 2622, 2 July 2026 (“daa do not refer instances of flights deviating from the published SID to AirNav. daa do track instances of fight [sic] deviations from the NPR.”). NRTG holds a copy
- An Bord Pleanála, decision granting permission for the North Runway, ref. PL06F.217429 (Fingal County Council reg. ref. F04A/1755), August 2007, and the Environmental Impact Statement on which it was granted (2004, with its 2005 addendum), which assessed departures flying straight out. On the planning file for F04A/1755 at Fingal County Council; NRTG holds copies
- NRTG, application to Fingal County Council for a declaration under section 5 of the Planning and Development Act 2000, lodged 14 September 2026, with its annex (on the route flown by most westerly departures, at 12,335 m along track, the aircraft is 13.34 km from the straight-ahead route that was assessed). NRTG holds a copy
- International Civil Aviation Organization (ICAO), Performance-based Navigation (PBN) Manual, Doc 9613, RNAV 1 specification (lateral total system error within 1 nautical mile, 1,852 m, for at least 95 per cent of the flight time). Available from ICAO by title
- International Civil Aviation Organization (ICAO), Procedures for Air Navigation Services: Aircraft Operations, Volume II, Construction of Visual and Instrument Flight Procedures, Doc 8168, Seventh Edition, 2020 (ILS course sector width of 210 m at the runway threshold). Available from ICAO by title
- daa, Dublin Airport Monthly Noise and Operations Report, December 2024 (flights leaving and re-entering the North Runway Noise Preferential Route are “a known issue for a small percentage of aircraft and Dublin Airport is working with the airlines and the aircraft manufacturer on resolving it.”). Published by daa: https://www.dublinairport.com/corporate/environmental-social-governance/noise/aircraft-noise/airport-noise-plans-and-reports
- Letters from a Dublin-based airline’s Chief Operations Officer to daa’s Managing Director, 22 January 2025 and 29 April 2025 (its departures compliant with the published 28R routes, as confirmed by air traffic control; “this misrepresentation of our compliance with the North Runway Standard Instrument Departures (SIDs) on 28R is unacceptable”). Made public by a member of the Dáil in March 2026; NRTG holds copies
- NRTG, analysis of ADS-B flight tracks of North Runway departures on 25 March 2026 against daa’s published corridor (one aircraft type leaving the corridor on 14 of its 16 departures). NRTG holds the data and method