National Air Traffic Service

NATIONAL AIR TRAFFIC SERVICE TERMINAL CONTROL NORTH PROPOSED CHANGES TO AIRSPACE CONSULTATION FEBRUARY 2008 – BRIEFING NOTE

Overview of the TCN Proposal 1. Improved Safety and Reduced Delays – Safety is NATS’ highest priority. It is always seeking ways to make the airspace under its control even safer and it considers the proposal will, if implemented, reduce the complexity of the TCN airspace, which will mean an improved level of safety for each flight through the region.

2. Converging Departure Routes - A number of departure routes from Heathrow, Stansted, Luton, London City and Northolt airports converge over Bookman’s Park in south Hertfordshire. The TCN proposal will spread these routes more effectively and disperse aircraft over a wider area than today. NATS considers reducing congestion in this way will cut delays and improve safety.

3. Shared Holds for Luton and Stansted – Luton and Stansted currently share ‘holds’, where aircraft fly a prescribed circuit waiting to land (holds are also sometimes deferred to as ‘stacks’). Sharing holds causes additional delay because traffic for one airport can get stuck behind traffic queuing for the other. The proposal will provide separate holds for Luton and Stansted traffic to alleviate this additional delay.

4. Increasing Traffic Levels Inbound to Stansted – Traffic at Stansted has been growing and NATS expects growth to continue. This continued growth will mean that during busy periods, Stansted will require two holds. This proposal, therefore, provides an additional hold for Stansted arrivals.

5. Arrival Routes for London City, Luton and Stansted – Arriving aircraft flying from holds to these three airports do not currently follow a set route. The proposal includes establishing set routes from the holds to the runway, although air traffic controllers will still regularly need to take aircraft off the set routes to maintain safety and efficiency. Where possible the set routes will also be centred away from population centres, which will help reduce over flight of people’s homes at lowest levels.

6. The set arrival routes for Luton and Stansted will also enable continuous descent approaches (CDA’s) to these runways. These approaches can reduce the noise experienced by some of the populations overflown and reduce the overall aircraft emissions during descent.

7. Improved Aircraft Navigation - The existing airspace structure is based on the use of ‘conventional navigation’, where aircraft use ground-based navigation beacons to determine their position during flight.

8. Modern navigation technology called ‘Precision Area Navigation’ (or P-RNAV) is now available and NATS is required by the Civil Aviation Authority (CAA) to apply it to all new route design. P-RNAV does not always require aircraft to fly over beacons. It will enable aircraft to fly more accurately along a given route which, in line with Government guidance, will concentrate air traffic in some areas, limiting the geographical speed of aircraft tracks and their associated impact on local communities. The introduction of P-RNAV will assist in addressing the safety, capacity and environmental issues that exist in the TCN region.

9. Improved Environmental Performance – NATS says it recognises the potential impact of aviation on the environment, and when proposing an airspace change, includes environmental aims, such as minimising the population overflown at low levels and seeking to reduce fuel burn/emissions.

10. NATS’ analysis has shown that the nature of the change in the TCN proposal do not impact local air quality.

11. In designing airspace, the environmental objectives relating to noise and fuel/emissions efficiency are often at odds. For example a shorter route that burns less fuel may take aircraft over a town. 12. NATS has determined a rationale that means routes below 4000ft have been positioned to avoid over flying sizable population centres. Between 4000ft and 7000ft, it has been necessary to balance the requirements of mitigating noise and reducing fuel burn and emissions.

13. When designing airspace below 7000ft, it is not possible for routes to avoid all villages, towns and cities. However, NATS, says it works hard to avoid as many as possible, taking into account the competing aims of ensuring safety, reducing delay and mitigating environmental impact. The larger the village, town or city the more benefit (in terns of population overflown) there is in avoiding overflight at low level. Even so, on occasions avoiding one area means another will be overflown.

14. Changing Routes and Airspace Definitions – The TCN proposal, if implemented, will mean a number of routes being realigned so that aircraft fly over different areas than they do today. A number of other routes through the region will not change, most notably Heathrow arrivals and Stansted departures to the east and southeast. (See paragraph 4.10 of main report for further details).

Population Counts Beneath Noise Preferential Routes 15. Government guidance states that airspace changes in the vicinity of airports should aim to ‘introduce modified routes that over fly as few people as possible’.

Population count analyses have therefore been performed on various elements of the design in the vicinity of airports to test the development against this objective.

16. Noise Preferential Routes – For most major airports in the UK, aircraft following a departure route 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 3km wide within which the aircraft may be seen and heard under normal circumstances. This swathe is the ’noise preferential route’ (NPR). The altitude below which aircraft must stay within the NPR is either 3000ft or 4000ft, depending on the route in question. 17. The NPRs would change as a result of the proposed P-RNAV routes. Analysis was therefore undertaken to compare the number of people beneath the existing NPRs and those for the proposed P-RNAV route.

18. A summary of the population counts for NPR’s at each airport is provided in the table below:

Population counts for Noise Preferential Routes (up to 4000ft) Londo Stansted Heathrow Luton Northholt* Total n City* Current 858429 11824 460848 64133 206679 1601913 Design Proposed 558576 3891 421567 53395 237933 1275362 Design % -34.9% -67.1% -8.5% - 15.1% -20.4% Difference 16.7% * note that NPR’s do not currently exist at London City or Northolt but they have been assumed here for the purposes of comparison.

These figures, however, mask the fact that some people will continue to be overflown, some will not now be overflown and some will be overflown for the first time.

19. TCN airspace is used by many aircraft arriving and departing from airports in the London area. Aircraft from the London area heading east and north-east generally fly through the East Herts and West Essex Area. All aircraft arriving and departing from Stansted Airport use the airspace and it is also used by aircraft over flying the TCN region at a range of heights above 8000ft.

20. There are a number of air traffic flows passing over East Herts that NATS is not proposing to change as part of this proposal:-

 Gatwick departures  Stansted departures to the south east and east  Heathrow and Northolt arrivals  Arrivals and departures to smaller airfields in the London area  Overflights from other UK airports going to, or heading from Europe and the Americas. 21. Air traffic flows over East Herts that would change as part of this proposal are:

 Stansted departures to the north and south west  London City departures  Luton and Notholt departures  Luton arrivals  Heathrow departures to the north east

22. Route and Flight Path Maps - The map and noise information in the NATS Consultation Document show the areas aircraft are expected to fly, their heights, the potential noise generated by each flight and the frequency of flight.

23. The heights shown on the route and flight path maps have been defined using conservative assumptions, which mean they represent the lowest an aircraft would be expected to be on that route; most aircraft on the route would be higher in reality.

24. Holds and Queuing for Stansted and Luton Arrivals – Stansted and Luton currently share two holds. The ‘LOREL’ hold is located in the vicinity of Royston and the ‘ABBOT’ hold in the vicinity of Sudbury, Suffolk. The proposal includes changes that will remove both holds and replace them with new holds further north in Cambridgeshire and Suffolk.

25. Changing the location of the holds will mean that the flight paths many arrivals take to the airport will change.

26. Changes to Stansted Departures to the North and West – The proposal includes changes to the departure routes from Stansted to the north and from both ends of the Stansted runway (easterly and westerly). Stansted departures from either end of the runway to the south and east will not change under this proposal.

27. Continuous Descent Approaches (CDA’s) - Continuous Descent Approaches reduce noise impact and improve fuel efficiency (thereby reducing emissions) by keeping aircraft higher for longer. 28. Arrivals to Stansted’s easterly end of the runway (also sometimes called runway zero five) are currently subject to an air traffic restriction that means they must descend early to 3000ft to enable Heathrow and Luton aircraft to pass safely overhead. This increases the noise impact on towns such as Ware and Hertford. The new design lifts this restriction, which means aircraft will descend later and can follows a continuous descent profile. Aircraft would therefore be between 1000ft and 2000ft higher over Ware and Hertford than they are currently.

29. Use of Direct Flight Paths – In terms of noise impact, a direct flight path will not specifically avoid over flying densely populated areas, whereas the proposed P-RNAV routes, between the hold and the runway, will avoid densely populated areas where possible. Therefore, noise from aircraft on direct flight paths is dispersed across the community, rather than concentrated over the generally less populated areas beneath the proposed P-RNAV arrival route. The wider community would, therefore, benefit if aircraft arriving in off-peak periods were to use the proposed P- RNAV route instead of using direct flight paths.

30. This proposal has the option to implement either method of arrival during less busy periods, i.e. air traffic controllers can position aircraft on direct flight paths from a number of directions or concentrate them on flight paths close to the published P-RNAV route.

31. Departure Routes and Population Counts – NATS states that minimising the number of people overflown by departure routes, where aircraft are flying a Noise Preferential Route (NPR) below 4000 ft, has been one of the objectives of the proposal.

32. NATS has undertaken an assessment of the population beneath both present day and proposed P-RNAV departures routes. The total population beneath the proposed Stansted NPR’s up to 4000 ft was found to be 8000 (67%) less than under the equivalent present day NPR’s. These total figures, however, mask the fact that some people will continue to be overflown, some will not now be overflown, and some will be overflown for the first time.

33. Stansted Easterly Arrivals – Arrivals to the easterly runway at Stansted (the zero – five runway) currently fly in a wide swathe over Ware. Various options were tested during the design stage relating to this area. The aims were to minimise populations under the centre-line of the route and implement CDAs.

34. NATS state that whilst aligning the route over Ware is optimal in air traffic terms, it is recognised as not optimal in noise impact terms. Turning inside Ware and Hertford was considered, but this is not possible because it does not allow enough time for aircraft to descend to join the final approach at the appropriate level.

35. The proposed route alignment turns outside Ware and Hertford. An initial favoured option enabling CDA was centred over Hertford and Hoddesdon. However, as a result of earlier stakeholder engagement with local authorities, this option was considered unacceptable. Whilst not quite technically a CDA route, NATS believes that placing the centre-line to avoid Hertford and Ware, is preferable in terms of environmental impact, to a CDA compliant centre-line that goes over the towns.

36. NATS point out that aircraft do not always follow the route centre-line. However, moving the centre-line of the route away from densely populated areas is expected to reduce the proportion of aircraft overlying them. When aircraft fly over Hertford and Ware, the lifting of restrictions that force aircraft to descend early in current airspace, will mean they can follow a CDA profile and will be higher than they are at present.