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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
Figure A11019/R01/06: Comparison of 2016 and 2015 Daytime Noise Contours – 60 dB LAeq,16h
Figure A11019/R01/07: Comparison of 2016 and 2015 Daytime Noise Contours – 57 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: mail@bickerdikeallen.com 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
This drawing contains Ordnance Survey data © CrownCopyright and database right 2016.
DRAWN: CHECKED:
DATE: SCALE:
FIGURE No:
121 Salusbury Road, London, NW6 6RGEmail: mail@bickerdikeallen.com T: 0207 625 4411www.bickerdikeallen.com F: 0207 625 0250
REVISIONS
Belfast City AirportNoise Contours
2016 Summer Daytime Noise Contours
DR DC
15/12/2016 1:50000@A4
A11019/R01/02
LEGEND:2016 Noise ContourDoE Indicative Noise Contour
This drawing contains Ordnance Survey data © CrownCopyright and database right 2016.
DRAWN: CHECKED:
DATE: SCALE:
FIGURE No:
121 Salusbury Road, London, NW6 6RGEmail: mail@bickerdikeallen.com T: 0207 625 4411www.bickerdikeallen.com F: 0207 625 0250
REVISIONS
Belfast City AirportNoise Contours
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
This drawing contains Ordnance Survey data © CrownCopyright and database right 2016.
DRAWN: CHECKED:
DATE: SCALE:
FIGURE No:
121 Salusbury Road, London, NW6 6RGEmail: mail@bickerdikeallen.com T: 0207 625 4411www.bickerdikeallen.com F: 0207 625 0250
REVISIONS
Belfast City AirportNoise Contours
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
This drawing contains Ordnance Survey data © CrownCopyright and database right 2016.
DRAWN: CHECKED:
DATE: SCALE:
FIGURE No:
121 Salusbury Road, London, NW6 6RGEmail: mail@bickerdikeallen.com T: 0207 625 4411www.bickerdikeallen.com F: 0207 625 0250
REVISIONS
Belfast City AirportNoise Contours
Comparison of 2016 and 2015Summer Daytime Noise Contours63 dB L
DR DC
15/12/2016 1:50000@A4
A11019/R01/05
Aeq,16h
LEGEND:2016 Noise Contour2015 Noise Contour
This drawing contains Ordnance Survey data © CrownCopyright and database right 2016.
DRAWN: CHECKED:
DATE: SCALE:
FIGURE No:
121 Salusbury Road, London, NW6 6RGEmail: mail@bickerdikeallen.com T: 0207 625 4411www.bickerdikeallen.com F: 0207 625 0250
REVISIONS
Belfast City AirportNoise Contours
Comparison of 2016 and 2015Summer Daytime Noise Contours60 dB L
DR DC
15/12/2016 1:50000@A4
A11019/R01/06
Aeq,16h
LEGEND:2016 Noise Contour2015 Noise Contour
This drawing contains Ordnance Survey data © CrownCopyright and database right 2016.
DRAWN: CHECKED:
DATE: SCALE:
FIGURE No:
121 Salusbury Road, London, NW6 6RGEmail: mail@bickerdikeallen.com T: 0207 625 4411www.bickerdikeallen.com F: 0207 625 0250
REVISIONS
Belfast City AirportNoise Contours
Comparison of 2016 and 2015Summer Daytime Noise Contours57 dB L
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)
2015 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.
Aircraft Type Operation
2016 Validation Measured Noise Levels (SEL dB)
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
Bombardier Dash 8-Q400
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.
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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.
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Aircraft Type Operation
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
Bombardier Dash 8-Q400
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.
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APPENDIX 3
INM SUBSTITUTION LIST
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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
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