AIRBORNE AIRCRAFT NOISE CONTOURS 2017 · 2.2 Traffic Distribution by Aircraft Type The basis for the 2017 noise contours are the actual movements during the 92 day summer period,

Report to George Best Belfast City Airport Sydenham By-Pass Belfast BT3 9JH A11131-R01-DR-Rev1 15 November 2017

GEORGE BEST BELFAST CITY AIRPORT

AIRBORNE AIRCRAFT NOISE CONTOURS 2017

A11131-R01-DR-Rev1 15 November 2017 2

Bickerdike Allen Partners LLP is an integrated

practice of Architects, Acousticians, and Construction

Technologists, celebrating over 50 years of

continuous practice.

Architects: Design and project management services

which cover all stages of design, from feasibility and

planning through to construction on site and

completion.

Acoustic Consultants: Expertise in planning and

noise, the control of noise and vibration and the

sound insulation and acoustic treatment of buildings.

Construction Technology Consultants: Expertise

in building cladding, technical appraisals and defect

investigation and provision of construction expert

witness services.

This report and all matters referred to herein remain confidential to the Client unless specifically authorised otherwise, when reproduction and/or publication is verbatim and without abridgement. This report may not be reproduced in whole or in part or relied upon in any way by any third party for any purpose whatsoever without the express written authorisation of Bickerdike Allen Partners. If any third party whatsoever comes into possession of this report and/or any underlying data or drawings then they rely on it entirely at their own risk and Bickerdike Allen Partners accepts no duty or responsibility in negligence or otherwise to any such third party. Bickerdike Allen Partners hereby grant permission for the use of this report by the client body and its agents in the realisation of the subject development, including submission of the report to the design team, contractor and sub-contractors, relevant building control authority, relevant local planning authority and for publication on its website.


Contents Page No.

1.0 Introduction .................................................................................................................................. 4

2.0 Aircraft Operations ...................................................................................................................... 4

3.0 INM Model ................................................................................................................................... 9

4.0 Noise Contours ............................................................................................................................ 11

5.0 Summary ..................................................................................................................................... 13

Figures

Figure A11131/R01/01: Initial Departure Routes

Figure A11131/R01/02: Daytime Summer Noise Contours 2017 – 54 to 69 dB LAeq,16h in 3 dB steps

Figure A11131/R01/03: Comparison of 2017 and DoE Indicative Daytime Noise Contours – 63 dB LAeq,16h

Figure A11131/R01/04: Comparison of 2017 and DoE Indicative Daytime Noise Contours – 60 dB LAeq,16h

Figure A11131/R01/05: Comparison of 2017 and 2016 Daytime Noise Contours – 63 dB LAeq,16h



Appendices

Appendix 1: Glossary of Acoustic and Aviation Terminology

Appendix 2: George Best Belfast City Airport Contour Validation – Noise

Appendix 3: INM Substitution List


1.0 INTRODUCTION

Bickerdike Allen Partners LLP (BAP) have been retained by George Best Belfast City Airport

(GBBCA) to produce airborne aircraft noise contours for the 92 day summer period (16th June

to 15th September inclusive) in 2017.

Noise contours have been predicted using the actual aircraft movements over the 92 day

summer period and the Federal Aviation Administration prediction methodology, the

Integrated Noise Model (INM) version 7.0d. This methodology has been validated for the most

common aircraft types operating at the airport, using results from the Noise Monitoring

Terminals (NMTs) installed at GBBCA.

Noise contours have been produced annually at GBBCA for several years. Those for 2016 were

reported in BAP’s report Ref: A11019-R01B-DR, dated 10th January 2017.

This report sets out the assumptions used in the computation of the 2017 contours. The

resulting contours are also included, as are contour areas and population counts for the key

noise exposure contour band values.

A glossary of acoustic and aviation terms can be found in Appendix 1. Appendix 2 contains

details of BAP’s validation exercise with respect to noise. Appendix 3 details the INM types

used to model the aircraft at GBBCA.

2.0 AIRCRAFT OPERATIONS

2.1 General

The aircraft movement data, provided by GBBCA, has been assessed in relation to aircraft

type, departure and arrival route, flight profiles and runway usage to enable input into the

noise computation program, the Integrated Noise Model (INM). This section of the report

describes how this briefing information has been compiled in a form suitable for analysis

purposes.

2.2 Traffic Distribution by Aircraft Type

The basis for the 2017 noise contours are the actual movements during the 92 day summer

period, 16th June to 15th September inclusive. This is the usual period taken when producing

noise contours in the UK and usually represents a worst case as airport traffic generally peaks

in the summer due to holidays.


The actual movements are a combination of the passenger movements, any freight

movements, and the non-commercial movements which include any training flights. Detailed

information was provided for all aircraft movements during the 92 day period in 2017.

Although a small proportion of movements occur early in the morning between 6:30 and 7:00

or late in the evening between 23:00 and 23:30 over the 92 day period, for the production of

the noise contours all movements have been assumed to take place within the “daytime

period” of 07:00 to 23:00.

The actual movements in 2017 also include 40 movements by helicopters. Historically,

helicopters have not been modelled at GBBCA. They typically comprise less than 1% of the

total movements, and this was also the case in 2017, therefore they have continued to be

omitted. Their continued omission is not considered significant to the overall contours and

maintains consistency with previous contouring.

The INM software includes noise information for many common aircraft types, but as with all

noise modelling software, it does not include every aircraft type. This means that substitutions

are required, where an alternative aircraft type is used to model the actual type. For larger

aircraft this generally does not involve a change but for the smaller types, and in particular the

general aviation aircraft, substitutions occur. Where INM has no guidance, an aircraft type has

been assigned based on the aircraft size and engine details. Full details of the INM aircraft

types used are given in Appendix 3.

Table 1 shows the aircraft movements in summer 2017 by INM type, as well as the

movements for summer 2016 for comparison purposes.


Aircraft Type INM Designator 2017

Movements 2016

Movements

Airbus A319 A319-131(1) 635 6.3% 634 5.4%

Airbus A320 A320-211(1) 1,420 14.1% 1,662 14.2%

Avions de Transport Regional ATR-72

DO328 n/a(2) n/a(2) 66 0.6%

Beechcraft - twin turboprop CNA441 23 0.2% 19 0.2%

British Aerospace BAe 146-200 BAE146 164 1.6% n/a(2) n/a(2)

British Aerospace BAe 146-300 BAE300 n/a(2) n/a(2) 127 1.1%

British Aerospace Jetstream 32 DO228 20 0.2% n/a(2) n/a(2)

British Aerospace Jetstream 41 SF340 131 1.3% n/a(2) n/a(2)

Cessna Citation Jet CNA500 38 0.4% 54 0.5%

De Havilland Dash 8-400 DHC6/SD330(1) 7,214 71.7% 8,054 68.8%

Embraer EMB-170-200 EMB175/737500(1) 167 1.7% 194 1.7%

Embraer EMB-190-100 EMB190 24 0.2% n/a(2) n/a(2)

Fokker 70 F10062/737800(1) n/a(2) n/a(2) 184 1.6%

Let L-410 DHC6/SD330(1) n/a(2) n/a(2) 534 4.6%

Miscellaneous business jet CNA500 94 0.9% 53 0.5%

Miscellaneous prop, single engine GASEPF 25 0.2% 28 0.2%

Miscellaneous prop, twin engine BEC58P 19 0.2% 13 0.1%

Pilatus PC-12 CNA208 29 0.3% 14 0.1%

Other (less than 10 movements) Various 57 0.6% 74 0.6%

Total 10,060 100% 11,710 100%

(1) Aircraft type modified based on results of a validation exercise. (2) n/a is shown where a type operated less than 10 times in one of the years.

Table 1: Aircraft Types used in INM for 2017 and 2016 Summer Contours


In summary, the overall movement numbers have decreased by around 14% from 2016 to

2017. The commercial aviation still consists mainly of twin engined turboprop aircraft (e.g.

Bombardier Dash 8-Q400) and twin engined turbofan aircraft (e.g. Airbus A320 family). The

majority of the decrease in overall movements is due to the decrease in Dash 8-Q400

movements in 2017 and the Let L-410 ceasing to operate, leading to an overall decrease in the

proportion of turboprop movements. Airbus A320 movements have also decreased slightly,

while movements by the Airbus A319 have remained similar.

2.3 Flight Tracks

A validation exercise was undertaken in 2011 to validate the flight tracks used in the INM

software. The details of this exercise are shown in Appendix B of BAP’s report

Ref: A9443-R01-NW dated November 2011. The resulting main departure tracks are shown in

Figure 01 and have been used for the 2017 contours as there have been no changes to the

published routes since 2011.

2.4 Traffic Distribution by Route

The overall split of movements by runway during the 2017 summer period is given in Table 2,

and is compared with that for 2016. For the modelling, the actual runway usage for each

individual movement was used.

Runway 2017 Movements 2016 Movements

Arrivals Departures Arrivals Departures

04 1,222

(24.3%)

1,515

(30.2%)

1,086

(18.5%)

1,335

(22.8%)

22 3,815

(75.7%)

3,508

(69.8%)

4,770

(81.5%)

4,519

(77.2%)

Table 2: Summer 2017 and 2016 Runway Usage

For arrivals there has been an increase of around 6% in activity on runway 04 compared to

2016, with a corresponding decrease in activity on runway 22. For departures there has been

an increase of around 7% in activity on runway 04 compared to 2016, with a corresponding

decrease in activity on runway 22.


For each runway there is a single modelled arrival route, which follows the runway centreline.

There is one modelled initial departure route on runway 22, but four modelled initial

departure routes on runway 04, as shown in Figure 01. The method of determining the split of

aircraft between the routes from runway 04 takes into account both aircraft type and

destination. Where the destination is in Scotland or in Northern Europe (Iceland, Norway, etc.)

the initial route heading in a north easterly direction is used. The remaining traffic is split

amongst the three routes which turn south, the particular route depending on the distance at

which the aircraft type involved is expected to have achieved one of a set of specific altitudes,

as required by the airport’s noise abatement procedures. These altitudes are 1,500 ft for small

propeller aircraft (maximum takeoff weight of up to 13,000 kg); 2,000 ft for large propeller

aircraft; and 3,000 ft for jet aircraft.

2.5 Dispersion

For departures, as aircraft do not follow precisely the routes they are assigned to, the INM

software was used to generate a mean track for each of the five initially distinct routes and

these mean tracks were then dispersed as described below.

The dispersion model has the common assumption that there are five "dispersed" tracks

associated with each departure route; these comprise the mean track of each route and two

sub-tracks either side. The allocation of movements adopted for the 2017 contours to each

track is as follows:

53.3% departures along the main track;

22.2% departures split equally along two inner sub tracks either side of the main track

and offset by a distance of 1.355 standard deviations;

1.15% departures split equally along two outer sub tracks either side of the main track

and offset by a distance of 2.71 standard deviations.

This dispersion model has been used in the INM software, which generates the sub-tracks with

distances supplied by the user. The distances and percentages used have been determined by

BAP from analysis of similar activity at other airports.


2.6 Flight Profiles

For departure movements the INM software offers a number of standard flight profiles for

most aircraft types, particularly for the larger aircraft types. These relate to different

departure weights which are greatly affected by the length of the flight, and consequently the

fuel load. In the INM software this is referred to as the stage length. The stage length occurs in

increments of 500 nmi up to 1,500 nmi and then increments of 1,000 nmi. The INM software

assumes all aircraft take off with a full load irrespective of stage length. As the stage length

increases, the aircraft has to depart with greater fuel, and so its flight profile is slightly lower

than when a shorter stage length is flown.

For the 2017 contours, destination airports were given with the actual movements. Stage

lengths have been assigned, where INM offers the option, based on the distance of these

airports from GBBCA.

3.0 INM MODEL

3.1 General

All contours and population counts have been determined using the Integrated Noise Model

(INM) version 7.0d software and a postcode population database. The population data has

been derived from census information and has been supplied by CACI Ltd. The latest available

database has been used, which is the 2017 database.

The Integrated Noise Model (INM) software evaluates aircraft noise in the vicinity of airports

using flight track information, aircraft fleet mix, standard or user-defined aircraft profiles and

terrain. The INM software is used to produce noise exposure contours as well as predict noise

levels at specific user-defined sites.

3.2 Assumptions

GBBCA data relevant to the INM study is taken from the latest edition of the UK Aeronautical

Information Package.

As with all modelling programs not every aircraft type is specifically included in the INM

software and substitutions are required. Details regarding aircraft types are given in Section

2.2 and Appendix 3.

A 3.0° approach angle is used for all aircraft and the ground topography is assumed to be flat.

The INM default headwind of 14.8 km/h is assumed.


The INM version 7.0d has two options for lateral attenuation, one relates to acoustically soft

ground such as grassland and the other hard ground such as built up areas and water. Due to

the presence of the Lough and the other hard surfaces around GBBCA hard ground was

assumed for the contours produced before 2010. This had the effect of reducing the

attenuation of noise from propeller driven aircraft but did not affect jet aircraft. The different

approach to lateral attenuation based on the aircraft type is given in the relevant standards

which aim to reflect actual performance.

For the 2010 contours onwards, acoustically soft ground has been assumed. This followed

advice received from the Civil Aviation Authority on the lateral attenuation to use. The same

assumption has again been used for the 2017 contours.

For some aircraft types it has been necessary to modify the standard INM assumptions. This

was also done for the earlier contours. The installation of the permanent Noise Monitoring

Terminals (NMTs) at GBBCA was completed in 2008 so for the 2009 contours onwards a

significant amount of measured noise data has been made available. Results from the period

September 2016 to October 2017 have been used for the 2017 validation exercise to review

the INM assumptions for the most common aircraft types operating at GBBCA.

The 2017 validation exercise found that modifications were required for several aircraft types,

to better model their operations at GBBCA. These included types such as the Bombardier

Dash 8-Q400 for which the INM does not contain specific data. The result is that the modelled

noise characteristics of these aircraft have been adjusted by modifying the INM aircraft used

and/or the actual movement numbers flown during the period when producing the contours.

These adjustments are detailed in Table 3 below.

Aircraft Type Default INM

Type

Modification to INM Assumptions

Departures Arrivals

Airbus A319 A319-131 A319-131 × 1.4 A319-131 × 0.7

Airbus A320 A320-211 A320-211 × 1.1 A320-211

Bombardier Dash 8-Q400 - DHC6 × 0.8 SD330 × 1.4

Embraer E175 EMB175 737500 × 1.3 EMB175 × 1.2

Table 3: Modifications to INM Assumptions used for 2017 Contours

These modifications to INM assumptions are similar to those used for the 2016 contours. The

arrival multiplier for the Airbus A319 on arrival has been reduced by 0.1 compared to 2016 to

account for quieter measured noise levels. The Fokker 70 and the Let 410 which previously

featured in the annual validation have not been validated in 2017 as they no longer operate in

significant numbers. Full details of the 2017 validation exercise are given in Appendix 2.


4.0 NOISE CONTOURS

Noise contours, in terms of the index LAeq,16h, have been produced for the 16 hour daytime

period, 07:00 to 23:00; although they also include the movements that occurred between

06:30 and 07:00 and the small number that occurred between 23:00 and 23:30. They are

based on the actual movements for the summer 92 day period in 2017. Daytime 16 hour

contours of this type, shown in Figure 02, have been used for many years in the UK to assess

noise impact. Contour areas are given in Table 4 where they are compared with the

corresponding contour areas for summer 2016.

Figure 03 shows a comparison between the 63 dB LAeq,16h daytime contour based on the 2017

movements and the DoE indicative contour resolved in 1997. The 2017 contour is shorter than

the indicative contour, but is very slightly wider in some locations. There are no residential

properties within the 2017 contour.

Figure 04 shows a comparison between the 60 dB LAeq,16h daytime contour based on the 2017

movements and the DoE indicative contour. The 2017 contour is shorter than the indicative

contour, but slightly wider in some locations. There are no residential properties within the

2017 contour. Figures 05 to 07 show comparisons between 2017 and 2016 for the 63, 60 and

57 dB LAeq,16h contours respectively.

Contour Level

(dB LAeq,16h)

Area of Daytime Air Noise Contours (km2) Change in Contour Area

2017 vs. 2016 2017 2016

54 6.07 7.17 -15%

57 3.02 3.66 -17%

60 1.51 1.80 -16%

63 0.83 0.96 -14%

66 0.49 0.56 -13%

69 0.30 0.34 -12%

Table 4: Comparison of 2017 and 2016 Noise Contour Areas

Table 4 shows that the 2017 contour areas are smaller than those for the 2016 contours, by an

average of 15%. Figures 05 to 07 show that the 2017 contours are similar in shape to the 2016

contours.

The decrease in contour area from 2016 to 2017 is primarily due to the 14% decrease in total

aircraft movements. The change in validation for 2017 also causes a small reduction in contour

area, due to quieter measured arrival noise levels for the Airbus A319.


4.1 Population Counts

Population counts for the 2017 and 2016 LAeq,16h daytime contours are given in Table 5 and

Table 6 below.

Contour Level (dB LAeq,16h) 2017 Population 2016 Population

54 12,097 15,530

57 2,879 4,977

60 0 32

63 0 0

66 0 0

69 0 0

Table 5: Comparison of 2017 and 2016 Population Counts – Cumulative Totals

Year Population by Contour Band (dB LAeq,16h) Total

> 69 69 – 66 66 – 63 63 – 60 60 – 57 57 – 54

2017 0 0 0 0 2,879 9,218 12,097

2016 0 0 0 32 4,945 10,553 15,530

Table 6: Comparison between 2017 and 2016 Population Counts

Table 5 and Table 6 show that there are no people exposed to 60 dB LAeq,16h or higher in 2017,

compared to 32 people within the 63 – 60 dB LAeq,16h contour band in 2016. The population

within the 57 to 60 dB LAeq,16h band has decreased by 2,066. Proportionally, this is greater than

the associated decrease in contour area. As the local population is not evenly distributed over

the contour area, changes in contour area can have no effect on the population contained in a

band or significant effects depending on the location of the area in question. The population

within the 54 to 57 dB LAeq,16h contour band has also decreased.


5.0 SUMMARY

LAeq,16h noise contours and the associated population counts have been produced, based on

the actual movements during the 92-day summer period in 2017.

The 2017 contours extend slightly outside the DoE indicative contours in a few places, but lie

well inside in most places. No residential properties are located in the 2017 60 or 63 dB LAeq,16h

contours.

The 2017 LAeq,16h contours are similar in shape, but smaller by an average of 15%, compared to

the 2016 LAeq,16h contours. This is primarily attributed to the 14% decrease in the total number

of movements. The total population within the 2017 contours is smaller than that within the

2016 contours, due to the contours being smaller in size.

Duncan Rogers David Charles Peter Henson

for Bickerdike Allen Partners Associate Partner

LEGEND:

Initial Departure Routes

This drawing contains Ordnance Survey data © CrownCopyright and database right 2017.

DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:

121 Salusbury Road, London, NW6 6RGEmail: [email protected] T: 0207 625 4411www.bickerdikeallen.com F: 0207 625 0250

REVISIONS

Belfast City AirportNoise Contours

Initial Departure Routes

DR NW

October 2017 1:125000@A4

A11131/R01/01

54

LEGEND:Noise Contours,54 to 69 dB LAeq,16h in 3 dB steps


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS


2017 Summer Daytime Noise Contours

DR NW

October 2017 1:50000@A4

A11131/R01/02

LEGEND:2017 Noise ContourDoE Indicative Noise Contour


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS


Comparison of 2017 and DoE Indicative Summer Daytime Noise Contours63 dB L

DR NW

October 2017 1:50000@A4

A11131/R01/03

Aeq,16h

LEGEND:2017 Noise ContourDoE Indicative Noise Contour


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS


Comparison of 2017 and DoE Indicative Summer Daytime Noise Contours60 dB L

DR NW

October 2017 1:50000@A4

A11131/R01/04

Aeq,16h

LEGEND:2017 Noise Contour2016 Noise Contour


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS


Comparison of 2017 and 2016Summer Daytime Noise Contours63 dB L

DR NW

October 2017 1:50000@A4

A11131/R01/05

Aeq,16h



DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS



DR NW

October 2017 1:50000@A4

A11131/R01/06

Aeq,16h



DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS



DR NW

October 2017 1:50000@A4

A11131/R01/07

Aeq,16h

A11131-R01-DR-Rev1 15 November 2017 A1.1

APPENDIX 1

GLOSSARY OF ACOUSTIC AND AVIATION TERMINOLOGY


Sound

This is a physical vibration in the air, propagating away from a source, whether heard or not.

The Decibel, dB

The unit used to describe the magnitude of sound is the decibel (dB) and the quantity

measured is the sound pressure level. The decibel scale is logarithmic and it ascribes equal

values to proportional changes in sound pressure, which is a characteristic of the ear. Use of a

logarithmic scale has the added advantage that it compresses the very wide range of sound

pressures to which the ear may typically be exposed to a more manageable range of numbers.

The threshold of hearing occurs at approximately 0 dB (which corresponds to a reference

sound pressure of 2 x 10-5 Pascals) and the threshold of pain is around 120 dB.

The sound energy radiated by a source can also be expressed in decibels. The sound power is

a measure of the total sound energy radiated by a source per second, in watts. The sound

power level, Lw is expressed in decibels, referenced to 10-12 watts.

Frequency, Hz

Frequency is analogous to musical pitch. It depends upon the rate of vibration of the air

molecules that transmit the sound and is measure as the number of cycles per second or

Hertz (Hz). The human ear is sensitive to sound in the range 20 Hz to 20,000 Hz (20 kHz). For

acoustic engineering purposes, the frequency range is normally divided up into discrete

bands. The most commonly used bands are octave bands, in which the upper limiting

frequency for any band is twice the lower limiting frequency, and one-third octave bands, in

which each octave band is divided into three. The bands are described by their centre

frequency value and the ranges which are typically used for building acoustics purposes are 63

Hz to 4 kHz (octave bands) and 100 Hz to 3150 Hz (one-third octave bands).

A-weighting

The sensitivity of the ear is frequency dependent. Sound level meters are fitted with a

weighting network which approximates to this response and allows sound levels to be

expressed as an overall single figure value, in dB(A).


Environmental Noise Descriptors

Where noise levels vary with time, it is necessary to express the results of a measurement

over a period of time in statistical terms. Some commonly used descriptors follow.

Statistical Term Description

LAeq, T The most widely applicable unit is the equivalent continuous A-

weighted sound pressure level (LAeq, T). It is an energy average

and is defined as the level of a notional sound which (over a

defined period of time, T) would deliver the same A-weighted

sound energy as the actual fluctuating sound.

LA90 The level exceeded for 90% of the time is normally used to

describe background noise.

LAmax,T The maximum A-weighted sound pressure level, normally

associated with a time weighting, F (fast), or S (slow)

Ambient Noise

Usually expressed using LAeq,T unit, commonly understood to include all sound sources present

at any particular site, regardless of whether they are actually defined as noise.

Background Noise

This is the steady noise attributable to less prominent and mostly distant sound sources above

which identifiable specific noise sources intrude.

Sound Transmission in the Open Air

Most sources of sound can be characterised as a single point in space. The sound energy

radiated is proportional to the surface area of a sphere centred on the point. The area of a

sphere is proportional to the square of the radius, so the sound energy is inversely

proportional to the square of the radius. This is the inverse square law. In decibel terms, every

time the distance from a point source is doubled, the sound pressure level is reduced by 6 dB.

Road traffic noise is a notable exception to this rule, as it approximates to a line source, which

is represented by the line of the road. The sound energy radiated is inversely proportional to

the area of a cylinder centred on the line. In decibel terms, every time the distance from a line

source is doubled, the sound pressure level is reduced by 3 dB.


Factors Affecting Sound Transmission in the Open Air

Reflection

When sound waves encounter a hard surface, such as concrete, brickwork, glass, timber or

plasterboard, it is reflected from it. As a result, the sound pressure level measured

immediately in front of a building façade is approximately 3 dB higher than it would be in the

absence of the façade.

Screening and Diffraction

If a solid screen is introduced between a source and receiver, interrupting the sound path, a

reduction in sound level is experienced. This reduction is limited, however, by diffraction of

the sound energy at the edges of the screen. Screens can provide valuable noise attenuation,

however. For example, a timber boarded fence built next to a motorway can reduce noise

levels on the land beyond, typically by around 10 dB(A). The best results are obtained when a

screen is situated close to the source or close to the receiver.

Meteorological Effects

Temperature and wind gradients affect noise transmission, especially over large distances. The

wind effects range from increasing the level by typically 2 dB downwind, to reducing it by

typically 10 dB upwind – or even more in extreme conditions. Temperature and wind gradients

are variable and difficult to predict.

Aviation Terms

Air Transport Movements

Air transport movements are landings or take-offs of aircraft engaged on the transport of

passengers, cargo or mail on commercial terms. All scheduled movements, including those

operated empty, loaded charter and air taxi movements are included.

NPR

Noise preferential route – departure flight ground tracks to be followed by aircraft to minimise

noise disturbance on the surrounding population.

Dispersion

Due to the effect of the wind, aircraft speed, and pilot choice differing aircraft tracks about the

nominal track are flown; this is known as dispersion around a nominal track.

Start of Roll

The position on a runway where aircraft commence their take-off runs.


Threshold

The beginning of that portion of the runway usable for landing.

Radar Vectoring

Aircraft are provided by Air Traffic Control with various instructions which result in changes of

heading, altitude and speed. The controller affects safe separation from other traffic by use of

radar.

Nominal Tracks

Using recognised international design techniques, tracks across the ground can be delineated

for departing and arriving aircraft. These tracks are nominal because they can be influenced by

the wind, ATC instructions, and the accuracy of navigational systems and the flight

characteristics of individual aircraft. In UK it is usual to permit a 1500m swathe to be

established about the nominal track for the purposes of assessing whether an aircraft has

stayed on track.

AAL

Height of aircraft above aerodrome level.

Altitude

Height of aircraft above sea level.

Noise Footprint

A noise contour which joins points on the ground which receive the same maximum noise

level from the nearby airborne aircraft; often for night studies 90 dB(A) SEL is the level used.

Elevation Angle

The elevation angle is the angle between the ground and the aircraft as seen from the

observer at ground level. An aircraft flying directly overhead would be at an elevation angle of

90°.


APPENDIX 2

GEORGE BEST BELFAST CITY AIRPORT

CONTOUR VALIDATION – NOISE


INTRODUCTION

Summer noise contours have been prepared for George Best Belfast City Airport (GBBCA)

based on the actual movements during the summer period for a number of years. This has

involved the use of the Federal Aviation Administration (FAA) prediction methodology, the

Integrated Noise Model (INM), which has been regularly updated. Consequently over the

years, noise contours have been produced using different versions.

The INM software has been used around the world in over 50 countries and consequently is

flexible enough to allow local circumstances to be taken into account. This can be achieved by

entering specific departure routes, operational profiles or weather conditions but also by

creating or modifying specific noise information for aircraft types.

In order to improve the accuracy of the modelling, validation exercises have been conducted

which compare predicted noise levels for individual aircraft movements with either published

noise certification levels or noise levels measured at Belfast. This is particularly useful for

aircraft types where the INM does not have actual data and so suggests a substitute type.

CURRENT VALIDATION

Validation using NMT Results

The validation exercise uses the measured results from the permanent noise monitoring

system at George Best Belfast City Airport (GBBCA). Specifically results were used from the

Noise Monitoring Terminal (NMT) at Nettlefield Primary School (MP01) and at Kinnegar Army

Camp (MP02). These NMTs are located approximately 4.5 km from the start of roll location of

runway 22 and 3.9 km from the start of roll location of runway 04. The validation exercise for

the 2017 contours uses the most recent results from the NMTs. Specifically the results for the

period September 2016 to October 2017 have been used, which comprise over 36,000

individual aircraft measurements.

The resulting average measured noise levels used for the 2017 validation exercise are given

below in Table A2.1 for the four most common aircraft types that operated in the 2017

summer period. These noise levels are compared with the corresponding measured results

used for the 2016 validation exercise. This shows that the average measured noise levels for

these types have not varied by more than 1 dB compared to 2016, with the exception of

arrivals by the Airbus A319.


Table A2.1: Measured Noise Levels used for Validation in 2017 and 2016

The 2017 exercise has considered the most common four aircraft types in the summer period

of 2017. The 2016 exercise also considered the Fokker 70 and the Let L-410, however they did

not operate in significant numbers in the 2017 summer period and so have not been validated.

The four validated aircraft comprised around 94% of the summer period movements in 2017.

They are also the types for which there are the most measured results at the noise monitors.

For each aircraft type there are four sets of measured results; arrivals and departures at each

of the two monitors. As the monitors are not located symmetrically with regard to the runway

the noise levels at each will differ and so they need to be considered separately. For the

individual movements within a set there is some variation, so every arrival by an aircraft type

does not produce exactly the same noise level. There are a number of factors which contribute

to this, in particular the weather conditions.

Aircraft Type Operation

2017 Validation Measured Noise Levels (SEL dB)


Average Number Average Number

Airbus A319

Arrival Rwy 04 84.8 212 85.8 359

Arrival Rwy 22 88.4 730 89.6 1,304

Departure Rwy 04 89.5 225 89.8 463

Departure Rwy 22 88.1 604 88.3 1,325

Airbus A320

Arrival Rwy 04 86.7 551 86.3 599

Arrival Rwy 22 89.8 1,998 89.9 1,552

Departure Rwy 04 90.6 581 90.8 681

Departure Rwy 22 88.5 1,659 88.4 1,626

Bombardier Dash 8-Q400

Arrival Rwy 04 83.1 2,737 83.1 3,069

Arrival Rwy 22 86.2 10,896 86.5 9,504

Departure Rwy 04 80.3 3,311 80.2 4,095

Departure Rwy 22 80.1 9,665 80.2 9,003

Embraer E175

Arrival Rwy 04 86.4 89 86.0 122

Arrival Rwy 22 89.2 318 89.8 424

Departure Rwy 04 89.9 94 89.7 94

Departure Rwy 22 88.1 290 87.7 463


Measured Results

The spread of results is illustrated in Figures A2.1 to A2.4 below. These show the distribution

of measured noise levels from September 2016 to October 2017 for the most common

operations, arrivals from the north and departures to the south, for the most common aircraft

types in the summer period of 2017, the Bombardier Dash 8-Q400 and the Airbus A320.

Figure A2.1 – Dash 8-Q400 Arrivals Figure A2.2 – Dash 8-Q400 Departures Figure A2.3 – Airbus A320 Arrivals Figure A2.4 – Airbus A320 Departures


The distributions have the large majority of measured noise levels closely grouped together

around the averages, shown as a vertical red line on the figures, with a pattern that

approximates to a normal distribution with a standard deviation of less than 2 dB. Such

distributions of measured noise levels are commonly found at airport fixed noise monitors at a

similar distance from the runway.

From the distributions of measured noise levels for each of the aircraft types considered, the

averages have been determined and compared to INM standard predicted noise levels.

Table A2.2 gives the latest measured average noise levels for the four aircraft types validated

in 2017.



INM Standard Assumptions

(SEL dB)

Average Number Type Level

Airbus A319

Arrival Rwy 04 84.8 212

A319-131

87.0

Arrival Rwy 22 88.4 730 90.0

Departure Rwy 04 89.5 225 87.9


Airbus A320


A320-211

87.4

Arrival Rwy 22 89.8 1,998 90.2


Departure Rwy 22 88.5 1,659 88.4


Arrival Rwy 04 83.1 2,737 SD330

82.2

Arrival Rwy 22 86.2 10,896 84.5

Departure Rwy 04 80.3 3,311 DHC6

82.1

Departure Rwy 22 80.1 9,665 81.6

Embraer E175


EMB175

85.5

Arrival Rwy 22 89.2 318 88.3



Table A2.2: Measured and Standard Predicted Noise Levels


Approach to Validation

The approach to validation modifications has been to only change from the INM standard type

when the measured results show clear divergence, i.e. an apparent prediction error in excess

of 1.5 dB at a single NMT or an average error of over 1.0 dB across both NMTs. If the type has

historically been modified from the standard type, then the approach has been to only change

from the previous validation when there is an apparent prediction error or change in

measured level in excess of 1.0 dB at a single NMT. Also the approach seeks to determine any

modification by aircraft type and aircraft operation, but not by runway used. This means one

modification is adopted for all arrivals by an aircraft type, and one for all departures by an

aircraft type.

Comparison of Measured and Predicted Results

For the Airbus A320, Bombardier Dash 8-Q400 and Embraer E175, the measured levels have

not changed sufficiently to warrant a change from the validation used for the 2016 contours.

For the Airbus A319 on departure the measured levels have also not changed sufficiently to

warrant a change from the validation used for the 2016 contours. However for arrivals

compared to 2016, the measured noise levels have decreased by 1.0 dB at MP01 and by 1.2 dB

at MP02. Consequently the predicted noise levels are higher than the measured 2017

averages by 2.2 dB at MP01 and by 1.6 dB at MP02. This leads to decreasing the modelled

number of arrival movements of this aircraft by a factor of 0.7. This is different from 2016

where a factor of 0.8 was used.

The final validation modifications are summarised below in Table A2.3. These have been used

for the 2017 contours.

Aircraft Type INM Type Modification to Movements Numbers

Departures Arrivals

Airbus A319 A319-131 A319-131 × 1.4 A319-131 × 0.7

Airbus A320 A320-211 A320-211 × 1.1 A320-211

Bombardier Dash 8-Q400 DHC6/SD330 DHC6 × 0.8 SD330 × 1.4

Embraer E175 737500/EMB175 737500 × 1.3 EMB175 x 1.2

Table A2.3: 2017 Validation Modifications

Table A2.3 shows that for the two Airbus types, modifications to the number of movements

have been made. For the Airbus A319 arrival movements have been factored down with the

departure movements factored up. For the Airbus A320, no modification was necessary for

arrival movements, and departure movements have been factored up slightly.


The need for modifications for the larger aircraft types in particular is not unexpected as they

are available in a range of specifications with different engine types, sometimes from different

manufacturers. This means that the actual type operated by the airline may differ to the one

in the INM software and this is the case here for both the Airbus A319 and A320.

For the Embraer E175, modifications were needed to the INM type as the standard type does

not agree well with the measured departure results. On arrival the standard type was used,

but with movements factored up.

For the Dash 8-Q400 the INM software does not suggest a type. The validation finds that using

the Dash 6 (DHC6) for departures and the Shorts 330 (SD330) for arrivals, with movement

numbers factored, agrees well with measured noise levels.

Effect of Validation

The effect of the validation exercise on the predicted noise levels for the four aircraft types is

detailed in Table A2.4 which gives the differences between the measured noise levels and

those predicted after allowing for the validation modifications.



Noise Levels (SEL dB)

Measured Average

INM Validated Prediction

Difference Predicted - Measured

Operation Weighted Average

Difference

Airbus A319

Arrival Rwy 04 84.8 85.5 +0.7 +0.2

Arrival Rwy 22 88.4 88.5 +0.1

Departure Rwy 04 89.5 89.4 -0.1 +0.3

Departure Rwy 22 88.1 88.5 +0.4

Airbus A320

Arrival Rwy 04 86.7 87.4 +0.7 +0.4

Arrival Rwy 22 89.8 90.2 +0.4

Departure Rwy 04 90.6 88.9 -0.7 +0.1

Departure Rwy 22 88.5 89.9 +0.4


Arrival Rwy 04 83.1 83.7 +0.6 -0.1

Arrival Rwy 22 86.2 86.0 -0.2

Departure Rwy 04 80.3 81.1 +0.8 +0.6

Departure Rwy 22 80.1 80.6 +0.5

Embraer E175

Arrival Rwy 04 86.4 86.3 -0.1 -0.1

Arrival Rwy 22 89.2 89.1 -0.1

Departure Rwy 04 89.9 88.9 -1.0 +0.1

Departure Rwy 22 88.1 88.5 +0.4

Table A2.4: Measured and Validated Predicted Noise Levels

Table A2.4 shows that with the validation modifications there is good correlation between

measured and predicted noise levels with differences generally less than 0.5 dB when results

from both NMTs are operationally averaged, with the exception of departures by the Dash 8-

Q400 where the difference is 0.6 dB.

The effect of the validation exercises on the contours depends both on the modifications

made and the contribution of those aircraft types to the overall noise. Obviously changes to

infrequent aircraft types are likely to have very little effect on the contours.


SUMMARY

The validation of noise contours at George Best Belfast City Airport has been continually

improved, more recently by checking predictions against the results obtained from GBBCA’s

noise monitors. This has demonstrated that without validation the standard INM assumptions

would be less accurate.

The latest contours have taken into account over 36,000 individual aircraft noise

measurements at GBBCA between September 2016 and October 2017. This has identified the

need to modify the standard INM assumptions for four aircraft, the Airbus A319, Airbus A320,

Bombardier Dash 8-Q400 and Embraer E175.

GBBCA will continue to collect further detailed information from the fixed noise monitors at

Nettlefield Primary School and in Kinnegar, which will be used to regularly validate future

GBBCA contours. That is in line with the EiP Panel’s advice on contour validation.


APPENDIX 3

INM SUBSTITUTION LIST


Table A3.1 gives a full list of the aircraft operational codes, as used by the airport, and the corresponding INM aircraft codes that were used to model the aircraft.

Aircraft operational code

Substituted INM aircraft code

Aircraft operational code

Substituted INM aircraft code

141 BAE146 DH8 DHC6/SD330(1)

142 BAE146 E75 EMB175/737500(1)

319 A319-131(1) E90 EMB190

320 A320-211(1) E95 EMB195

321 A321-232 ER3 EMB145

73Y 737300 ERJ EMB145

AR8 BAE146 GRJ GV

BET CNA441 H25 LEAR35

CCJ CL600 J32 DO228

CCX GV J41 SF340

CN1 CNA172 JET CNA500

CN7 CNA750 L2J CNA500

CNJ CNA500 MP1 GASEPF

DF2 FAL20 MP2 BEC58P

DF3 F10062 PA2 PA28

DF7 F10062 PAG PA42

DH4 DHC6/SD330(1) PL2 CNA208

[1] Aircraft type modified based on validation exercise

Table A3.1: INM Substitution List

Documents

AIRBORNE AIRCRAFT NOISE CONTOURS 2017 · 2.2 Traffic Distribution by Aircraft Type The basis for the 2017 noise contours are the actual movements during the 92 day summer period,