MP raises questions following airport consultation

17th December 2013
MP raises questions following airport consultation

Local MP Gordon Henderson has raised questions following the consultation exercise run by Southend Airport on controlled airspace. The questions and answers are as follows:-

1) Please confirm the location of “Choke Points” and whether these will be over the Isle of Sheppey:

“Choke Points” is a term widely used in the General Aviation (GA) community to describe a corridor of Class G (uncontrolled) airspace which lies between segments of controlled airspace. Many GA pilots have an aversion to operating within controlled airspace, notwithstanding that they are fully entitled to operate within Class D controlled airspace. They perceive themselves as being “forced” to remain within the corridors of uncontrolled airspace, thereby identifying an increased risk of encountering other aircraft. Naturally, with a terminal airspace environment as complex as that in the south-east of the UK, which serves the needs of 6 relatively closely spaced airports and numerous peripheral airports, it is inevitable that the controlled airspace configuration required to protect the Commercial Air Transport (CAT) flights from encountering uncontrolled GA flights will result in some corridors between adjacent Control Zones (CTR) (down to the surface) and Control Areas (CTA) (not down to the surface) at the lower levels. Conversely, by utilising Class D airspace, which permits operation of GA flights operating under Visual Flight Rules (VFR – “see and avoid”) within it, rather than Class A airspace, which does not permit VFR operations, a compromise is reached whereby all aircraft activities can be safely managed alongside each other.

The objective in airspace design in such a complex arena is to leave as much uncontrolled airspace as possible, within the safety constraints of protecting the flight paths of CAT flights to the extent required by the CAA and this we have endeavoured to do within the proposed controlled airspace configuration. Unfortunately, many pilots are unaware of the detail of these requirements and this leads to misconceptions as to basis of airspace designs.

With specific respect to the LSA proposal, as you will be aware, LSA is fairly close, in airspace terms, to London City Airport and the respective runways are not aligned with each other. Thus the space between the existing London City CTR and the proposed Southend CTR is approximately 8½ nautical miles (NM) at the surface and approximately 7 NM wide from 1500ft to 2500ft above the surface. This is perceived by the GA community as a Choke Point, but is not near the Isle of Sheppey.

Moving to the Isle of Grain, the proposed Southend CTR extends across the Isle of Grain, encompassing Cliffe and Kingsnorth. Rochester Airport has an Aerodrome Traffic Zone (ATZ) of 2NM radius around the Airport and which extends vertically to 2000ft above the Airport. The gap between the proposed Southend CTR and the Rochester ATZ is approximately 3NM. In our proposed airspace design we have also “cut back” the proposed Southend CTA-2 (which extends from 1500ft to 3500ft above the surface) to increase the space between the Southend CTA and the Rochester ATZ and to allow microlight operations from Stoke aerodrome to continue to be facilitated. Southend ATC has a good operational working relationship with Rochester Airport and this will be developed further to ensure the effective integration of Rochester traffic with LSA traffic.

Specifically over the Isle of Sheppey, the new proposed controlled airspace is CTA-4 which extends from 2500ft to 3500ft above the surface and abuts the existing London Terminal Control Area (LTMA) at 3500ft. There are no perceived “Choke Points” between this segment of controlled airspace and any other controlled airspace. Unfortunately, the GA perception is, erroneously, that GA aircraft will be “forced” to fly 1000ft lower than they currently can. In fact GA VFR flights can be given ATC clearance to operate within CTA-4. CTA-4 is necessary mainly to protect CAT flights departing from LSA to the south as they climb into the LTMA above. Due to the complexity of other air traffic and routes from 4000ft upwards, London Terminal Control (LTC) cannot allocate a level above 3000ft (as a procedural ‘fail-safe’) to Southend departing traffic until it is in direct communication with them. CTA-4 will also protect arriving aircraft inbound to runway 06 from the south-east as they descend towards their final approach.

2) I already receive complaints from Islanders about the number and height of airliners flying over Sheppey, please confirm that these proposals will not lead to a further increase in commercial air traffic.

The aircraft overflying the Isle of Sheppey comprise departing aircraft from both London City Airport and LSA and some arriving flights to LSA. Because of the complex airspace arrangements in the area of Detling (which is a main exit route for Heathrow and Gatwick departures to the east) departing traffic from London City and Southend is routed through a corridor known as the “Thames Gate” which encompasses the Isle of Sheppey. The Thames Gate arrangement allows LTC to climb traffic earlier than would be the case if it routed via Detling. The London City departing flights will always be well above 4000ft over Sheppey. Southend departing flights will generally be above 3000ft, although the initial cleared level is limited to 3000ft as detailed above. However, once 2-way communication is established with LTC the 3,000ft ‘restriction’ is removed and radar separation provided. It is important to note that to the LSA airspace proposal only envelopes existing routes and procedures and does NOT allow aircraft to fly lower for longer; the operational effect will be quite the contrary.

With respect to increased commercial flights, as you are aware, commercial air traffic is now growing again at all airports and LSA anticipates gaining its share of that growth. However, the proposed development of controlled airspace is not a facilitator of growth. As part of the planning permission for the runway extension back in 2010, LSA complies with a number of conditions under a Section 106 Agreement. One of these includes a cap on the number of movements LSA can handle per year.

3) What will happen to the non-radio and non-transponder equipped light aircraft that currently use Southend Airport?

There are very few non-radio aircraft that wish to use LSA but those that do are accommodated on a “prior arrangement” basis. The same is true of non-radio access to the proposed controlled airspace. For the smaller aerodromes that will be encompassed within the proposed controlled airspace, and which have non-radio aircraft based there, we anticipate developing Letters of Agreement to enable their continued routine operation. This is common and standard practice for this type of airspace.

Carriage of a transponder is not a requirement for flight in Class D controlled airspace and Southend ATC will continue to accommodate non-transponder aircraft as they do now.