GEORGE BEST BELFAST CITY AIRPORT AIRBORNE AIRCRAFT … · 2.2 Traffic Distribution by Aircraft Type The basis for the 2015 noise contours are the actual movements during the 92 day

Report to George Best Belfast City Airport Sydenham By‐Pass Belfast BT3 9JH A9920‐R01B‐DR 14 December 2015

GEORGE BEST BELFAST CITY AIRPORT

AIRBORNE AIRCRAFT NOISE

CONTOURS 2015

A9920‐R01B‐DR 14 December 2015 2

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Contents Page No.

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

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

3.0 INM Model ................................................................................................................................... 10

4.0 Noise Contours ............................................................................................................................ 12

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

Figures

Figure A9920/R01/01: Initial Departure Routes

Figure A9920/R01/02: Daytime Summer Noise Contours 2015 – 54 to 69 dB LAeq,16h in 3 dB steps

Figure A9920/R01/03: Comparison of 2015 and DoE Indicative Daytime Noise Contours – 63 dB LAeq,16h

Figure A9920/R01/04: Comparison of 2015 and DoE Indicative Daytime Noise Contours – 60 dB LAeq,16h

Figure A9920/R01/05: Comparison of 2015 and 2014 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


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.


1.0 INTRODUCTION

Bickerdike Allen Partners (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 2015.

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 using results

from the Noise Monitoring Terminals (NMTs) installed at GBBCA for the most common aircraft

types operating there.

Noise contours have been produced annually at GBBCA for several years. Those for 2014 were

reported in BAP’s report Ref: A9808‐R01‐EV, dated November 2014.

This report sets out the assumptions used in the computation of the 2015 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 type 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 2015 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 2015.

Although there are a number of early morning movements between 0630 hours and 0700

hours over the 92 day period, for the purposes of this study all movements are assumed to

take place within the “daytime period” of 0700 hours to 2300 hours.

The actual movements in 2015 also include 23 movements by helicopters. Historically,

helicopters have not been modelled at GBBCA as given their noise output and considering they

typically comprise around 1% or less of the total movements with a prevalence of larger jet

aircraft, their omission is not considered significant. In 2015 helicopters still comprised less

than 1% of the total movements, and so 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 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.

Table 1 shows the 2015 aircraft split over the 92 day summer period and how these have been

modelled in INM. For comparison purposes, the INM aircraft types and associated movement

numbers used to generate the 2014 contours are also given in Table 1.


Aircraft Type INM Designator 2015

Movements 2014

Movements

Airbus A319 A319‐131(1) 1,450 13.0% 1,616 16.2%

Airbus A320 A320‐211(1) 1,213 10.9% 932 9.3%

Airbus A321 A321‐232 n/a(2) n/a(2) 10 0.1%

Beechcraft ‐ twin turboprop CNA441 33 0.3% 19 0.2%

Boeing 717‐200 717200 26 0.2% 24 0.2%

British Aerospace BAe 125‐800 LEAR35 22 0.2% 34 0.3%

British Aerospace BAe 146‐200 BAE146 12 0.1% 24 0.2%

British Aerospace Bae Jetstream 31 DO228 n/a(2) n/a(2) 251 2.5%

Cessna Citation II CNA500 n/a(2) n/a(2) 10 0.1%

Cessna Citation Jet CNA500 46 0.4% 79 0.8%

De Havilland Dash 8‐400 DHC6/SD330(1) 7,074 63.3% 5,738 57.4%

Embraer EMB‐170‐200 EMB175/737500(1) 393 3.5% 563 5.6%

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

Embraer EMB‐190‐200 EMB195 n/a(2) n/a(2) 30 0.3%

Fokker 70 F10062/737800(1) 173 1.5% n/a(2) n/a(2)

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

Let L‐410 DHC6/SD330(1) 537 4.8% 526 5.3%

Miscellaneous business jet CNA500 40 0.4% 19 0.2%

Miscellaneous prop, single engine GASEPF n/a(2) n/a(2) 10 0.1%

Miscellaneous prop, twin engine BEC58P n/a(2) n/a(2) 11 0.1%

Pilatus PC‐12 CNA208 39 0.3% 41 0.4%

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

Other (less than 10 movements) 65 0.6% 58 0.6%

Total 11,175 100% 9,995 100%

Table 1: Aircraft Types used in INM for 2015 and 2014 Summer Contours

(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.


In summary, the overall movement numbers have increased by around 12% from 2014 to

2015. 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 2015, leading to an overall increase in the proportion of turboprop

movements. Airbus A320 movements have also increased slightly, matching a similar decrease

in A319 movements, and there has been a reduction in movements by the Embraer E‐Jets. The

Bae Jetstream 31 has ceased to operate at GBBCA in 2015, while the Fokker 70 has begun

operating.

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 A9920/R01/01 and have been used for the 2015 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 2015 summer period is given in Table 2,

along with that for 2014. For the modelling, the actual runway usage by aircraft type was used.

Runway 2015 Movements 2014 Movements

Arrivals Departures Arrivals Departures

04 1,520

(27.2%)

1,832

(32.8%)

2,050

(41.0%)

2,516

(34.7%)

22 4,070

(72.8%)

3,753

(67.2%)

2,949

(59.0%)

2,480

(65.3%)

Table 2: Summer 2015 and 2014 Runway Usage

The runway usage for departures remains similar with a slight increase of 2% in operations on

runway 22. Arrival operations on runway 22 have increased significantly with an increase of

around 13%.

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

A9920/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 when the aircraft type involved is expected to have

achieved one of a set of specific heights. These are 1,500 ft for small propeller aircraft (up to

5700 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 and then 1000 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.

A9920‐R01B‐DR 14 December 2015 10

3.0 INM MODEL

3.1 General

All contours and population counts are 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 2015 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.

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 2015 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

A9920‐R01B‐DR 14 December 2015 11

September 2014 to October 2015 have been used for the 2015 validation exercise to review

the INM assumptions for the common aircraft types.

The 2015 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.

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/SD330 DHC6 × 0.8 SD330 × 1.4

Embraer 175 EMB175 737500 × 1.5 EMB175 × 1.2

Fokker 70 F10062 737800 × 0.8 F10062 × 1.4

Let L‐410 DHC6 DHC6 × 2.0 SD330

Table 3: Modifications to INM Assumptions used for 2015 Contours

These modifications to INM assumptions are similar to those used for the 2014 contours; they

have been modified for the Airbus A320 on departure and the Embraer E170 on arrival. The

Fokker 70 didn’t operate at GBBCA in 2014 so has not been validated previously. The 2015

validation exercise is detailed in Appendix 2.

A9920‐R01B‐DR 14 December 2015 12

4.0 NOISE CONTOURS

4.1 Daytime LAeq,16h 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 technically 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 2015. Daytime 16 hour contours of this type, shown in Figure

A9920/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 contour areas for 2014.

Figure A9920/R01/03 shows a comparison between the 63 dB LAeq,16h daytime contour based

on the 2015 movements and the DoE indicative contour resolved in 1997. The 2015 contour is

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

residential properties within the 2015 contour.

Figure A9920/R01/04 shows a comparison between the 60 dB LAeq,16h daytime contour based

on the 2015 movements and the DoE indicative contour. The 2015 contour is again shorter

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

properties within the 2015 contour in the locations where it is wider than the indicative

contour, and the 2015 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 A9920/R01/05 to A9920/R01/07 show comparisons between 2015 and 2014 for the

63, 60 and 57 dB LAeq,16h contours respectively.

A9920‐R01B‐DR 14 December 2015 13

Table 4 shows the difference in area between the 2015 and 2014 LAeq,16h contours.

Contour Level

(dB LAeq,16h)

Area of Daytime Air Noise Contours (km2) Increase in Contour Area 2015 vs. 2014 2015 2014

54 7.32 6.99 5%

57 3.77 3.58 5%

60 1.86 1.77 5%

63 0.99 0.95 4%

66 0.58 0.56 4%

69 0.36 0.36 0%

Table 4: Comparison between 2015 and 2014 Noise Contour Areas

Table 4 shows that the 2015 contour areas are consistently larger than those for the 2014

contours, on average by 5%. Figures A9920/R01/05 to A9920/R01/07 show that the 2015 and

2014 contours are similar in shape.

The increase in contour area from 2014 to 2015 is due to the 12% increase in aircraft

movements, from 9,995 in 2014 to 11,175 in 2015. The increase is of a smaller magnitude than

might be expected for a 12% increase in aircraft movements, as there has been an increase in

the proportion of quieter turbo‐prop aircraft.

4.2 Population Counts

Population counts for the 2015 and 2014 LAeq,16h daytime contours are given in Table 5 and

Table 6.

Contour Level (dB LAeq,16h) 2015 Population 2014 Population

54 16,150 14,126

57 5,622 4,106

60 31 41

63 0 0

66 0 0

69 0 0

Table 5: Comparison between 2015 and 2014 Population Counts – Cumulative Totals

A9920‐R01B‐DR 14 December 2015 14

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

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

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

2014 0 0 0 41 4,065 10,020 14,126

Table 6: Comparison between 2015 and 2014 Population Counts

Table 5 and Table 6 show that there is an increase in the population within the contours from

2014 to 2015. There are no people exposed to 63 dB LAeq,16h or higher in 2015, as was the case

in 2014. The population exposed to between 60 and 63 dB LAeq,16h has decreased from 41 in

2014 to 31 in 2015, 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

increased by 1,526. Proportionally, this is greater than the associated increase in contour area

as the local population is not evenly distributed over the contour area so 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.

For the 54 to 57 dB LAeq,16h contour band the relative increase in population is lower, around

5%.

5.0 SUMMARY

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

movements during the 92‐day summer period in 2015.

The 2015 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 2015

contours are larger than the indicative contours.

The 2015 LAeq,16h contours are similar in shape, but larger by an average of 5%, than the 2014

LAeq,16h contours. This is attributed to the increase in aircraft movements.

The assessed population within the 2015 contours is larger than that within the 2014

contours, due to the contours being larger in size.

Duncan Rogers David Charles Peter Henson

for Bickerdike Allen Partners Associate Partner

LEGEND:

This drawing contains Ordnance Survey data © CrownCopyright and database right 2015.

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 Citty AirportNoise Contours

Initial Departure Routes

DR DC

10/11/2015 1:125000@A4

A9920/R01/01

Initial Departure Routes

54

LEGEND:


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS


2015 Summer Daytime Noise Contours

DR DC

10/11/2015 1:50000@A4

A9920/R01/02

Noise Contours,

54 to 69 dB LAeq,16h in 3 dB steps

LEGEND:


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS


Comparison of 2015 and DoE IndicativeSummer Daytime Noise Contours63 dB L

DR DC

10/11/2015 1:50000@A4

A9920/R01/03

2015 Contour

DoE Indicative Noise Contour

Aeq,16h

LEGEND:


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS


Comparison of 2015 and DoE IndicativeSummer Daytime Noise Contours60 dB L

DR DC

10/11/2015 1:50000@A4

A9920/R01/04

2015 Contour

DoE Indicative Noise Contour

Aeq,16h

LEGEND:


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS


Comparison of 2015 and 2014Summer Daytime Noise Contours63 dB L

DR DC

10/11/2015 1:50000@A4

A9920/R01/05

2015 Noise Contour

2014 Noise Contour

Aeq,16h

LEGEND:


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS



DR DC

10/11/2015 1:50000@A4

A9920/R01/06

2015 Noise Contour

2014 Noise Contour

Aeq,16h

LEGEND:


DRAWN: CHECKED:

DATE: SCALE:

FIGURE No:


REVISIONS



DR DC

10/11/2015 1:50000@A4

A9920/R01/07

2015 Noise Contour

2014 Noise Contour

Aeq,16h

A9920‐R01B‐DR 14 December 2015 A1.1

APPENDIX 1

GLOSSARY OF ACOUSTIC & 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, 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.


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 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

modifying or creating specific noise information for aircraft types.

As a way of checking on 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 or where no mention is made of an aircraft type at all.

CURRENT VALIDATION

Validation using NMT Results

The validation exercise for the 2014 contours used 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. Results were

obtained over the period September 2013 to September 2014. This resulted in over 33,000

individual aircraft measurements being used to review the assumptions made in the computer

modelling of the airborne aircraft noise.

To allow for any subsequent changes in the measured noise levels of the aircraft to be taken

into account, the validation exercise for the 2015 contours uses the most recent results from

the NMTs. Specifically the results for the period September 2014 to October 2015 have been

used which comprise over 31,000 individual aircraft measurements. This is slightly fewer than

last year despite the increase in movements as MP01 was not functioning correctly between

April and September 2015. Results from this period at MP01 were therefore not used for the

validation exercise. The lack of measured data in this period is not considered to have had a


significant effect on the validation exercise as data was still available for the majority of the

year.

The resulting average measured noise levels used for the validation exercises in 2014 and 2015

are given in Table A2.1 for the three most common aircraft types that operated in both the

2014 and 2015 summer periods. This shows that in general, the average measured noise levels

for these types have not varied by more than 0.7 dB with the exception of the Airbus A320 on

departure from runway 04.

Table A2.1: Measured Noise Levels used for Validation in 2015 and 2014

The 2015 exercise has considered the most common 6 aircraft types in the summer period of

2015, which were those mentioned in the table above in addition to the Embraer 175, the Let

L‐410 and the Fokker 70. These aircraft comprised around 97% of the summer period

movements in 2015. 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

Aircraft Type Operation

2015 Validation Measured Noise Levels (SEL dB)


Average Number Average Number

Airbus A319

Arrival Rwy 04 85.7 204 85.5 868

Arrival Rwy 22 90.0 1,810 89.9 2,170

Departure Rwy 04 90.1 653 90.4 877

Departure Rwy 22 87.7 904 87.6 2,209

Airbus A320

Arrival Rwy 04 86.1 232 86.7 341

Arrival Rwy 22 90.1 1,857 90.8 423

Departure Rwy 04 91.1 634 92.2 320

Departure Rwy 22 87.7 1,155 88.2 438

Bombardier Dash 8‐Q400

Arrival Rwy 04 82.8 1,098 82.8 2,560

Arrival Rwy 22 86.9 10,235 87.0 6,642

Departure Rwy 04 81.1 4,037 81.2 3,111

Departure Rwy 22 80.4 5,363 80.1 5,850


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.

Measured Results

The spread of results is illustrated in Figures A1.1 to A1.4. These show the distribution of

measured noise levels from September 2014 to October 2015 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 2015, the Bombardier Dash 8‐Q400 and the Airbus A319.

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

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 three most common aircraft

types in the 2015 summer period which comprised around 87% of movements.




INM Standard Assumptions (SEL dB)

Average Number Type Level

Airbus A319

Arrival Rwy 04 85.7 204

A319‐131

87.0

Arrival Rwy 22 90.0 1,810 90.0

Departure Rwy 04 90.1 653 87.9


Airbus A320

Arrival Rwy 04 86.1 232

A320‐211

87.4

Arrival Rwy 22 90.1 1,857 90.2


Departure Rwy 22 87.7 1,155 88.2


Arrival Rwy 04 82.8 1,098 SD330

82.2

Arrival Rwy 22 86.9 10,235 84.5

Departure Rwy 04 81.1 4,037 DHC6

82.1

Departure Rwy 22 80.4 5,363 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

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, Bombardier Dash 8‐Q400, Embraer 175 and Let L‐410, the measured

levels have not changed sufficiently to warrant a change from the validation used for the 2014

contours.

For the Airbus A320 on arrival the predicted noise levels are higher than the measured

averages by 1.3 dB at MP01 and lower by 0.1 dB at MP02, and so no modification has been


made, as was the case for the 2014 validation exercise. For departures the predicted noise

levels are lower than the measured averages by 1.7 dB at MP01 but higher by 0.5 dB at MP02,

and so a modification has been made. This is to increase the modelled number of departure

movements of this aircraft by a factor of 1.1. This is different from 2014 where a factor of 1.4

was used. Compared to 2014 the noise levels have decreased by 0.5 dB at MP01 and by 1.1 dB

at MP02.

The Fokker 70 is a new type that did not operate at GBBCA in 2014. 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 2.8 dB at MP01 and by 1.5 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. There were only 2 arrivals measured at MP01 and therefore the

modification is based on the MP02 results only. 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 of 0.8. The predicted noise levels for the

737800 × 0.8 are higher than the measured averages by 0.8 dB at MP01 but lower by 0.6 dB at

MP02.

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

2015 contours.

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 175 E175 737500 × 1.5 EMB175 x 1.2

Fokker 70 F70 737800 × 0.8 F10062 × 1.4

Let L‐410 L410 DHC6 × 2.0 SD330

Table A2.3: 2015 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 to a similar extent. For the Airbus A320, no modification

was necessary for arrival movements, and departure movements have been factored up.

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 175, 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,

with no modification needed.

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 suggest 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 slightly.

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.



Noise Levels (SEL dB)

Measured Average

INM Validated Prediction

Difference Predicted / Measured

Operation Weighted Average Difference

Airbus A319

Arrival Rwy 04 85.7 86.0 +0.3 ‐0.7

Arrival Rwy 22 90.0 89.0 ‐1.0

Departure Rwy 04 90.1 89.4 ‐0.7 +0.4

Departure Rwy 22 87.7 88.5 +0.8

Airbus A320

Arrival Rwy 04 86.1 87.4 +1.3 +0.4

Arrival Rwy 22 90.1 90.2 +0.1

Departure Rwy 04 91.1 89.8 ‐1.3 +0.2

Departure Rwy 22 87.7 88.6 +0.9


Arrival Rwy 04 82.8 83.7 +0.9 ‐0.4

Arrival Rwy 22 86.9 86.0 ‐0.9

Departure Rwy 04 81.1 81.1 +0.0 +0.1

Departure Rwy 22 80.4 80.6 +0.2

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 averaged, with the exception of arrivals by the A319 where the difference

is 0.7 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.

Comparing the results of the validation exercises in 2015 and 2014 for the most common

aircraft types operating in both years finds changes only for the Airbus A320. The validation

for the other two types remains unchanged.

A9920‐R01B‐DR 14 December 2015 A2.10

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 not be as accurate.

The latest contours have taken into account over 31,000 individual aircraft noise

measurements at GBBCA between September 2014 and October 2015. 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.


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

142 BAE146 DH4 DHC6/SD330(1)

319 A319‐131(1) E75 EMB175/737500(1)

320 A320‐211(1) E90 EMB190

321 A321‐232 E95 EMB195

717 717200 ER3 EMB145

727 717200 ER4 EMB145

734 737400 F70 F10062/737800(1)

73Y 737300 GRJ GV

AR8 BAE146 H25 LEAR35

BEC CNA441 JET CNA500

BET CNA441 L2J CNA500

BNI BEC58P L4T DHC6/SD330(1)

CCJ CL600 MP1 GASEPF

CCX GV MP2 BEC58P

CN1 CNA172 PA2 PA28

CN7 CNA750 PL2 CNA208

CNJ CNA500 S20 HS748A

DF2 FAL20 SF3 SF340

DF3 F10062

Table A3.1: INM Substitution List

Documents

GEORGE BEST BELFAST CITY AIRPORT AIRBORNE AIRCRAFT … · 2.2 Traffic Distribution by Aircraft Type The basis for the 2015 noise contours are the actual movements during the 92 day