AIRBORNE AIRCRAFT NOISE CONTOURS 2016 · Architects: Design and project management services which cover all stages of design, from feasibility and ... (GBBCA) to produce airborne

Report to George Best Belfast City Airport Sydenham By-Pass Belfast BT3 9JH A11019-R01B-DR 10 January 2017

GEORGE BEST BELFAST CITY AIRPORT

AIRBORNE AIRCRAFT NOISE

CONTOURS 2016

A11019-R01B-DR 10 January 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.

A11019-R01B-DR 10 January 2017 3

Contents Page No.

1.0 Introduction .................................................................................................................................. 5

2.0 Aircraft Operations ...................................................................................................................... 5

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

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

5.0 Summary ..................................................................................................................................... 14

Figures

Figure A11019/R01/01: Initial Departure Routes

Figure A11019/R01/02: Daytime Summer Noise Contours 2016 – 54 to 69 dB LAeq,16h in 3 dB steps

Figure A11019/R01/03: Comparison of 2016 and DoE Indicative Daytime Noise Contours – 63 dB LAeq,16h

Figure A11019/R01/04: Comparison of 2016 and DoE Indicative Daytime Noise Contours – 60 dB LAeq,16h

Figure A11019/R01/05: Comparison of 2016 and 2015 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

A11019-R01B-DR 10 January 2017 4

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.

A11019-R01B-DR 10 January 2017 5

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 2016.

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 2015 were

reported in BAP’s report Ref: A9920-R01-DR, dated December 2015.

This report sets out the assumptions used in the computation of the 2016 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 2016 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

A11019-R01B-DR 10 January 2017 6

information was provided for all aircraft movements during the 92 day period in 2016.

Although a small proportion of movements, occur early in the morning between 0630 hours

and 0700 hours 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 0700 hours to

2300 hours.

The actual movements in 2016 also include 30 movements by helicopters. Historically,

helicopters have not been modelled at GBBCA as they typically comprise around 1% or less of

the total movements, and this was also the case in 2016, 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 2016 by INM type, as well as the

movements for summer 2015 for comparison purposes.

A11019-R01B-DR 10 January 2017 7

Aircraft Type INM Designator 2016

Movements 2015

Movements

Airbus A319 A319-131(1) 634 5.4% 1,450 13.0%

Airbus A320 A320-211(1) 1,662 14.2% 1,213 10.9%

Avions de Transport Regional ATR-72 DO328 66 0.6% n/a(2) n/a(2)

Beechcraft - twin turboprop CNA441 19 0.2% 33 0.3%

Boeing 717-200 717200 n/a(2) n/a(2) 26 0.2%

British Aerospace BAe 125-800 LEAR35 n/a(2) n/a(2) 22 0.2%

British Aerospace BAe 146-200 BAE146 n/a(2) n/a(2) 12 0.1%

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

Cessna Citation Jet CNA500 54 0.5% 46 0.4%

De Havilland Dash 8-400 DHC6/SD330(1) 8,054 68.8% 7,074 63.3%

Embraer EMB-170-200 EMB175/737500(1) 194 1.7% 393 3.5%

Embraer EMB-190-100 EMB190 n/a(2) n/a(2) 12 0.1%

Fokker 70 F10062/737800(1) 184 1.6% 173 1.5%

Gulfstream Jet GV n/a(2) n/a(2) 28 0.3%

Let L-410 DHC6/SD330(1) 534 4.6% 537 4.8%

Miscellaneous business jet CNA500 53 0.5% 40 0.4%

Miscellaneous prop, single engine GASEPF 28 0.2% n/a(2) n/a(2)

Miscellaneous prop, twin engine BEC58P 13 0.1% n/a(2) n/a(2)

Pilatus PC-12 CNA208 14 0.1% 39 0.3%

Saab 2000 HS748A n/a(2) n/a(2) 12 0.1%

Other (less than 10 movements) 74 0.6% 65 0.6%

Total 11,710 100% 11,175 100%

(1) Aircraft Type modified based on results of 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 2016 and 2015 Summer Contours

A11019-R01B-DR 10 January 2017 8

In summary, the overall movement numbers have increased by around 5% from 2015 to 2016.

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

Bombardier Dash 8-Q400, Let L-410) and twin engined turbofan aircraft (e.g. Airbus A320

family). The majority of the increase in overall movements is due to the increase in

Dash 8-Q400 movements in 2016, leading to an overall increase in the proportion of

turboprop movements. Airbus A320 movements have also increased, but the decrease in

other turbofan movements, by the Airbus A319 and Embraer E175, more than outweighs this,

meaning that movements by large turbofan aircraft have decreased overall.

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 A11019/R01/01 and have been used for the 2016 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 2016 summer period is given in Table 2,

and is compared with that for 2015. For the modelling, the actual runway usage for each

individual movement was used.

Runway 2016 Movements 2015 Movements

Arrivals Departures Arrivals Departures

04 1086

(18.5%)

1335

(22.8%)

1,520

(27.2%)

1,832

(32.8%)

22 4770

(81.5%)

4519

(77.2%)

4,070

(72.8%)

3,753

(67.2%)

Table 2: Summer 2016 and 2015 Runway Usage

For both arrivals and departures there has been an increase of around 10% in activity on

runway 22 with a corresponding decrease in activity on runway 04.

A11019-R01B-DR 10 January 2017 9

For each runway there is a single arrival route. There is one initial departure route on

runway 22 but four assumed departure routes on runway 04, as shown in Figure

A11019/R01/01. 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 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. Stage length 1 is assumed for all aircraft operating

from GBBCA as this is the case for the large majority of departures.

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 2016 database.

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

using flight track information, aircraft fleet mix, standard defined aircraft profiles, 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.

A11019-R01B-DR 10 January 2017 10

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 2016 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 2015 to September 2016 have been used for the 2016 validation exercise to review

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

The 2016 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.

A11019-R01B-DR 10 January 2017 11

Aircraft Type Default INM

Type

Modification to Movements Numbers

Departures Arrivals

Airbus A319 A319-131 A319-131 × 1.4 A319-131 × 0.8

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

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

Embraer E175 EMB175 737500 × 1.3 EMB175 × 1.2

Fokker 70 F10062 737800 × 0.6 F10062 × 1.4

Let L-410 DHC6 DHC6 × 2.0 SD330

Table 3: Modifications to INM Assumptions used for 2016 Contours

These modifications to INM assumptions are similar to those used for the 2015 contours; they

have been modified for the Embraer E175 and the Fokker 70 on departure. For both aircraft

the departure multiplier has been reduced by 0.2 compared to the multiplier used in 2015. Full

details of the 2016 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 hours to 23:00 hours; although they also include the small number of

movements that occurred between 06:30 and 07:00. They are based on the actual movements

for the summer 92 day period in 2016. Daytime 16 hour contours of this type, shown in Figure

A11019/R01/02, 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 2015.

Figure A11019/R01/03 shows a comparison between the 63 dB LAeq,16h daytime contour based

on the 2016 movements and the DoE indicative contour resolved in 1997. The 2016 contour is

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

residential properties within the 2016 contour.

Figure A11019/R01/04 shows a comparison between the 60 dB LAeq,16h daytime contour based

on the 2016 movements and the DoE indicative contour. The 2016 contour is again shorter

than the indicative contour and slightly wider in some locations. There are again no residential

properties within the 2016 contour in the locations where it is wider than the indicative

contour, and the 2016 contour does not extend as far into Ballymacarrett or contain as many

properties in the Kinnegar area of Holywood as compared to the indicative contour. Figures

A11019/R01/05 to A11019/R01/07 show comparisons between 2016 and 2015 for the 63, 60

and 57 dB LAeq,16h contours respectively.

A11019-R01B-DR 10 January 2017 12

Table 4 shows the area of the 2016 and 2015 LAeq,16h contours.

Contour Level

(dB LAeq,16h)

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

2016 vs. 2015 2016 2015

54 7.17 7.32 -2%

57 3.66 3.77 -3%

60 1.80 1.86 -3%

63 0.96 0.99 -3%

66 0.56 0.58 -3%

69 0.34 0.36 -6%

Table 4: Comparison of 2016 and 2015 Noise Contour Areas

Table 4 shows that the 2016 contour areas are slightly smaller than those for the 2015

contours, by between 2-3%, with the exception of the 69 dB contour which is 6% smaller

compared to 2015. Figures A11019/R01/05 to A11019/R01/07 show that the contours are

very similarly located with those for 2016 extending slightly further north, but not as far to the

south than the 2015 contours. This slight change in shape is attributed to the different runway

splits in 2016, with a greater proportion of flights on runway 22.

The decrease in contour area from 2015 to 2016 is despite a 5% increase in total aircraft

movements. The decrease is due to the increased proportion of quieter turbo-prop aircraft,

while movements by the louder passenger jets have actually decreased in number. The change

in validation for 2016 also causes a small reduction in contour area, due to quieter measured

departure noise levels from the Embraer E175s and Fokker 70s.

A11019-R01B-DR 10 January 2017 13

4.1 Population Counts

Population counts for the 2016 and 2015 LAeq,16h daytime contours are given in Table 5 and

Table 6 below.

Contour Level (dB LAeq,16h) 2016 Population 2015 Population

54 15,530 16,150

57 4,977 5,622

60 32 31

63 0 0

66 0 0

69 0 0

Table 5: Comparison of 2016 and 2015 Population Counts – Cumulative Totals

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

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

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

2015 0 0 0 31 5,591 10,528 16,150

Table 6: Comparison between 2016 and 2015 Population Counts

Table 5 and Table 6 show that there are no people exposed to 63 dB LAeq,16h or higher in 2016,

as was the case in 2015. The population exposed to between 60 and 63 dB LAeq,16h has

increased by 1, this is due to an update to the population database used as opposed to an

actual change in affected population. The population within the 57 to 60 dB LAeq,16h band has

decreased by 646. 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 increased slightly, this is due to the slightly different shape of the 2016 contour as a

result of the change in runway split compared to 2015.

A11019-R01B-DR 10 January 2017 14

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 2016.

The 2016 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 areas where the 2016

contours are larger than the indicative contours.

The 2016 LAeq,16h contours are similar in shape, but smaller by an average of 3%, compared to

the 2015 LAeq,16h contours. This is primarily attributed to the decrease in the number of

movements by commercial turbofan aircraft, which outweighs in noise terms, the increase in

overall movements.

The total population within the 2016 contours is smaller than that within the 2015 contours,

due to the contours being smaller in size, although some contour bands show small increases

in population due to the updated population database and the slightly different contour shape

due to the change in runway splits.

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 2016.

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 DC

15/12/2016 1:125000@A4

A11019/R01/01

54

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


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS


2016 Summer Daytime Noise Contours

DR DC

15/12/2016 1:50000@A4

A11019/R01/02

LEGEND:2016 Noise ContourDoE Indicative Noise Contour


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS


Comparison of 2016 and DoE Indicative Summer Daytime Noise Contours63 dB L

DR DC

15/12/2016 1:50000@A4

A11019/R01/03

Aeq,16h

LEGEND:2016 Noise ContourDoE Indicative Noise Contour


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS


Comparison of 2016 and DoE Indicative Summer Daytime Noise Contours60 dB L

DR DC

15/12/2016 1:50000@A4

A11019/R01/04

Aeq,16h

LEGEND:2016 Noise Contour2015 Noise Contour


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS


Comparison of 2016 and 2015Summer Daytime Noise Contours63 dB L

DR DC

15/12/2016 1:50000@A4

A11019/R01/05

Aeq,16h



DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS



DR DC

15/12/2016 1:50000@A4

A11019/R01/06

Aeq,16h



DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS



DR DC

15/12/2016 1:50000@A4

A11019/R01/07

Aeq,16h

A11019-R01B-DR 10 January 2017 A1.1

APPENDIX 1

GLOSSARY OF ACOUSTIC & AVIATION TERMINOLOGY

A11019-R01B-DR 10 January 2017 A1.2

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).

A11019-R01B-DR 10 January 2017 A1.3

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.

A11019-R01B-DR 10 January 2017 A1.4

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.

A11019-R01B-DR 10 January 2017 A1.5

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, 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.

Night Period

The period from 23.00 to 07.00 hours.

Night Quota Period

The period from 23.30 to 06.00 hours.

Noise Classification (QC Value)

This means the noise level band in EPNdB, for take-off or landing, as the case may be, for the

aircraft. The bands are identified as QC/0.5, QC/1, QC/2, QC/4. QC/8, QC/16, and are 3 dB

wide.

Quota Count

This means the amount of the quota assigned to one take-off or to one landing by an aircraft,

this number being related to its noise classification.

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.

A11019-R01B-DR 10 January 2017 A2.1

APPENDIX 2

GEORGE BEST BELFAST CITY AIRPORT

CONTOUR VALIDATION – NOISE

A11019-R01B-DR 10 January 2017 A2.2

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 is regularly updated. Consequently over the years, noise

contours have been produced using different versions.

The INM software is 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 2016 contours uses the most recent results from the NMTs. Specifically the results for the

period September 2015 to September 2016 have been used, which comprise over 37,000

individual aircraft measurements.

The resulting average measured noise levels used for the validation exercise in 2016 are given

below in Table A2.1 for the three most common aircraft types that operated in the 2016

summer period, these noise levels are compared with the corresponding measured results

used for the 2015 validation exercise. This shows that in the average measured noise levels for

these types have not varied by more than 1 dB compared to 2015.

A11019-R01B-DR 10 January 2017 A2.3

Table A2.1: Measured Noise Levels used for Validation in 2016 and 2015

The 2016 exercise has considered the most common 6 aircraft types in the summer period of

2016, which in addition to those mentioned in the table above are the Embraer E175, the Let

L-410 and the Fokker 70. These aircraft comprised around 96% of the summer period

movements in 2016. 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

2016 Validation Measured Noise Levels (SEL dB)


Average Number Average Number

Airbus A319

Arrival Rwy 04 85.8 359 85.7 204

Arrival Rwy 22 89.6 1,304 90.0 1,810

Departure Rwy 04 89.8 463 90.1 653

Departure Rwy 22 88.3 1,325 87.7 904

Airbus A320

Arrival Rwy 04 86.3 599 86.1 232

Arrival Rwy 22 89.9 1,552 90.1 1,857

Departure Rwy 04 90.8 681 91.1 634

Departure Rwy 22 88.4 1,626 87.7 1,155

Bombardier Dash 8-Q400

Arrival Rwy 04 83.1 3,069 82.8 1,098

Arrival Rwy 22 86.5 9,504 86.9 10,235

Departure Rwy 04 80.2 4,095 81.1 4,037

Departure Rwy 22 80.2 9,003 80.4 5,363

A11019-R01B-DR 10 January 2017 A2.4

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 2015 to September 2016 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 2016, the Bombardier Dash 8-Q400 and the Airbus A320.

Figure A2.1 – Dash 8-Q400 Departures Figure A2.2 – Dash 8-Q400 Arrivals

Figure A2.3 – Airbus A319 Departures Figure A2.4 – Airbus A319 Arrivals

A11019-R01B-DR 10 January 2017 A2.5

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

around the averages, shown as a vertical orange 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 three most common aircraft

types in the 2016 summer period which comprised around 88% of movements.



INM Standard Assumptions

(SEL dB)

Average Number Type Level

Airbus A319

Arrival Rwy 04 85.8 359

A319-131

87.0

Arrival Rwy 22 89.6 1,304 90.0

Departure Rwy 04 89.8 463 87.9

Departure Rwy 22 88.3 1,325 87.0

Airbus A320

Arrival Rwy 04 86.3 599

A320-211

87.4

Arrival Rwy 22 89.9 1,552 90.2

Departure Rwy 04 90.8 681 89.4

Departure Rwy 22 88.4 1,626 88.2


Arrival Rwy 04 83.1 3,069 SD330

82.2

Arrival Rwy 22 86.5 9,504 84.5

Departure Rwy 04 80.2 4,095 DHC6

82.1

Departure Rwy 22 80.2 9,003 81.6

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 in excess of 1.0 dB at

A11019-R01B-DR 10 January 2017 A2.6

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 A319, Airbus A320, Bombardier Dash 8-Q400 and Let L-410, the measured

levels have not changed sufficiently to warrant a change from the validation used for the 2015

contours.

For the Embraer E175 on arrival the measured levels have also not changed sufficiently to

warrant a change from the validation used for the 2015 contours. However for departures

compared to 2015, the measured noise levels have decreased by 0.4 dB at MP01 and by 0.9 dB

at MP02. Consequently the predicted noise levels are lower than the measured 2016 averages

by 0.3 dB at MP01 and by 1.9 dB at MP02. This leads to increasing the modelled number of

departure movements of this aircraft by a factor of 1.3. This is different from 2015 where a

factor of 1.5 was used.

The Fokker 70 was first validated in 2015, as it had not operated in significant numbers at

GBBCA before. INM does not include this type however it suggests the F10062 as a suitable

substitution. On arrival the predicted noise levels are lower than the measured averages by

1.0 dB at MP01 and by 2.0 dB at MP02, and so a modification has been made. This is to

increase the modelled number of arrivals of this aircraft by a factor of 1.4, as was used for the

2015 validation exercise. For departures the predicted noise levels for the F10062 are

significantly lower than the measured noise levels. As a result various different aircraft were

considered to model the Fokker 70 departures. The best result was achieved by using the

Boeing 737800 multiplied by a factor, as was the case for 2015. Compared to 2015 the

measured noise levels have decreased by 0.8 dB at MP01 and by 1.0 dB at MP02.

Consequently the factor applied has decreased from 0.8 in 2015 to 0.6 in 2016.

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

for the 2016 contours.

A11019-R01B-DR 10 January 2017 A2.7

Aircraft Type INM Type Modification to Movements Numbers

Departures Arrivals

Airbus A319 A319 A319-131 × 1.4 A319-131 × 0.8

Airbus A320 A320 A320-211 × 1.1 A320-211

Bombardier Dash 8-Q400 DH8D DHC6 × 0.8 SD330 × 1.4

Embraer E175 E175 737500 × 1.3 EMB175 x 1.2

Fokker 70 F70 737800 × 0.6 F10062 × 1.4

Let L-410 L410 DHC6 × 2.0 SD330

Table A2.3: 2016 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 and the Let L-410 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 (differently for the two actual aircraft types),

agrees well with measured noise levels.

For the Fokker 70 the INM software suggests the Fokker 100 (F10062). On arrival this under

predicted the noise level therefore the movement numbers were factored up. On departure

the predicted noise levels varied significantly from the measured results, therefore a different

aircraft type was used and the movement numbers were factored down.

Effect of Validation

The effect of the validation exercise on the predicted noise levels for the three most common

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.

A11019-R01B-DR 10 January 2017 A2.8


Noise Levels (SEL dB)

Measured Average

INM Validated Prediction

Difference Predicted / Measured

Operation Weighted Average

Difference

Airbus A319

Arrival Rwy 04 85.8 86.0 +0.2 -0.4

Arrival Rwy 22 89.6 89.0 -0.6

Departure Rwy 04 89.8 89.4 -0.4 +0.0

Departure Rwy 22 88.3 88.5 +0.2

Airbus A320

Arrival Rwy 04 86.3 87.4 +1.1 +0.5

Arrival Rwy 22 89.9 90.2 +0.3

Departure Rwy 04 90.8 89.8 -1.0 -0.2

Departure Rwy 22 88.4 88.6 +0.2


Arrival Rwy 04 83.1 83.7 +0.6 -0.2

Arrival Rwy 22 86.5 86.0 -0.5

Departure Rwy 04 80.2 81.1 +0.9 +0.6

Departure Rwy 22 80.2 80.6 +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 arrivals 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.

The validation for the most common aircraft types operating in 2016 is unchanged compared

to 2015.

A11019-R01B-DR 10 January 2017 A2.9

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 37,000 individual aircraft noise

measurements at GBBCA between September 2015 and September 2016. This has identified

the need to modify the standard INM assumptions for several aircraft including the most

common aircraft types, the Airbus A319, Airbus A320 and Bombardier Dash 8-Q400.

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.

A11019-R01B-DR 10 January 2017 A3.1

APPENDIX 3

INM SUBSTITUTION LIST

A11019-R01B-DR 10 January 2017 A3.2

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 DH4 DHC6/SD330(1)

142 BAE146 E75 EMB175/737500(1)

319 A319-131(1) ER3 EMB145

320 A320-211(1) ER4 EMB145

321 A321-232 ERJ EMB145

AR1 BAE300 F50 CVR580

AT7 DO328 F70 F10062/737800(1)

ATR DO328 GRJ GV

BEC CNA441 H25 LEAR35

BET CNA441 JET CNA500

CCJ CL600 L2J CNA500

CCX GV L4T DHC6/SD330(1)

CN1 CNA172 LRJ LEAR35

CN2 BEC58P MP1 GASEPF

CN7 CNA750 MP2 BEC58P

CNJ CNA500 PA2 PA28

CR2 CL601 PL2 CNA208

DF7 F10062 S20 HS748A

Table A3.1: INM Substitution List

AIRBORNE AIRCRAFT NOISE CONTOURS 2016 · Architects: Design and project management services which cover all stages of design, from feasibility and ... (GBBCA) to produce airborne

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