In pretty much every discussion and article about this runway someone will say something along the line of “it’s all very technical”. One of the “very technical” things that is crucial to this whole discussion is the departure routes, what most people call the flight paths, being flown by the aircraft, especially on take off which is the noisiest part of any flight.
To use an analogy, departure routes are effectively motorways in the sky. When you plan, design and get permission for a runway a portion of the exercise is the actual concrete structure on the airfield. The rest of it is about where the aircraft will go when they leave the ground on departure (take-off) and approach the ground on arrival. In this way it’s not like when you build a building, it’s more like a motorway.
In the case of the north runway at Dublin Airport daa and AirNav changed the departure routes, leading to what daa describes as residents being “unexpectedly overflown”. What has happened to residents is that a “motorway” has “unexpectedly” been built through their front gardens.
The planning application put the departure routes somewhere entirely different. Not a little bit off: up to around 13 kilometres from where they are flown today. Imagine you consulted, assessed, designed and got planning permission to build the M1. Nine years later you consulted on the M2, but only in Fingal. And then you built the M3, having never told anyone there was going to be an M3. Would you call that a breach of a planning condition, or a whole other motorway without planning permission? The principle is exactly the same for the departure routes.
There is an important difference between a motorway in the wrong place and a departure route in the wrong place that makes this much easier to fix. The concrete doesn’t need to move, only lines on a chart.
This is what the charts look like for pilots and ATC. To simplify and declutter them, they ignore almost everything on the ground. In the next section we try to show the history of the tracks daa has worked up over the years and the effect the changes have on the people who live under the Motorway in the Sky they define.
So what does that look like on the ground?
This is the area to the north of the new runway 28R (Runway numbering explained here). Aircraft departing were supposed to follow this blue line (cyan for the graphic nerds): the route assessed in the planning application. Our randomly chosen example house (not my house!) is 3.5km from the closest point on that track. This was their expectation when the planning was granted. They will hear the aircraft take off, but it is not destructive to their ability to live in their home. Note: this shows only runway 28 departures as this is well over 70% of departures from Dublin Airport due to the prevailing wind.
In 2016 daa published a noise consultation for their proposed modification of the departure track. This included an immediate 15 degree turn for departing aircraft to allow simultaneous departures from 28R and 28L. That is the ICAO rule for two departures side by side: their tracks must split by at least 15 degrees straight after take-off (ICAO Doc 9643, Chapter 3). All aircraft except transatlantic flights were proposed to use this turn. Now our example house is 1.7 km from the route; a lot noisier and the turn reduces climb efficiency of the aircraft so they will now be closer to the ground too. Keep in mind that while daa carried out this “public consultation”, the planning permission has not been changed to reflect the routes they intend to use.
daa says the IAA set it a safety requirement for operating parallel runways. This is a different rule in the same ICAO manual, for a departure against a landing that has to go around: the missed approach for 28L (landing traffic on the old runway) and the departure track for 28R must diverge by 30 degrees (Doc 9643, Chapter 4). The rule does not say which of the two has to turn. Instead of changing the missed approach for 28L (about one flight a day “goes missed”), they turned every one of the 300+ flights departing 28R shown here on the magenta line. Our example house is now directly under the route and again with lower climb efficiency in a 30 degree turn, the aircraft is much lower to the ground. You may also note the extra track with an additional turn of about 56 degrees to the north meaning within 5km of leaving the runway all eastbound aircraft (the majority) are turned about 86 degrees from the runway heading where no one ever expected them to be. The full story of that rule is in How a safety rule became a turn aimed at Ratoath.
This is what it looks like for only a handful of departures. Think about 300+ per day! This makes it look like Ashbourne misses it but most of the tracks (heading into mainland Europe and the UK) pass within 3 km of the centre of Ashbourne, where around 16,000 people live, at 3,500 to 4,500ft while operating at climb power (maximum noise). Ratoath, where over 10,000 people live, has a waypoint (DW991) on its eastern edge, just before the aircraft fly right over Ratoath. It’s mostly used by flights heading south; these ones were going to Lanzarote. Yes, we’re turning them north, climbing over Ratoath, to fly south!
Across the whole route, our study counts about 14,000 people newly overflown, within 1.5 km each side of the routes flown, against about 1,000 on routes consistent with the assessed design. Within 3 km each side, about 30,000 people are newly affected, against about 1,200. The studies, with their data and methods.
Our Proposal
So what’s the answer. Our proposed departure track is shown here in yellow. The immediate 15 degree turn that the 2016 noise study proposed is not necessary. The same ICAO rule for two departures side by side allows a smaller split: 10 degrees, where both aircraft fly a satellite-navigation (RNAV) departure and the turn starts within 2 nautical miles of the end of the runway (Doc 9643, Chapter 3). So the yellow track flies straight ahead for under 2 nautical miles and then turns 10 degrees. This increases the efficiency of the climb by keeping the wings level longer and then minimizes the turn required. The 30 degrees between a departure and the 28L missed approach (Chapter 4) is met by turning the missed approach instead, the pink line below, not every departure. This permits take off from both runways at the same time, which should increase any airport’s departure capacity by at least 50%. This works because all landings occurring on 28L (the old runway) can have take offs in between. This is exactly how it operated before the new runway was built, so daa and ATC know how to do this already. This will also allow destinations to the south to take off from the south runway and those heading transatlantic, or east to Northern Europe to use the north runway. Read the Win-Win Proposal.
So now the airplanes will fly over high density neighborhoods along that pink line, right? Yes, but … Each day
- 300+ airplanes will fly along the yellow line while climbing out from a standing start on the runway and climbing all the way making maximum noise.
- About 1 airplane will fly along the pink line and remember these are aircraft that failed to land on 28L and are executing a “missed approach” so they are already flying at least 130 knots at the start of the runway while already 200+ ft in the air so they get to altitude much quicker. They are also only climbing to 4000ft at which point they level off which makes them much quieter. The magenta area is industrial so the first residential areas is reached after 5km.
- The proposal has already been flight tested in the training simulator for the aircraft that use Dublin Airport.
Who are we and why do we think we know how to come up with a proposal?
First published 11 August 2023. Updated October 2026: the population figures now come from our published studies, each angle is tied to the ICAO rule it comes from, and the page links to the stories that tell the history in detail.