NMB activities

The consolidated First Term Workplan was approved and adopted by the NMB in 2017, incorporating activities arising from the recommendations of the Arrivals Review as well as a number of departure activities identified through engagement with the NMB. In total, 20 activities were identified in the workplan and were prioritised based on guidance developed by the NMB.

This section provides an update on a number of completed and ongoing NMB noise reduction initiatives. Further information can be found in the NMB First Term Report and the NMB annual report 2019.

This activity was initiated in 2017 and has the potential to verify whether meaningful noise reductions for communities can be achieved using Performance Based Navigation (PBN) technology during the night when noise sensitivity is high.

In accordance with CAA’s new CAP1616 guidance, GAL submitted a Trial Submission Pack in late September 2019. The pack comprised details of the trial engagement, industry consultation, Instrument Flight Procedure (IFP) designs, environmental and safety assessments, trial procedures and activity timescales.

This information is published on the CAA Portal. Since submission, Gatwick has been informed by the CAA that, due to reprioritisation of their work by the new Department for Transport, a decision on the RNN Trial will be delayed from the planned March 2020 start date. Gatwick is awaiting a clearer indication of likely timescales for assessment of the RNN trial by the CAA.

What is the reduced night noise trial?

The RNN trial is a proposal, through the Noise Management Board (NMB) Workplan, to increase the height of low flying aircraft so that the noise they make on the ground below is reduced. This trial will not enable any more aircraft to fly at night than is currently allowed and nobody will be newly overflown.

Sometimes arriving aircraft fly significantly lower or make significantly more noise than other similar aircraft. These aircraft tend to cause the most disturbance because they can be noticeably louder than other similar aircraft. The aim of the trial is to reduce the number of these aircraft known as ‘outliers’.

What are the key details of the trial?

The trial will run for six months in total, planned to start in March 2020. The trial will run from 01:30 – 05:00 (local time).

Mobile noise monitors will capture aircraft noise before and during the trial in order to assess noise performance. These are placed in locations under some of the RNN routes.

The trial will use navigation technology called Performance Based Navigation (PBN) – will this lead to a concentration of flights?

PBN is a means of navigation that allows the aircraft to fly accurate routes. One feature of PBN is that, when used for arrivals, it can allow the aircraft to be carefully controlled so it descends more slowly, and in a quieter and more efficient manner.

PBN routes are associated with more concentrated flight paths. This is due to the higher accuracy of the technology compared to current procedures as aircraft approach the airport. To minimise the impacts of this, multiple trial routes have been designed to ensure the distribution of noise. The routes are all placed within existing arrival swathes.

There will be 16 published PBN arrival routes. This will allow for four arrival routes to each runway end (westerly and easterly) and both runways (southern and northern). For further information on Gatwick’s aircraft operations, please visit our noise portal.

Where are the trial routes?

The proposed trial routes are shown below. Arrival routes to the Southern runway are in yellow and to the Northern runway in blue. The “overflight cones” as defined by the Civil Aviation Authority (CAA) are shown in white.

Each arriving aircraft will use the most appropriate route to reach the runway, which is defined by the aircraft’s arrival direction, ie from the South East or West.

Trial routes (blue and yellow lines) overlaid on the existing traffic patterns

The trial routes have been designed with the aim of minimising concentration and dispersing arrivals. No trial routes will be outside of the existing swathe and therefore no new communities will be impacted by noise from this trial.

Detailed route maps are shown below using the same key: arrival routes to the Southern runway are in yellow and to the Northern runway in blue.

Detail of westerly arrival routes

Details of easterly arrival routes

Why didn’t you take the opportunity to try new routes away from the existing ones?

At night, aircraft join the Gatwick Instrument Landing System (ILS) at 10NM from touchdown. This is specified by the Department for Transport (DfT). Some residents have asked why the trial doesn’t take the opportunity to try a different ILS joining point to move aircraft away from the populated area of Tunbridge Wells on westerly approaches.

The RNN trial is about reducing the number of ‘outlier’ noise events by lifting aircraft in the existing swathe of arrivals traffic higher so that they make less noise on the ground. If the trial overflies new areas of population then we will not be able to validate the ‘before’ and ‘after’ effect of the routes.

Changes to routes or the night-time joining point would also require Gatwick to develop a full Airspace Change Proposal as set out in the CAA document CAP1616.

Further information on Gatwick’s aircraft operations.

Why can’t the benefits of PBN be assessed through computer simulation?

Noise models can be used to predict the noise impact of aircraft. However, these are not considered accurate beyond about 12 NM (Nautical Miles, approx. 22 km) from an aircraft’s touchdown. The trial procedures are expected to have a positive noise impact in the region of 10 – 20 NM from touchdown which is beyond this range.

The trial will allow data to be recorded on mobile noise monitors which are placed around the airport, and up to around 18 NM away from the airport. Noise from aircraft before and during the trial will be recorded and analysed.

Please see the Trial Submission Pack on the CAA airspace change page which contains technical information on the noise analysis undertaken for this trial.

Why is the trial taking place at night?

The trial is taking place during the night because airline and Air Traffic Control (ATC) procedures are best trialled when the airport is less busy, and traffic volumes are low allowing the procedure to be more easily managed. At this time, ambient noise is also reduced which allows the noise from quieter aircraft to be measured at distances further away from the airport.

The trial will not identify routes for use in future airspace design, nor will it be used to provide evidence for a revised night flight regime. The objective of the trial is to assess the extent to which PBN can achieve noise benefits for arriving aircraft.

Under what circumstances will the trial be suspended?

The trial may be suspended for operational reasons, such as if there are unexpectedly high levels of traffic or the need for weather avoidance. In this case, ATC will revert to their usual procedures. The trial would then resume later that night or the following night.

The trial may also be suspended if, after analysis of initial results, it looks like it might not have achieved the benefits expected.

Please see the Trial Submission Pack which contains information on procedures for suspending this trial.

How many flights will be involved in the trial?

Nightly average flights will follow a similar pattern to today which range from about two arrivals in low traffic months to 24 in high traffic months. The following table shows the averages from Jan 2017 – Aug 2019, and the maximums identified in those months.

What factors will affect the number of arrivals participating in the trial?

The traffic figures presented as part of the analysis for the trial reflect growth in air traffic since 2017 and the impact of seasonal variations on the number of night arrivals at the airport. On average, the number of night arrivals is higher in summer than in winter months due to the demanding summer schedule.

Monthly figures can be skewed by unusual events such as industry strikes or weather. In these scenarios, it’s commonplace for scheduled daytime arrivals to fall into the night because the disruption causes them to run late. This is reflected in the RNN analysis. In July and August 2019, poor weather led to significant delays across several days. There were 4 nights with greater than 30 flights, all of which fell on days with bad weather.

In any night where there are particularly high volumes of arrivals, NATS will temporarily suspend the trial and return to vectoring procedures. The trial would resume once traffic levels reduced to a manageable level. See “Under what circumstances will the trial be suspended?” for further information.

Who approves the trial?

The trial will be approved by the CAA. It is being prepared according to the CAA requirements for trials described in CAP1616.

How will stakeholders be engaged?

Gatwick has undertaken comprehensive engagement with both industry and local communities through representatives on the NMB, Gatwick Airport Consultative Committee, Flight Operations & Performance Safety Committee and Noise and Track Monitoring Advisory Group throughout all stages of the development of the trial, and this will continue up to, during and after the trial.

How can I complain during the trial?

Throughout the trial period, members of the public will have access to existing platforms for submitting complaints and enquiries to Gatwick Airport. Complaints can be made online, by a mobile app, by phone or by post.

Any noise complaints submitted directly to the CAA through its Airspace Change Portal will be redirected by the CAA to GAL for review.

There will be no limit to the number of complaints and enquiries that can be submitted by an individual or an organisation during the trial period. All complaints and enquiries will be handled in accordance with GAL’s extant complaints external complaints handling policy.

We will continue to update these groups as to the progress of the trial, as well as publishing information on our website.

What are the next steps from September 2019 to the start of the trial?

Gatwick has to follow CAA guidance (CAP1616) for the process of conducting a trial and the CAA must approve the trial. CAP1616 requires Gatwick to prepare a trial submission pack that describes the trial plans and supporting analysis.

Gatwick submitted the trial submission pack at the end of September for the CAA’s review and the CAA will publish its review on their website. If approval is given, Gatwick Airport will engage with local communities in order to communicate the trial commencement and process. Please read the Trial Submission Pack for further details.

What will happen after the trial?

Aircraft will go back to flying the arrival routes in the way they do today. The evidence from the trial will be examined by Gatwick Airport and its stakeholders and outcomes will be reported to industry and community.

The trial will not be used to identify new routes for future airspace design or increase capacity. Nor will the trial be used to introduce airspace change without consultation.

NMB activities

FOPP modification

Reduced night noise trial