Draft airspace design guidance

Since there is no other place at which to make general remarks about the entire consultation, we start by setting out, trenchantly, our reflection on the overall package. 1) Participation has been hugely onerous: few "lay people" would want or wish to assimilate a total 280 pages of dense aviation geekery in order to be able meaningfully to influence the formulation of a decision-making process which might contribute to blighting their lives and devaluing their homes, yet you provide no accessible entrée by which they might at least express a top-level view on the less technical aspects. 2) The first page of questions requires the participant to specify which of the official regions of the UK they live in, yet the list is faulty since it should specify "London and the South East", and in any case why not just ask the county in which they live and then get the computer to assign it to a region? You may well find that respondents who make significant mention of Luton Airport have assigned themselves to "South East" rather than "East of England" because of the ambiguity of the term "South East". Similarly, as a representative of a community group of hundreds of people from all over the area, why can’t I find a "community group representative" category rather than being advised to respond as "a resident", which implies an individual rather than a group weighting? And what if someone is a resident and also an airline passenger? 3) Your choice of words for the multiple choice questions is questionable. Q1 asks whether the guidance is "Comprehensible" in the sense that it is clear what happens. Q2 then asks whether it is "Transparent" partly in the sense of being well explained, which of course is the same as asking whether it is comprehensible. 4) There are innumerable text boxes over a large number of web pages, yet for those representatives wishing to produce a draft response for review by, say, a committee there is NO facility to produce a document or PDF version of a working draft for review. This is a fundamental oversight and demonstrates lack of courtesy and little experience with running public consultations - even the DfT got this aspect right. 5) Much of what is being explored overlaps in time and scope with the DfT consultation on aviation policy, and in some places appears to assume or depend on the outcome of that separate consultation. This is confusing and unhelpful. 6) The sheer volume of material makes it extremely tedious to assimilate, and we suspect that little value would actually be lost if the number of words was halved, and so we suggest some effort be applied to condensing the process narrative. 7) We see a clear distinction between matters which go to safety and technical aviation requirements which cannot really be avoided, and matters which go to the impact on both people on the ground and the environment. Could the two not be separated more clearly so at least the "negotiable" items or process are more accessible to ordinary people? Otherwise we would argue that the entire process is unfairly biased against effective involvement by the people which are going to be affected by its outcomes, which is undemocratic. 8) Much of the process relates to seeking transparent dialogue between airports and those they affect. BUT (a) if this is a new approach then the CAA has clearly failed in the past to inculcate a culture of dialogue and transparency in the industry it regulates; and (b) there is only passing reference made to the key role of Airport Consultative Committees which are intended by government to play an important role in aviation/community dialogue. Much of what is discussed in this consultation can and should be taking place with the assistance of suitably empowered and effective ACCs. We would like to see their role made more explicit and a means developed regularly to review their effectiveness. 9) It must be clear even from the government's half-hearted attempts to produce policy words which now give a faint nod to the blighting effects of aviation noise, and from the large numbers of local organisations which have signed up to the Aviation Community Forum's May 2017 statement on aviation policy, that the wind of public opinion is changing, and the CAA is often perceived as being on the wrong runway. Putting it simply: (a) there needs to be a policy which sets clear targets for noise REDUCTION at all major airports; (b) that an independent and empowered regulator is required to enforce this objective; (c) that if aviation noise cannot or will not be brought below acceptable thresholds then the airports should pay meaningful compensation to local communities in exactly the same way as noise from busy roads is compensated. 10) Because of its onerous complexity, an airspace change will take 2-3 years. A lot can happen in 2-3 years in terms of airport traffic (example: flights from Luton on its R26 Match/Detling route increased by 50% in just 2 years 2013-15). We understand that one reason for slow ACPs is that the CAA only has limited resource to review them. This must be rectified. Any ACP designed and agreed locally to benefit people on the ground should be able to be fast-tracked, and maintaining a parallel pipeline of rapidly but effectively progressed ACPs of this type is key to rebuilding trust. The CAA must resource a team of reviewers, should be more hands-on at local level during ACPs, and should assess the end-to-end process to identify ways in which it can be speeded up without losing the key community input. Having said all that, we welcome a revised airspace change process which emphasises stakeholder engagement and transparency. We look to the CAA to deliver a regulatory role which does more than just facilitate expansion in aviation. The balance needs to be tilted towards reducing rather than continuing to increase aviation noise impact. We now proceed with our more specific and constructive responses. We have reservations about Transparency at the nub of decision-making. Taking for example Appendix G 7.1 p193, a key decision is: "Has the noise impact been adequately assessed and presented in the consultation material and the final submission to the CAA, taking account of scalability and proportionality?" On what basis and from what perspective does the CAA decide this - and indeed on what basis is the CAA best placed to decide this? CAA is associated with prioritising growth in aviation, not with protecting the interests of people on the ground, and we would insist on adequacy of noise assessment being a key role for an independent ICCAN with power to intervene in the ACP if standards are not met. Re para B59, assessment of overflight in CAP1498 is a belated CAA step in the right direction, and we would strongly support use of the 48.5 degree definition. Government policy "To limit and where possible reduce the number of people in the UK significantly affected by aircraft noise..." is tenuous to say the least, and the continued reliance on inadequate, discredited and outdated LAeq16h noise measures (see the work of Flindell and others) in both the recent DfT consultation and in the CAA's environmental assessment criteria do not inspire confidence that people on the ground are adequately being factored in to the essential process of making fair and balanced decisions about the increasing burden of noise and pollution produced by the growth in aviation. We would request that production of Nx contours is mandatory not discretionary; that charts showing expected numbers of flights (departures and arrivals) per hour for day and night are mandatory also; and that all charts should show progression over time. We suggest that the balance of decision-making between ground noise impact and fuel burn should take more account of the negative health impacts of aircraft noise, particularly noise at night, and give reduction of noise impact close to airports more priority in decision-making. Few UK airports have been deliberately located so as to minimise the detrimental effects of aircraft noise, and the CAA needs to protect the public more effectively from this growing burden as it considers airspace change. We also request that Airspace Change Proposals should be prioritised if stakeholders agree that they target mitigation of ground noise rather than growth in aviation: 2-3 years is a long time to wait for mitigation.

The further an airspace change sponsor gets into the process before consulting stakeholders, the less likely they will be to be prepared to modify what they propose in order to take account of stakeholder input. Since it is unreasonable to expect a community group or even a local or county council to be able to sponsor an ACP, airport operators will probably drive the process more often than not. To avoid plans developing too far from a single (aviation) perspective we request that the new ACP should mandate that stakeholders must be included in meaningful two-way discussion right from the start, even before the Definition is presented. References made throughout to not overflying populated areas below 7000ft, not vectoring before 4000ft, or discounting aircraft above 4000ft in noise modelling are too generalised. Factors such as ambient background noise, rural/urban environment, size / weight / configuration of aircraft, and engine type, all have an impact on perceived ground noise from flights at 4000ft or 7000ft. The relevant factor is not primarily the altitude but the ground noise of the flights under consideration. We request that the use of 4000ft and 7000ft thresholds in general be revisited so that more meaningful thresholds can be set taking account of the context. Incremental noise on the ground is a far better indicator of annoyance impact than altitude alone.

Given that the sponsor will often be an airport operator, an airspace change "statement of need" will reflect an aviation perspective and priority. The initial discussion meeting should therefore include community stakeholders and/or the local Airport Consultative Committees to ensure that such stakeholders have an appropriate level of influence and visibility. We request the process of drawing up the statement of Need be redrafted to ensure that stakeholders are included in the consideration of what is appropriate for community engagement, rather than this being discussed behind closed doors between the CAA and the sponsor. The reference in para 94 to an approach "which both meets its own (ie the sponsor's) needs while ensuring a proportionate impact on those affected" strongly implies that the interests of community stakeholders are secondary to the needs of aviation. Please redraft to make clear that the best and fairest balance between the needs of the sponsor and the interests of the communities should be achieved. There is a second important point regarding transparency and accessibility. It will be unclear to many community stakeholders outside the aviation industry the degrees of freedom which may be available in producing a design. For this reason they will be utterly dependent on information from the sponsor, which puts them at a disadvantage. We believe it is essential for an independent third-party body such as ICCAN, or third-party independent advisers selected by stakeholders but funded by the sponsor up to a defined amount, should be a key part of the process. We also point out that although the CAA appears to assume ICCAN's form and status, that itself is the subject of review in the recently closed DfT consultation and so is not yet decided. We do not see how ICCAN can deliver on the essential role of ensuring that the issues relating to aircraft noise impact are adequately taken into account, if it is part of the CAA. ICAAN should be independent of the CAA, and given powers to intervene and require change to ensure a fairer balance going forward between the interests of the aviation industry and those affected by its inevitable noise and pollution. Finally, it is clear (for example from the Luton Airport R26 RNAV implementation) that the assumption that "flight concentration is always best" is not necessarily correct. Where a narrow corridor exists between two communities, the use of concentration rather than dispersal can paradoxically serve to increase the number of people affected by aircraft noise. GPS-based navigation technology is being introduced to facilitate the cramming of more and more aircraft into the already crowded skies. It does not follow that concentration, or even dispersed concentration, best mitigates noise impact in all circumstances, yet "random dispersion" cannot be achieved with the latest tools. Again, an independent ICCAN would be better placed to take a view case-by-case and advise.

Para 125 refers to the Environmental criteria. Whilst a range of parameters are mentioned, there is over-reliance on the discredited use of long-duration (8h or 16h) LAeq averaging. People are affected by and sensitised by individual noise events and the frequency of those events over smaller periods of time than 16 hours. See the work of Flindell and others (for example "Understanding UK Community Annoyance with Aircraft Noise", which can be found at http://www.hacan.org.uk/resources/reports/Understanding_UKCommunity_Annoyance_for_2M_Group_final_03092013.pdf ) This builds on the work of ANASE, which itself questioned an over-simplistic approach. LAeq 16h is a thoroughly discredited measure, as the Flindell document states: "From a purely research evidence perspective, it is surprising that UK policy-makers continue to base their understanding of numbers of people affected by aircraft noise on out-of-date, biased, non-independently-reviewed research – especially when there is available much more up-to-date evidence of UK residents’ views on aircraft noise that is consistent with all other recent and substantive pieces of research in the UK and elsewhere in Europe." We would improve the draft guidance by ensuring that more representative measures as used. Three measures should be considered: 1) an LAeq value measured over a much shorter 1 hour period during the typically busiest hour of operations in summer and an indication of the number of individual hours during the day in which this averaged noise would exceed a threshold of annoyance (with a lower threshold at night than during the day) 2) the peak LAmax and average LAmax of flights under a flight path at a specified distance (say 2 miles) from the airfield 3) the Nx contours Finally, it is not clear in general what the process of developing a solution would be if an ACP involved more than one airport. For example, the long-standing problem of westerly departures from Luton being held low by departures from Heathrow flying above them requires coordination between both airports. Stakeholders at Luton have no visibility whatsoever of the discussions with Heathrow and NATS to resolve this and it is not clear what visibility would be provided during an ACP involving multiple airports.

Para 138 emphasises the key importance of the consultation, and the CAA is designated as the judge of how accessible the consultation is. Taking this particular consultation as an example, we wonder whether the CAA is best placed to decide how effective a proposed consultation would be? Please incorporate instead reference to best practice from an independent and suitably qualified third party source. In para 149, rather than an independent reviewer being an option, the mandatory use of an independent facilitator would be appropriate in this role. Aviation is fraught with acronyms, jargon and processes unfamiliar to the lay person. Sponsors will know the jargon but often cannot bridge the communication gap. Local Councils engaging on behalf of communities is no longer something which can be relied on given resource constraints, and again a knowledge-gap often exists. In the interests of fairness and transparency, independent assistance from ICCAN or another third party in facilitating full participation would therefore be essential. In terms of any trials conducted before consultation and reported in consultation documents, it is essential to ensure that an appropriate level of analytical rigour has been applied. This does not just mean showing standard deviations and confidence intervals. It is well known that weather in general, and air density in particular, has a significant impact on aircraft climb performance and hence ground noise. Unless this effect is factored in to any conclusions drawn from flight trials where "before", "during" and "after" sample periods may span a number of months, conclusions can be misleading. The fact that CAA has not provided clear guidance on this again indicates the need for independent review of consultation material by a competent third party. We request more consideration of the basis for scoring the consultation results. Should a small number of people badly affected by a proposed change be outvoted by a larger number of people who may slightly benefit? Should a town outvote a rural village if a choice has to be made about where noise impact should fall? Should an AONB be safeguarded rather than the tranquillity of people's gardens? What is more economically valuable - people flying to and from stag parties in Europe, or enabling residents who work in the local economy close to an airfield sleep at night? Aviation impact is curtailed or not curtailed as a result of government policy, which at present appears to favour unconstrained growth excused by fig-leaf statements such as "minimising the number of people affected". The CAA should request clarification of such meaningless aspirations. Ultimately the "motorway in the sky" has to be recognised for what it is, and treated accordingly in legislation.

As drafted, the process gives the change sponsor carte blanche to decide what changes to make as a result of consultation responses, in an overall process which is supposed to be transparent and to involve stakeholders. The CAA should require sponsors to participate in further discussion with stakeholders in the light of the consultation responses. Again, an independent third-party facilitator would provide a useful advisory conduit.

The call-in threshold (for example in relation to airport capacity expansion) can clearly be abused by making incremental applications spaced over a period of years, each just beneath the call-in criterion. Witness capacity increase applications for 9 million or 9.5 million passengers per annum in the last 5 years. We request that the CAA lobby the government to make clear that any submission will be reviewed in the light of previous submissions by the same sponsor in the preceding 10 years, and if there is cumulative impact which would exceed a call-in threshold were it to have arisen from a single application, the Secretary of State will review the application. The document describes the decision-making process, but the technical considerations applied to assessment far outweigh the environmental considerations. As indicated in our general comments, Appendix G 7.1 on p193 is the nub of the decision-making process regarding noise impact, but simply says "Has the noise impact been adequately assessed". The CAA needs to consider how to achieve such "adequate assessment". Since the CAA itself has only recently resolved the issue of overflights (ref CAP 1498, Feb 2017) it is not exactly leading the field on environmental impact awareness. We regard it as vital to have an independent ICCAN, empowered, competent to oversee this crucial part of aviation decision-making going forwards, with the object of achieving noise reduction as an essential balance for aviation expansion, and with powers to require airspace change modification, or compensation, where this is not being achieved. Whilst we would endorse the proposal for Public Evidence Sessions, we request clarity re para 208 on what they are intended achieve as outcomes. The clue may be in the sub-bullet where the sponsor may be directed to clarify "what has changed between the consultation proposal and the formal proposal" - but is this an opportunity for the stakeholders to react? Otherwise what would the CAA be expecting stakeholders to say other than what they had already submitted? Is this for stakeholders who found the submission process too onerous and wanted to just attend and present their points verbally? When it says the CAA will be listening and asking questions, will the entire transcript taken into account and weighed in decision-making? This is cumbersome. PES is a valuable concept, but it looks a little "tacked on" and we request the purpose and objective is made more clear. For example, independent facilitation could enable it to focus on the key or most sensitive issues and to produce a summary of outcomes in relation to clarifying whether where and why there is agreement, compromise, disagreement or uncertainty in those key areas. This could then guide requests for further dialogue or further research (eg the production of a noise model) to illuminate decision-making and hence avoid the possibility of having to go around the loop again. It is not clear whether comments on Appendix G (the CAA's approach to interpreting policy, as referenced in para 203) are invited as part of this consultation. Ref para 230, we note as indicated earlier that sponsors can easily abuse the call-in process by "chunking" their major ACPs into major steps each of which just fall short of the call-in criteria. For example see Luton Airport's 2012/13 application to increase capacity by a declared 9 million passengers per annum (just short of the 10 million threshold for call-in) when the works being implemented would clearly and demonstrably permit a capacity increase of greater than 9 million, a point made by LADACAN at the time and which fell on deaf ears as far as the SoS was concerned. We note ref para 236 that a Judicial Review is an extremely expensive process and is just in relation to process and not outcomes: hence once the CAA has made its decision, communities effectively have no means to appeal even if the outcome is to degrade their quality of life. This again underlines that it is essential for ICCAN to play a part as an independent, empowered, point of appeal. Input from ICCAN needs to be folded into the complicated diagram on p67 - and at all other key stages where independent noise impact review is clearly necessary.

Para 247 suggests a lack of confidence in what should already be happening via the ACCs. Where the sponsor is an airport, to say "The change sponsor is expected to continue to engage with its stakeholders during this first year of implementation" implies that the sponsor may not already be doing this via its local ACC. We would request the CAA consider and advise government on whether it or the DfT should be responsible for ensuring that ACCs are engaging adequately with ACP sponsors, given that CAP1520 requires effective dialogue with stakeholders to take place.

We request that ICCAN or a third party should be required to perform an independent assessment, separate from the sponsor and on behalf of the CAA, of the noise and environmental impact benefits/disbenefits of the change as part of the PIR. The sponsor will (if an airport) clearly be primarily focused on its own objectives and cannot be expected to take a dispassionate view of the impacts, particularly if negative, on local communities. Stakeholders themselves are unlikely to be equipped for perform such assessments, since noise monitoring and analysis to rigorous standards will be required. The CAA is not resourced to do this either - reference LADACAN's request to the CAA when the adverse effects of Luton Airports R26 RNAV implementation became clear. On p214 it is not clear what is meant by "feedback that the change sponsor has received in the period since the change was implemented" in terms of data gathering. There is currently a lack of clarity as to what data and feedback will be gathered by a change sponsor under CAP725. We request it be made clear that as well as complaints data and track data, CAA will under CAP1520 expect the sponsor to pass on reports and other written feedback from communities and their representatives relevant to the PIR process.

In LADACAN's experience, a gap can exist between what a sponsor considers to be effective engagement, and what a community considers it to be. In order to gauge the effectiveness of consultation and engagement we request the CAA to engage with the district and county councils in areas affected, and the chairs of local ACCs, to seek their opinion by way of a statement or responses to a standard set of CAA-defined questions as to the effectiveness of local engagement.

The CAA should consider mandating the use of a third-party facilitator, funded by the sponsor up to a reasonable limit, to guide and assist any community and stakeholder engagement, particularly given the onerous nature of the CAP1520 process. A given sponsor may engage in the process only infrequently and cannot therefore be expected to have all the necessary expertise to hand either.

A facilitator would be useful in the assessment of whether the proposed outcomes of airspace change have been adequately researched and fairly presented in the local context. This is particularly relevant in stage 3 "consultation preparation", where fair expectation management on the part of the sponsor is an essential part of successful engagement. Facilitation is important where actual outcomes do not appear to match expectations, as part of the PIR process. We also propose facilitation/scrutiny of the process of response categorisation (see answer to next question).

Whilst categorisation may be of value, a careful respondent may have raised a number of points each of which may fall into a different category. The guidance does not make it entirely clear whether the whole response is to be categorised one way or the other, or the individual points. The latter approach is more useful, in which case the relevant points would need to be extracted carefully and fairly from the response. Please clarify. Interpreting the possible typo in table C2 "The content of this response will include not include new information..." as "The content of this response does not include new information..." we just query in whose judgement something is considered capable of impacting the proposal? The sponsor is asked to make this judgement, but clearly if a proposal is made which the sponsor for its own reasons is disinclined to agree with (for example because it may upset its airline customers) then the proposal may be set aside. This is another key point at which independent scrutiny may be required.

We would reiterate that the more that is agreed behind closed doors between the sponsor and the CAA, the less trust will be engendered. Stakeholders at least in the form of the local ACC should be involved wherever possible in order to seek to reach agreement on the top-level methodologies in a careful and reflective way (ie not by bouncing the stakeholders into quick decisions in the course of a single meeting). We request also, here or elsewhere, that options appraisal should take account of the need for baseline noise levels to be established in the to-be-affected locations before anything is changed.

It would be helpful if there were a standard template of criteria and issues which the CAA considers to be relevant to safety at airports, to which the sponsor has to respond, in order at least to start the process off. Certainly assessment should be made of any impact on the location and extent of Public Safety Zones, and corresponding locations of schools and hospitals, and this information should be available to stakeholders including local councils.

The distinction between Tier 1b and Tier 1c is perhaps over-emphasised, and the proposed process appears quite different. Para 274 states in relation to Tier 1b "The distinction from Tier 1c (operational trial) should be noted. Tier 1b is used for specific events or operating conditions that require a temporary change, whereas Tier 1c is used for an operational trial of innovative airspace design or of the use of new technologies." We are told that Tier 1b changes would last up to 90 days; however it is likely, given the need to gather statistically meaningful data over a period of different weather conditions bearing in mind E/W wind shifts, that a meaningful trial may last 2-3 months as well. So why is a Tier 1b change proposed to involve consultation and a Tier 1c change not? Surely they key here is not so much the (arbitrary) classification, but the likely noise impact and perception of change. If the impact is likely to be significant and noticeable on the ground, then consultation or at least very good information is required, less so if not - depending on the ultimate objective. In all cases the necessary rigour would be required to guarantee safety and good operating practice, which is taken as read. The decision about whether to consult or not could be taken at stage 1, with involvement of stakeholders.

See our response re Tier 1b

If the CAA is to venture into space then it might well be to the advantage of local communities to convert noisy airports into spaceports with only one or two flights a year...

We have answered on the assumption that the proposed impact will be to increase noise for those on the ground. CAA should view likely impact on people and their quality of life as a key decision criterion, given the significant expansion in aviation which has occurred over the past 10 years and continues to occur, unmitigated by correspondingly significant development in quieter and less polluting aircraft capable of zeroing out the impact of growth. A growing deficit is being facilitated, and CAA should consider also that aviation is the fastest-growing contributor to greenhouse gases. The CAA should demand the highest rigour in engagement and assessment of any proposals likely to increase that immediate burden, but we would support reasonable ways to streamline and fast-track the progress of proposals which are genuinely focused on reducing that burden. The way the question above is framed does not permit that distinction to be drawn.

If the government chooses to encourage and support unfettered growth in aviation, then it must take responsibility for reducing the carbon footprint overall, not just by focusing on the few miles during which flights most badly afflict people with noise near airports. The balance of weighting should be tilted towards minimising noise impact when closer to the ground, and minimising carbon footprint when higher up - for example by eliminating inefficient airspace usage particularly in the form of arrivals stacks which waste time, carbon, fuel and money; by designing efficient airspace interaction to avoid departing flights being held low; and by promoting in carbon-efficient noise-reducing engine technology. CAA should consider how its policies and process could positively discriminate in favour of proposals which first reduce low-level noise and second reduce resource wastage.

A possible loophole has been created by the way the criteria for Tier 3 are described. Table 4 on p86 states "Over time, as technology has improved, aircraft have become more able to operate along the centrelines of published departure routes. This can mean that swathes of departing aircraft become more concentrated over time along a centreline." It is clear that the introduction of PBN technology on a route will lead to significant concentration of flights - that is its purpose - and it is well known that where such technology is used in the context of routes which involve turns, the spread of flights under conventional navigation is likely to be much wider than under PBN, by a factor of 10 or 20. It is not acceptable that an airport operator has an apparent option to "transparently inform" stakeholders post-hoc about a PBN implementation. The change in noise profile between a widely dispersed swathe and a narrow RNP "motorway in the sky" is very substantial indeed. Witness the significant increase in complaints from residents around Gatwick and Luton airports in response to RNAV implementations. We request explicit clarification in CAP1520 that introducing PBN constitutes a Tier 1 change because it is a permanent and substantive step-change in airspace usage and noise impact. Stakeholders will want to be reassured that appropriate noise modelling and environmental impact assessment has been performed (including establishing adequate noise baselines), and that the 3D design of the route is going to deliver less noise on the ground (the really important issue) rather than just being a box-ticking exercise to show "less people overflown". Concentration is not necessarily always better, and a few extra track miles in order to reduce noise impact is likely to be seen as justified by those on the ground.

CAA should require airports to publish historic information which enables trends in key metrics such as numbers of flights, average spread of noise over noise bands and overall area beneath noise contours over the past 10 years to be easily viewed by the public and the regulator. It could form a mandatory part of Annual Monitoring reports, which otherwise tend to be isolated snapshots. On the basis of such trends, the CAA consider whether its regulatory role should include engaging with a local planning authority to review planning controls if the environmental impact of an airport has increased significantly over time without any airspace change proposal. If trust has broken down there is no evidence to suggest that the industry will self-regulate, in which case the CAA needs to clarify what its powers are in such circumstances.

The purpose of Airport Consultative Committees is in part to safeguard against such a lack of transparency. We request that the CAA calls attention to the important role of ACCs and promotes an annual effectiveness review to ensure that the guidelines for ACCs are being implemented effectively. CAA should also consider what provision it should make to provide for "appeal against a lack of transparency" should stakeholders not receive adequate or timely information from a sponsor. In other words, the CAA is proposes an ACP process which depends on these key consultative mechanisms, so the CAA must be satisfied that the mechanisms are in place, and must make clear how it will rectify that if they are not.

Such Tier 3 exploration may need independent facilitation and possibly last resort regulatory intervention. It is unacceptable for a creeping change such as increased size and noisiness of aircraft, increased numbers of flights, increased incursion onto sensitive times of day or night, material change in altitude, material change in departure procedure or any other factor causing a significant change over time of the environmental and noise impact to go unremarked and unregulated. If necessary, a requirement for mitigation or compensation should be imposed, and again the CAA should make clear its position on creeping change, the criteria which would trigger regulatory review, and the sanctions or remedies which would be imposed.