Frequently Asked Questions

Glasgow Airport is proposing to make changes to the arrival and departure routes to introduce Performance Based Navigation (PBN) technology. We are also proposing to make changes to the Controlled Airspace (CAS) within the vicinity of Glasgow Airport. You can see the changes we proposed during our public consultation on this website here.

Glasgow Airport is required to modernise its airspace by the UK Government’s Airspace Modernisation Strategy, which is driving a nationwide upgrade to UK airspace. Across the country, eighteen airports including Glasgow Airport are developing Airspace Change Proposals to meet the objectives outlined by the Strategy.

Performance Based Navigation (PBN) forms of a key part of the UK Government’s Airspace Modernisation Strategy (AMS). PBN improves the accuracy of where aircraft fly by using modern satellite navigation, rather than outdated ground-based navigation aids (conventional navigation).

Vectoring is when Air Traffic Control (ATC) provide an instruction to pilots in the form of a direction (heading based on a compass bearing). ATC may also instruct pilots to climb or descend. ATC do this to ensure aircraft are safely separated and where possible are given the most efficient routes.

We have concluded public consultation as part of Stage 3. This stage included carrying out our second appraisal on the remaining options, called the Full Options Appraisal (FOA), and planning and preparing for this consultation by producing a Consultation Strategy and our consultation material. The material shared during public consultation is available to view here.

You can view the consultation responses we have received on our online portal. All feedback will be read, and we will collate, review and categorise the responses to determine those which may impact our proposal. Any feedback which could impact our proposal has to be looked at in detail.

We will now produce a Consultation Response document which summarises the consultation and the themes arising from the categorisation which will inform the development of our proposals. Following Civil Aviation Authority approval of the categorisation, our proposal will then be refined based on the feedback themes to produce a Final Option Appraisal.

Stage 1A

At Stage 1A, Glasgow Airport participated in an assessment with the Civil Aviation Authority (CAA) to discuss the Statement of Need and to enable the CAA to consider whether the proposal falls within the scope of the formal airspace change process.

• Statement of Need
• Assessment meeting minutes

Stage 1B

At Stage 1B, Glasgow Airport developed a set of Design Principles through engagement with identified stakeholder representatives. The Design Principles provide high-level criteria that the proposed airspace design options should meet. They also provide a means of analysing the impact of different design options and a framework for choosing between or prioritising options.

• Stage 1B Design Principles Submission Report

Stage 2A

Stage 2A requires Sponsors to develop and assess options for the airspace change. In Stage 2A, the Sponsor develops a Comprehensive List of Options that address the Statement of Need and that align with the Design Principles from Stage 1. Those options are then shared with stakeholder representatives (the same ones engaged on the Design Principles). Feedback from the engagement was then used to generate further options where feasible. Finally, all options were qualitatively assessed against the Design Principles and a Design Principle Evaluation (DPE) was produced. Glasgow Airport’s Comprehensive List of Options was then shortlisted before progressing to Stage 2B.

• Stage 2A Main Document

Stage 2B

Stage 2B requires the Sponsor to carry out an Initial Options Appraisal (IOA) of the airspace change options which proceed from Stage 2A. The appraisal described the options, explaining the methodology used to assess each option and the IOA outcome. Following this the document explained, based on the IOA, which options have been taken forward to Stage 3 and the preferred option(s).

• Initial Options Appraisal

Stage 3

Stage 3 is when we carry out public consultation, which took place from 20 October 2025 – 25 January 2026. This consultation is based on our Full Options Appraisal which assesses our chosen option. We gather feedback on this option and use that feedback to help further develop and refine the proposal.

• Full Options Appraisal

We followed a data led approach to inform the proposal shared during public consultation. We started by removing all the routes around Glasgow Airport and then flooding the airspace with 1000s of potential flight paths. These were then all assessed against our Design Principles, which were agreed with our stakeholders in Stage 1, and 30 options were selected. We worked with our stakeholders again in Stage 2 to refine the list further and re-assess those options against a number of criteria and our current flightpaths. This provided us with a shortlist to assess against operational and environmental categories required by the CAA’s Airspace Change Process (CAP1616), which in turn provided us with the option we are currently consulting on.  

It is important to note that at every stage, we have followed what the data recommended in terms of meeting our own objectives and those of the Airspace Modernisation Strategy, CAP1616 and Government policies. During Stage 3, we sought feedback on our proposed option to help us refine our proposal further. You can see the responses received during consultation on our portal here. All feedback will now be read, and we will collate, review and categorise the responses to determine those which may impact our proposal. Any feedback which could impact our proposal has to be looked at in detail.

We will produce a Consultation Response document which summarises the consultation and the themes arising from the categorisation which will inform the further development of our proposals.

This Airspace Change Proposal is not linked to growth and instead is driven by the UK Government’s requirement for 18 UK airports to modernise their airspace. Whilst Glasgow Airport has been transparent in its ambition to grow (targeting growth of around 5% per year), this growth is not dependent on our Airspace Change Proposal.

When assessing noise for an Airspace Change Proposal, we are required to follow UK Government noise policy and the requirements of CAP1616.

Some communities have asked whether the noise metrics we use are calculated as part of the CAP1616 process account for the World Health Organisation’s guidelines around noise.

The primary noise metrics required by UK Government policy and the Civil Aviation Authority’s airspace change process look at the adverse noise impacts across the busy 92 day summer period.

The thresholds for noise as set out in these policies are based on the Civil Aviation Authority’s Survey of Noise Attitudes (SoNA), which was a UK-based noise study. Information from this study has been adopted into the UK specific metrics and thresholds.

The World Health Organisation’s guidance looks at the adverse noise impacts across a full year, taking into account the quieter periods. The World Health Organisation guidance is based on international studies, and within that guidance it suggests that country specific data and exposure–response curves are applied whenever possible to assess the relationship between noise and annoyance and therefore the UK policy is in line with World Health Organisation guidelines.

The noise assessment is based around the CAP1616 primary and secondary noise metrics.

Primary noise metrics:
Noise metrics are generated based on a 92-day summer period from 16 June to 15 September inclusive. For the purposes of the noise modelling, a modal split of Runway 05 being used 23% of the year, and Runway 23 being used 77% of the year has been applied.

LAeq16hr (daytime noise) and LAeq8hr (night-time noise) noise exposure data is what is assessed to determine impacts.

LAeq is way of measuring fluctuating sound levels over a specific period (see the time period shown in brackets), and representing it as a single, equivalent continuous sound level in decibels. The key thresholds set by Government policy for this are Lowest Observable Adverse Effect Levels (LOAEL), which are the levels at which adverse effects on health and quality of life can be detected.

These levels are based on the daily average movements that take place in the 16-hour period (07:00-23:00 local time) or 8-hour period (23:00-07:00) during the 92-day period 16 June to 15 September inclusive. The levels vary depending on the time of day:

• During the day (7am-11pm) the LOAEL threshold is 51 decibels LAeq(16 hours)
• Overnight (11pm-7am) the LOAEL threshold is 45 decibels LAeq(8 hours)

This metric is the measure of noise exposure adopted by UK Government for the purposes of considering adverse effects from aircraft noise. It forms the basis of the UK Government’s policies in relation to aircraft noise.

There’s more information about the primary noise metrics on page 80 of our Main Consultation Document.

Secondary noise metrics:
N60 and N65 are what is calculated for secondary noise metrics. These metrics respectively describe the number (N) of aircraft noise events above a noise level of 60 decibels LASmax in the night-time period and 65 decibels LASmax for the daytime period. These are event-based metrics, which can be used to better understand the number of noise events that occur and their location.

LASmax is the maximum A-weighted noise level experienced during an individual aircraft overflight.
N65 and N60 contours have been generated for the baseline and for the proposed option. These contours have been used to calculate the total population within the contour and the area of the contour.

You can find more information about these from page 81 of our Main Consultation Document.

When assessing noise for an Airspace Change Proposal, we are required to follow UK Government noise policy and the requirements of CAP1616. When considering primary metrics, Government policy defines the 51 decibel daytime and 45 decibel nighttime LAeq contour as the threshold used to measure adverse effects from noise exposure (see above for more information about this).

Information from the LAeq contour is then input into the Department for Transport’s TAG workbook which looks to monetise the benefits/impacts to changes in noise exposure. There’s more information about the primary noise metrics on page 80 of our Main Consultation Document.

Secondary metrics, including ‘number above contours’ (N60/N65) and overflight contours are also generated for the with and without airspace change scenarios. You can find more information about these from page 81 of our Main Consultation Document.

When considering noise impacts, CAP1616 explains “the CAA will weigh the outcomes from ‘primary’ metrics over ‘secondary’ metrics. Primary metrics will be those that are used to quantify significant noise impacts, such as WebTAG outputs*. Secondary metrics will be those that are not being used to determine significant impacts, but which are still able to convey noise effects, such as N65 contours and Lmax levels. While not a noise metric, overflight contours will be a secondary metric for the purposes of decision-making.”

*WebTAG is the Department for Transport’s suite of guidance on how to assess the expected impacts of transport policy proposals and projects. The TAG noise is a tool which assesses the impact of changes in noise exposure and can be used to monetise certain aspects of the noise impact. LAeq16hr (daytime noise) and LAeq8hr (night-time noise) noise exposure data form the input into TAG.

All noise and overflight modelling carried out as part of the detailed noise assessment for this Airspace Change Proposal takes terrain into account. Ordnance Survey terrain data is incorporated directly into the model. Within the model, aircraft altitude is based on the airport’s airfield elevation. This is 26ft for Glasgow Airport.

The modelling then bases the climb or descent of aircraft on Glasgow Airport’s radar data, to reflect the actual operations of aircraft departing from and arriving at the airport.

To account for terrain in the model, receivers are positioned at their actual local ground level. This means that in higher-elevation areas, the model has receivers higher up and therefore closer to the aircraft overflying that area.

This approach ensures that the detailed noise modelling in the Full Options Appraisal accurately accounts for how noise is experienced in locations with varying terrain.

The typical aircraft altitudes shown for a specific location within the interactive maps are based on actual climb and descent profiles from Glasgow Airport with a buffer applied to account for a margin of error.

When determining this buffer, we’ve considered lots of information including variation in terrain, the potential for calculated error within the noise modelling, what is considered a perceptible change in noise, and the variation of current performance of aircraft departing and arriving from Glasgow Airport. This means that the altitude bands shown do account for the typical variation in local terrain around Glasgow Airport.

However, please note that the information presented is indicative as it is based on a typical flight for the two aircraft types. The rate that aircraft climb varies depending on lots of factors such as the wind, air temperature, weight of aircraft and aircraft type. Aircraft descending to land follow a more consistent descent profile, however there can still be some variation.

The ambient background environments available in the sound demonstrations have been selected to cover the typical range of ambient noise levels experienced in Scotland. This is based on the results of the National Noise Incidence Study 2000/2001, which measured and classified the distribution of environmental noise levels across the UK by surveying a representative sample of locations, including urban, suburban, and rural areas, to establish typical background sound levels experienced by the population.

There is more information about how tranquillity has been assessed, and the outcome of the assessment, in our Main Consultation Document on Page 103. The document can be accessed here.

There is more information about how tranquillity has been assessed, and the outcome of the assessment, in our Main Consultation Document on Page 107. The document can be accessed here.

Health effects from noise are assessed by analysing changes in LAeq noise metrics, which are the primary metrics required under CAP1616 and UK Government policy.

The outcomes of this noise analysis are then input into the Department for Transport’s TAG noise workbook. The TAG methodology applies evidence-based probabilities to estimate the likely health impacts across the affected population, including annoyance, sleep disturbance, acute myocardial infarction, dementia, and stroke. For each decibel change in average noise level, the workbook assigns a monetary value to the change in health outcomes, allowing for a consistent and transparent comparison of different airspace change options.

There is more information about the noise and TAG methodology in our Main Consultation Document on Page 80 and the results of the assessment are summarised on page 82 onwards. The document can be accessed here.

Within the Full Options Appraisal, there is further detailed information about the noise assessments undertaken. Information about the noise assessment methodology can be found from page 88 onwards and the full assessment outcomes for the Consultation option are detailed from page 345 onwards. The document can be accessed here.

As part of Stage 3 of the CAP1616 process, Glasgow Airport has undertaken safety assessments on the proposals in accordance with Civil Aviation Authority approved Safety Management Systems and processes. This involved testing the designs within Air Traffic Control simulators to understand how the airspace could be safely operated in future whilst integrating all arriving and departing traffic from Glasgow Airport and the wider airspace. There were also airline simulators where the flyability of some elements of the designs were tested to understand any technical refinements needed to the flight procedures. The outcomes of this work were used to guide the development of the proposals that were then assessed as part of the Full Options Appraisal ahead of this consultation.

This safety work forms part of the first stages of assessing the proposals with further, very detailed, safety assessments required as part of the Airspace Change Proposal submission at Stage 4 once the final design has been determined. All safety justification must be reviewed and approved by the Civil Aviation Authority ahead of implementation.