Heathrow Airport. Subject Matter: Investigation into breaches of the Noise Preferential Routes associated with Heathrow Standard Instrument Departures

Heathrow Airport An analysis conducted by NATS NSL on behalf of Heathrow Airport Limited (HAL) Subject Matter: Investigation into breaches of the Noise Preferential Routes associated with Heathrow Standard Instrument Departures Version 1.0 June 2017

Document Management Author Title NATS NSL Status Final Public Issue Version 1 Date June 2017 Document Protection Statement NATS is not a public body and therefore has no duty under Freedom of Information Act (FOIA) and Environmental Information Regulations (EIR) to release information. NATS does however appreciate that other organisations that receive NATS information could be subject to FOIA and EIR. With this is mind please do not release any NATS Protectively Marked Information without prior consent from the author of the information and exemptions could apply. The recipient of this material relies upon its content at their own risk, and it should be noted that the accuracy of any output is directly linked to the accuracy of the supplied data and information. Save where expressly agreed otherwise in writing and so far as is permitted by law, NATS disclaims all liability arising out of the use of this material by the recipient or any third party. Copyright NATS Ltd 2017 All rights reserved. No part of this document may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical photocopy, recording or otherwise without the prior permission of NATS. NATS (Services) Ltd, Registered in England 4129270, 4000 Parkway, Whiteley, Fareham, Hampshire, PO15 7FL All images Heathrow Airport Limited. NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 2 of 32

Executive Summary Aircraft taking off from some airports are required to follow specific flight paths called Noise Preferential Routes (NPRs) unless directed otherwise by Air Traffic Control. The NPRs at Heathrow, Gatwick and Stansted are designated and overseen by the Secretary of State for Transport (not the CAA), and were designed to avoid the over flight of built-up areas where possible. NPRs are integrated into a departure route for the aircraft to take from the runway until they reach the main UK air traffic routes. At the UK s major airports, the Secretary of State may prescribe 'Noise Preferential Routes' (NPRs) the path referred to above - to minimise noise disturbance: Aircraft following a departure route (called a Standard Instrument Departure or SID) after take-off are required to fly within 1.5 km of the centre of the route until they reach a defined altitude. This results in a swathe of airspace 3 km wide within which aircraft may be seen and heard under normal circumstances. This swathe is called the noise preferential route (NPR). The altitude below which aircraft are not allowed to deviate from this path is 4000 amsl (above mean sea level) unless authorised by Air Traffic Control or for safety reasons. This report investigates breaches of these NPRs at Heathrow. Executive Study Conclusions The study shows that the number of NPR breaches (note: any aircraft which exited the NPR below 4000 amsl (accurate to one foot) is recorded) is small in percentage terms. During the period of study in 2016 there were, on average, 500 breaches per month (20,959 departures per month on average) or approximately 16 breaches per day. What this study has not sought to do is categorise the NPR breaches into significant or minor. Heathrow Airport has asked for the study to be carried out without this distinction being made. The commonest cause (89.5%) is assigned to the Flight Behaviours category - aircraft speed 1 or Flight Management System (FMS) causing the aircraft to balloon outside the NPR. 1 Avionics, ARINC 424 coding, Standard Operating Procedures (SOPS) and human error in using selected speed or turning late. If it is human error, there may be an element where the procedures may not be all that clear and would need to be investigated. NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 3 of 32

Classification: Public Diagram 1 - Westerly NPRs Heathrow Diagram 2 -Easterly NPRs Heathrow NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 4 of 32

Table of Contents CONTENTS 1 INTRODUCTION... 6 1.1 OBJECTIVE... 6 1.2 BACKGROUND... 6 Noise Preferential Routes (NPRs) origin and definition of an NPR... 6 Ownership of NPRs at Heathrow... 6 Publication of the Heathrow NPRS... 7 Responsibilities of Heathrow:... 7 Permitted activities which may breach NPRs... 8 2 METHODOLOGY... 9 2.1 OVERVIEW... 9 2.2 REASONS BEHIND ISSUE... 10 2.3 CATEGORIES OF ISSUES... 11 2.4 EXPLANATION OF DIAGRAMS USED (SEE APPENDICES)... 12 3 RESULTS... 13 3.1 SAMPLE A... 13 In summary:... 13 Findings and hypotheses:... 13 BPK SID... 14 WOB 27 SID... 14 MID SID 27 only... 15 3.2 OTHER TYPES OF ANALYSIS (EXAMPLES) FOR SAMPLE A... 16 3.3 SAMPLE B EVERY NPR BREACH TRACK ANALYSED... 19 In summary:... 19 Overall compilation of issues:... 19 Findings:... 22 4 CONCLUSIONS... 24 4.1 SUMMARY TABLE... 24 5 NEXT STEPS... 25 6 APPENDICES... 26 6.1 APPENDIX A... 26 Examples of NPR Adherence... 26 6.2 APPENDIX B... 28 EXAMPLES OF EACH TYPE OF ISSUE... 28 6.2.0 Aircraft behaviours /speed - the aircraft carries excessive speed (or other issue) that causes the aircraft to balloon outside the NPR... 28 Weather Vector (Permitted Breach) -- Aircraft vectored to avoid thunderstorm or similar (weather on inside of the NPR)... 29 NATS Controller Issue - Aircraft vectored too early below 4000... 30 Pilot Error with FMS/Coding Aircraft FMS issue (probably speed) and Captain turns before the altitude specified by ATC is attained.... 31 Exited NPR below 4000 Aircraft follows NPR but fails to achieve 4000 by end of NPR... 31 Missed Approach causing another aircraft to be vectored below 4000 (permitted NPR Breach) 32 NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 5 of 32

1 Introduction 1.1 Objective This analysis will seek to discover and catalogue reasons for deviations from the Heathrow Noise Preferential Routes (NPRs) to inform the local communities and allow these communities to provide appropriate challenge to Heathrow Airport Limited (HAL) if required. NATS expertise is in identifying/proposing or suggesting systematic causes for breaches based on data analysis. This report is data driven to a significant extent and at this point will not comment on how these breaches could be addressed. For the purposes of providing information to local communities it is detrimental to present the data relating to absolute breaches for particular operators as it does not adequately indicate performance relative to size of operation, giving a skewed presentation of performance, therefore airline operators are not named. In addition, performance improvement is achieved through collaboration between airlines, NATS and operators and as such, prior to presenting a report to the community a "way forward" should be identified and agreed between all parties rather than presenting a "problem" with no agreed solution. To this end HAL and NATS have presented this report to the airlines prior to release to facilitate this. 1.2 Background The concept of NPRs was first established at a number of major UK airports in the early 1960s, but over time the exact definition and purpose of an NPR has become less than clear. The Government (DfT) issued Guidance to the CAA in 2014 2 seeking to provide some clarity therefore on what the Government considers is the purpose of an NPR and to establish a mechanism for adding new or amending existing NPRs at UK airports Noise Preferential Routes (NPRs) origin and definition of an NPR In the early 1960s, it began to be the custom to draw a line on the map to try and identify a preferred SID route for aircraft to fly in order to minimise their noise profile on the ground in the immediate vicinity of a number of dedicated routes. So in the initial stages of the SID, it would also be described as an NPR and share the same characteristics. It was recognised that not all aircraft would fly the SID perfectly, since changing weather patterns, the navigational accuracy of pilots and different aircraft types inevitably meant that some aircraft were flying some distance away from the specific line of the NPR. To compensate for the variance between the NPR line and the actual flight paths being flown by aircraft, it became an accepted practice to add a geographic swathe of airspace either side of some of the NPR lines. This had the effect of creating a containment area within which departing aircraft should ideally remain when flying below a given altitude as well as aiding the monitoring of compliance with track keeping. Ownership of NPRs at Heathrow NPRs at the designated airports which includes Heathrow - For many years, the Government has used Section 78 of the Civil Aviation Act 1982 3 to establish NPRs at the 3 largest London airports - Heathrow, Gatwick and Stansted which have been designated in law for the purpose of noise regulation (the so called noise designated airports ). At present, these NPRs can only be introduced or amended with the approval of the Secretary of State; 2 https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/269527/air-navigation-guidance.pdf 3 http://www.legislation.gov.uk/ukpga/1982/16/section/78 NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 6 of 32

Publication of the Heathrow NPRS Routes conforming to the NPRs at the designated airports are published by the Department for Transport in the UK Aeronautical Information Publication (AIP) 4. Although the likely amount of noise disturbance is best illustrated in a relevant noise footprint or contour published by airports in their annual reports/websites, maps depicting NPRs provide a simple means of conveying where departing aircraft are expected to be in the immediate vicinity of an airport. Further information can be found on the Heathrow Airport Website: http://www.heathrow.com/noise/heathrow-operations/departure-flight-paths Responsibilities of Heathrow: It is the responsibility of the airport operators to ensure the NPRs are used and the CAA Guidance concludes that: The monitoring by airport operators of the use of NPRs by their customers and their noise impact is to be encouraged; Heathrow airport has the ability to place restrictions on airlines who fail to work with the airport authority to solve any track keeping compliance issues. Heathrow track keeping (how well aircraft stay within the NPR up to 4,000ft) - On Heathrow s departure routes about 97.5% of all departures stay within the published routes. The exception is the Compton route from Runway 09R a departure route used during periods of easterly operations that heads west. Track keeping compliance is much lower on this route, and has been for many years due to the construction of the SID. Both the Government (DfT) and CAA are well aware of this. HAL monitor how well planes adhere to these routes and publish data on track keeping on a daily basis on their Operational Data website and quarterly and yearly in Flight Performance reports. Heathrow also publishes data related to track keeping including a performance table comparing airlines called Fly Quiet and Clean. 5 Data is published on the Heathrow website and the airlines strive to maintain or improve their position in the league table. 4 http://www.ead.eurocontrol.int/eadbasic/pamslight- 5FC496AAF4B193339236FDE45CA13EF0/7FE5QZZF3FXUS/EN/AIP/AD/EG_AD_2_EGLL_en_2016-12-08.pdf 5 http://www.heathrow.com/noise/making-heathrow-quieter/fly-quiet-and-clean NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 7 of 32

Year Departure routes (all) excluding Easterly Compton % 2007 96.6 2008 97.1 2009 97.5 2010 97.7 2011 97.9 2012 98.0 2013 97.5 2014 98.0 2015 97.7 Figure 1: NPR compliance Yrs. 2007-2015 Permitted activities which may breach NPRs On occasions planes are directed to take a different route by Air Traffic Control (ATC) and to leave the NPR below 4,000ft amsl (note: the technical height is 3917 as Heathrow is 83 above mean sea level, and this is what the NPR is measured against as you will see in the flight track data boxes in Appendix A, but we will refer to 4000 amsl for ease of reference hereafter). This could be for a number of reasons such as thunderstorms, severe weather conditions or another aircraft such as a police helicopter that is flying within the departure route. Pilots may also request to leave the NPR for safety reasons and do so by making a request to ATC. NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 8 of 32

2 Methodology 2.1 Overview The methodology applied, for initial investigations, was as follows: Two samples of representative size were selected with the help of Mr Peter Rafano (Peter is the HAL expert on noise and track keeping and is a world renowned expert on the Heathrow ANOMS (Noise and Track Keeping System.) Sample A The first sample (Sample A) was all departures from the period 1 September to 30 September 2016 inclusive to assess workload required and to test the NATS/HAL ability and resource required to investigate the issues. This sample contained 19,882 departures of which 495, excluding Runway 09R Compton (09R CPT) as discussed in 1.2.4, were NPR Breaches. The sample was looked at in batches to see if trends could be identified. It also allowed hypotheses to be developed and tested against the individual track examination in Sample B. Sample B The second sample (Sample B) was examined by looking at every track that was believed to be an NPR Breach. This sample included all departures between the period 24 October & 29 November 2016 inclusive excluding 09R CPT Departures. How much of a breach is to be called a Breach? Every aircraft that exited the NPR below 4000 Above Mean Sea Level (AMSL) was examined by a team of experts. Issue Assignment Where a reason could be assigned as the likely issue on first examination this was applied. A sample was stress tested by the experts to provide evidence supporting this assignment. Further Investigation Where further information was required, the flight data was submitted to NATS for further investigation. NATS work included review of ATC radar recordings and ATC radio telephony by an ATC Investigator. NATS has worked closely with the CAA Safety and Regulation group: although there are no safety implications with NPR breaches, NATS takes all ATC matters seriously and investigates in order to prevent safety issues developing. NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 9 of 32

2.2 Reasons behind issue The airlines flight plan determines the route and the appropriate SID (and encompassing NPR) subject to internationally agreed flight planning documents (essentially route maps with rules) ATC (nationally or internationally) may reject this route if it is incorrectly filed or offer another route to balance the network (usually for safety reasons due to capacity of the sector handling the aircraft) or if the route is obstructed (weather or war or special events etc.) Local ATC will confirm this route on first contact to remove ambiguity and so remove the possibility of error. An aircraft s ability to follow an exact route is affected by factors such as: Navigational equipment; The type and weight of aircraft; Weather conditions particularly winds that may cause drifting when aircraft are turning. When airborne it should remain within the swathe of the NPR (and the 1.5km either side of the centreline is there to allow for the factors above) unless ATC authorises it to leave the NPR. ATC cannot intervene (instruct the aircraft to do something when climbing) below 500 at all and, except in emergency, not below 1800-2100 otherwise. After this ATC can intervene and offer vectors to any aircraft below 4000 amsl for safety reasons (normally weather or safety related ATC interventions usually but not exclusively related to other aircraft). Common examples are thunderstorms, police helicopters, airspace infringements by light aircraft requiring ATC intervention with other aircraft, aircraft in emergency and aircraft on a missed approach (not on a SID but may be seen by communities as a departure off the SID ). After passing 4000 amsl ATC may vector the aircraft as required. As usual with any human in the system errors may be made however minor: The coding house inputting the SID (NPR) into the aircraft Flight Management System (FMS) may have made an error very unlikely and unlikely to be a significant error otherwise ATC would notice but enough to breach an NPR for example the turn may just take it outside the swathe. Similarly, the aircraft speed (for a variety of reasons) may result in the turn not being adhered to. The pilot may have made an error with inputting into the Flight Management System (mainly speed). The pilot may make an error in flying the aircraft if not using automatic controls (although automatic controls may not always be as accurate as manual flying in every case speed settings etc. may contribute to track error in both circumstances) or reading back an instruction correctly but not performing the instruction correctly or incorrect read back and performing the wrong instruction. The controller may make an error in passing an instruction or not picking up an incorrect read back by the pilot either in the departing aircraft or another aircraft causing the departing aircraft to be turned for safety reasons. Light aircraft may inadvertently enter airspace through pilot error causing other aircraft to be vectored away the airspace protecting Heathrow (LTMA) has had about 260 of these infringements this year to date. NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 10 of 32

Missed approaches normally once or twice a day an aircraft making an approach to Heathrow will elect or be instructed not to complete the landing and execute a missed approach (also known as a go-around). This is perfectly normal and will be due to a variety of issues such as wind direction, weather, runway availability, birds, passengers not seated etcetera. These aircraft do NOT follow the SID and therefore are not in an NPR. This report will not investigate these aircraft but will capture any deviation by another aircraft as a result of the missed approach. Human error in Air Traffic Management (ATM) (as in any complicated mechanism involving humans) is driven as low as possible and the ATC/Airlines system operates a just culture 6 to encourage reporting of and learning from error. This is why ATC have such strict examiners (continual assessment and cross checking and testing), pilots use checklists and cross checking and simulation, airspace designers use cross checking and peer review and aircraft designers use wind tunnels etc. One of the key issues with NPR compliance is due to FMS Flight Behaviours. The SIDs and their associated NPRs were designed in the 1960s. Modern aircraft fly far more efficiently than those of 50 years ago in that that they can climb and accelerate quicker meaning that the NPR is no longer representative of typical flight behaviours. Another issue is that an aircraft's Flight Management System recognises the SID but not the NPR, meaning that an aircraft may safely comply with the departure procedure without complying with the NPR and the pilot would not realise this is the case. 2.3 Categories of Issues Sample A produced the following likely categories which were applied to Sample B a) Aircraft Behaviours 7 or weather effect b) Pilot error c) Failure to maintain sufficient altitude by end of NPR d) ATC error e) ATC instruction for safety or weather reason (permitted NPR excursion) f) ANOMS 8 error g) No explanation did not fall into above categories or needed further investigation in Sample B 6 "Just Culture" is a culture in which front-line operators and others are not punished for actions, omissions or decisions taken by them which are commensurate with their experience and training, but where gross negligence, wilful violations and destructive acts are not tolerated 7 There are no speed controls hard-coded into the procedures (except the usual 250kts max below FL100) so ARINC 424 coding will have no impact on speed - the avionics can. Standard Operating procedures can also have an impact on speed or it could be human error in using selected speed or turning late. 8 ANOMS the Heathrow Noise and Track Keeping Computer there was one error identified attributed to ANOMS caused by an early request by the investigating team for data which meant ANOMS had to estimate the track and the aircraft was shown to have left the NPR. ANOMS corrected itself appropriately when it next ran the actual data and put the aircraft back into the NPR. NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 11 of 32

2.4 Explanation of diagrams used (see Appendices) The diagrams used show the track of an aircraft with multi-coloured sections indicating height above sea-level. The two runways are shown in each case with the northerly runway being 27R/09L and the southerly runway 27L/09R. The NPR is shown as a 3km swathe bounding the centreline of the relevant SID. There is data block showing information on the aircraft and the time/altitude (height) at which it left the NPR. The data block is attached to the track of the aircraft where it left the NPR. The key altitude is 3918 (yellow to purple) equivalent to 4000 amsl. In the bottom left corner is a scale marker (normally 2 nautical miles 9 ) with a North Marker (compass). 9 A nautical mile is a unit of measurement defined as exactly 1852 meters (about 6,076.1 feet or 1.1508 statute miles). Historically, it was defined as one sixtieth of the distance between two parallels of latitude separated by one degree. Today it is an SI derived unit, being rounded to an even number of meters] and remains in use for both air and marine navigation. The derived unit of speed is the knot, defined as one nautical mile per hour. The geographical mile is the length of one minute of longitude along the Equator, about 1,855.325 m on the WGS 84 ellipsoid. (Wikipedia) NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 12 of 32

3 Results 3.1 Sample A In summary: There were 19,882 departures during the time period (one month September 2016) excluding 09R CPT Departures. There were 495 occasions when an aircraft left the NPR on all Heathrow SIDS below 4000 amsl excluding CPT 09 (2.48%) Twenty-nine (29) aircraft on all SIDS received vectors as recorded by NATS and are permitted breaches of the NPR for safety or weather. These are, however, included at this stage in the separate SID analysis below. Batch analysis (looking at visual data as well as actual data but at a distance to look for trends) DET SID Findings and hypotheses: DET27 DET09 There were 215 Aircraft on the DET SID Departure route that left the associated NPR. Mainly A320/A380 fleet narrow body Airbus and wide body Airbus) and B787 fleet (Dreamliner) multiple operators. Hypothesis A Investigate whether speed or coding on Runway 27 SIDS is causing ballooning around edge We saw that the majority of breaches were on the outside of the turn curve. 10 Hypothesis B Check needed on 09DET to ascertain whether there was any early vectoring against Gatwick outbound at night but unlikely to be ATC vectoring on Runway 27. Gatwick departures converge towards Heathrow DET 09R departures further down the route. 10 See Appendix 6.2.1 for an example NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 13 of 32

BPK SID BPK27 BPK09 109 aircraft Hypothesis Possible operator fleet issue with coding or speed - we saw that the majority of breaches were on the outside of the turn curve. The second issue is slow climbers not making 4000 by the end of the NPR. This issue is generating small numbers. WOB27 WOB 27 SID 43 Aircraft Hypothesis 43 Aircraft Hypothesis Possible operator fleet issue similar to above. Overall these three SIDS account for 360/495 of the NPR Breaches below 4000 the remainder are covered in the main by: NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 14 of 32

MID SID 27 only 106 Aircraft MID27 Hypothesis A few were notified as weather/safety but the majority are Heavy (wide body) aircraft after 21:30 at night. The authors speculate that about 80% are likely to be Flight Behaviours issues. Some of these appear to have track keeping issues combined with other reasons such as deviation for ATM reasons (be it pilot error or ATC error and this is yet to be determined). Possible Trend: there may be a time correlation (the inbound Gatwick stream from the south is building at this time of night) which might lead to anticipation of altitude attainment by controllers to ease workload and requests to increase climb (see Figures 1 and 2 below) to jump the opposite direction aircraft. 0600-1000 1001-1400 1401-1800 1801-2200 2201-0200 Figure 1 Time trend for MID (four hour sections) all aircraft types NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 15 of 32

40 35 30 25 20 15 10 5 0 Heavy Aircraft Medium Aircraft Figure 2 Heavy (wide body) vs. Medium (narrow body) aircraft for MID (four hour sections) General 29 aircraft were on other SIDS but no obvious trend was observed therefore no hypothesis could be generated. 3.2 Other types of analysis (examples) for Sample A We worked through different techniques of data analysis to formulate these hypotheses ranging from Pie Charts, Excel spread sheets, batch analysis (looking at the overall picture) to actual radar tracks and radio recordings. A320 A330 A340 A380 B737 B747 B767 B777 B787 Other Figure 3 Aircraft Type Sample A (495 aircraft) NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 16 of 32

09RBPK 09RBUZ 09RGAS Figure 4 SID Sample A Runway 09 (9 aircraft) - only 3 SIDs had NPR Breaches 27LBPK 27LCPT 27LDET 27LGOG 27LMID 27LWOB 27RBPK 27RCPT 27RDET 27RGOG Figure 5 SID Sample A Runways 27L and 27R (486 aircraft) NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 17 of 32

The next two Figures are examples of the analysis that forms the basis of the Hypotheses when combined with batch track analysis. A320 Family A330 A340 A380 B737 Family B777 B787 Figure 6 Aircraft Type on 27L BPK (52 aircraft) Figure 7 Batch Analysis Tracks 27L BPK NPR Breaches in September NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 18 of 32

3.3 Sample B every NPR Breach track analysed In summary: There were 22,036 departures during the time period 24 October & 29 November 2016 inclusive excluding 09R CPT Departures. There were 504 occasions when an aircraft left the NPR on all Heathrow SIDs below 4000 amsl excluding CPT 09 (2.28%) 28 aircraft on all SIDs received vectors as recorded by NATS and are permitted breaches of the NPR for safety or weather. 6 aircraft breached the NPR linked to a missed approach and are permitted breaches of the NPR for safety. Overall compilation of issues: 3.3.2.1 General Issues Breakdown (see Appendices for examples) 6 6 5 8 28 450 FMS issue Missed Approach Link NATS Issue NPR Below Pilot Error Weather Figure 8 NPR Issues NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 19 of 32

3.3.2.2 Aircraft type Breakdown A320 Family 42 36 19 17 4 43 2 2 176 B787 B777 A380 B747 58 A340 A330 140 B737 Family Others A350 B757 B767 Figure 9 Aircraft type 6 2 3 09LGAS 4 09LMID 9 09RBPK 09RBUZ 5 4 09RDET 09RGAS 09RMID Figure 10 Runway 09 SID Combined NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 20 of 32

37 5 20 3 0 27LBPK 27LCPT 27LDET 27RGOG 27LMID 27LWOB 187 7 16 0 53 27RBPK 27RCPT 27RDET 2 27RGOG 27RMID 140 27RWOB Figure 11 Runway 27L (top) and 27R (bottom) SID NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 21 of 32

Findings: 3.3.3.1 DET SID This is the commonest SID/NPR to be breached, accounting for 327 of 504 breaches observed in the time period (64%). The commonest aircraft types are A320/A380 fleet and B787 fleet multiple operators and all likely to be speed issues. Hypothesis A- Hypothesis confirmed Hypothesis B - Hypothesis not proved No evidence of NATS early vectoring issues. 3.3.3.2 BPK SID This is the third commonest SID/NPR to be breached, accounting for 45 of 504 breaches observed in the time period (8.9%). Hypothesis A- Hypothesis confirmed but not limited to single operator fleet Hypothesis B - Hypothesis confirmed The second issue is slow climbers not making 4000 by the end of the NPR. This issue is generating small numbers (5 of 504) only. 3.3.3.3 WOB SID Only 12 NPR breaches occurred, which is less than expected compared to September 2016. 7 of the 12 breaches were by one operator but no definite trend can be observed from such small numbers. Hypothesis A - Hypothesis not proved but possibly confirmed 3.3.3.4 MID SID 27 only This is the second commonest SID/NPR to be breached, accounting for 90 of 504 breaches observed in the time period (17.8%). As a reminder, the hypothesis and trend was: A few are notified as weather/safety but the majority are Heavy aircraft after 21:30 at night. The authors speculate that about 80% are likely to be coding/speed issues. Some of these appear to have track keeping issues combined with other reasons such as deviation for ATM reasons (be it pilot error or ATC error and this is yet to be determined). NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 22 of 32

Possible Trend: there may be a time correlation (the inbound Gatwick stream from the south is building at this time of night) which might lead to anticipation of altitude attainment by controllers to ease workload and increase climb. The actual results were: 82% were likely to be Flight Behaviours or Speed issues. 6.6% were permitted vectors for weather issues. 2.2% were NPR breaches exiting the end of the NPR below 4000. 7.7% were determined to be likely pilot error 11 /FMS issue. There were no NATS issues observed for MID 27 SIDs (instructing pilots to comply with a vector and leave the NPR below 4000 without a permitted reason) but there had been 4 such issues observed and investigated in September which were referred directly to the ATC unit concerned. Overall, there were 5 NATS issues on all the SIDs excluding MID27 in Sample B (1%) and all have been investigated in November following referral directly to the ATC unit concerned. The instances in September involved specific briefings for the controllers concerned. All controllers at the unit were briefed in November 2016. Investigating time trends showed there were 38 NPR breaches post 21:00 and all were by wide body aircraft. There was no correlation with the Gatwick inbound stream increasing the likelihood of inappropriate vectoring. Hypothesis A - Hypothesis confirmed there is a trend but - Trend Correlation in time and weight category of aircraft but all were FMS or speed issues not connected to Gatwick inbounds. 11 This is difficult to pin down without interviewing the pilots concerned. ATC passed an instruction that was conditional on an altitude being attained before it should be acted upon by the pilot. All 7 aircraft received this conditional clearance but due to FMS/coding also being in play it was not possible to separate out the issue: There were absolutely no safety issues involved. NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 23 of 32

4 Conclusions The study has shown that the number of NPR breaches (note: any aircraft that exited the NPR below 3917 (accurate to one foot)) is relatively small in percentage terms The total percentage for the Sample B on all Heathrow SIDs below 4000 amsl excluding CPT 09 is 2.28%. In terms of actual numbers for the Sample B on all Heathrow SIDs below 4000 amsl excluding CPT 09 this figure was 504. Regardless of the percentage the actual numbers are important to both Heathrow and the communities surrounding Heathrow. The following trends were noted: The DET 27 SID (64% of breaches) appears to create issues for a significant proportion of the airlines using the Heathrow DET SID especially those using the newer aircraft types. This is likely to be due to excessive speed being retained during the initial turn. The MID 27 SID (17.8%) appears to result in similar issues for the heavier aircraft regarding speed but there may be a complicating factor for carriers operating heavy wide body aircraft after 21:00 which has not yet been identified and will be followed up with the airlines. It may be that it is due to the aircraft type rather than the time as the majority of aircraft after 21:00 are wide bodies. 12 4.1 Summary table Observed Number in Sample B Percentage FMS 450 89.5 Weather 28 5.6 Pilot 8 1.6 Missed Approach Link 13 6 1.2 NATS 6 1.2 NPR Below 5 1.0 12 Aircraft that do not receive a vector are likely to be restricted to 6000 for a significant proportion of the early part of the SID and even to the end of the SID which might compromise the impact on communities further afield from Heathrow 13 Example and explanation see 6.2.6 below NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 24 of 32

5 Next Steps Heathrow Airport is committed to reducing aircraft noise. The specialist Flight Performance Team at Heathrow will continue to work closely with the airlines that use Heathrow and with NATS (the ATC provider) to monitor and where possible reduce NPR breaches and increase compliance. Progress will be shared with the Heathrow Community Noise Forum and sub groups. NATS will continue to reinforce the message to its controllers and monitor compliance with the Heathrow team. The main issue with NPR adherence is that the NPRs and SIDs have not been updated since the 1960s making it increasingly difficult for aircraft to fly efficiently on departure whilst still adhering to the NPRs. One illustration of this is that the worst performing aircraft type relative to the number of movements is the most up-to-date: Boeing 787. Allowing the FMS to fly the aircraft as designed is the most efficient solution - in terms of fuel, emissions and noise - but this is not possible in the majority of cases if the aircraft is to adhere to the NPR. Therefore, the ultimate solution is to modernise the departure procedures to better reflect the capabilities of today's aircraft. NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 25 of 32

6 Appendices 6.1 Appendix A Examples of NPR Adherence a) The aircraft remained fully within the NPR until; over 4000 after which the ATC Controller vectored the aircraft to allow that aircraft or another aircraft to climb higher than 6000. NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 26 of 32

b) The aircraft remains in the NPR and on the SID to the end of the monitored track. NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 27 of 32

6.2 Appendix B Examples of each type of issue There is considerably less data for Easterly Departures (Runway 09) but we have included examples where available. 6.2.0 Aircraft behaviours /speed - the aircraft carries excessive speed (or other issue) that causes the aircraft to balloon outside the NPR NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 28 of 32

(Note this aircraft was 50 metres out of the NPR but is still recorded wingspan 60.3m) Weather Vector (Permitted Breach) -- Aircraft vectored to avoid thunderstorm or similar (weather on inside of the NPR) NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 29 of 32

NATS Controller Issue - Aircraft vectored too early below 4000 NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 30 of 32

Pilot Error with FMS/Coding Aircraft FMS issue (probably speed) and Captain turns before the altitude specified by ATC is attained. Exited NPR below 4000 Aircraft follows NPR but fails to achieve 4000 by end of NPR NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 31 of 32

Missed Approach causing another aircraft to be vectored below 4000 (permitted NPR Breach) This aircraft was turned early by the TWR controllers in response to an aircraft executing a missed approach - A missed approach is a controlled and safe procedure initiated by the Pilot or ATC involving the aircraft aborting its approach to land and either returning to the inbound stream or diverting. 14 14 A missed approach is executed when the pilot or ATC feels that a safe landing cannot be accomplished. This may be for many reasons: a blocked runway, the pilot (in fog or low cloud) may not have acquired visually the runway before his decision height literally the height he/she has to decide whether he can land or not, a passenger not seated, weather issues etc. the list is long NATS (Services) Limited 2017 (except where explicitly stated otherwise) Page 32 of 32