London city CTA

[mike172]

A quick question guys. Looking at my chart got me thinking, what is the point of the City CTA? It extends probably about a mile out from the CTR, why not get rid of it or just make it all a CTR?

Maybe I'm just being stupid, but I can't see the point of it, and I'm curious! Can any of you guys shed some light?

[ATCO Two]

A very good question indeed. The extension to the London City CTR was originally designed to add a extra 1 nautical mile to the North and South of the existing CTR, and 1.5nm to the East. This was to protect a greater variety of IFR traffic with different performance characteristics, since the original CTR was soley designed for the Dash 7, the only aircraft originally certified to operate into London City Airpiort. On hot days, departing aircraft were going outside CAS on the SIDs, and when vectoring for runway 10 (now 09 by the way),arriving aircraft had to be kept three miles away from traffic on the 10 ILS, which with a 4nm CTR either side of the centreline meant that they were right on the edge of CAS. When the plans for the new expanded CTR were put out to consultation as part of the Airspace Change Proposal, there were various objections from airspace users and other agencies. Therefore the ACP was "watered down" and the CTA was established around the existing CTR. To all intents and purposes the airspace beneath the CTA is more or less sterile, although we do notice some 7000 squawks sneaking under the Eastern edge at 1400ft!

[ThamesOperations]

As ATCO Two states, the CTA idea helped NATS overcome the objections from several agencies. We didn't want to narrow the "gap" between Stansted airspace in the vicinity of Stapleford, and we kept some unregulated airspace available to the north of Biggin Hill.

The CTA was also introduced at the same time as the change to the low flying rule (now 1000ft over....rather than 1500ft over highest point etc.), thus allowing light aircraft to legally fly below the CTA (as long as they can alight clear of the built up area).

It was a compromise between the ideal and the access issues, and in my experience, people have been able to take advantage of this unregulated airspace.

[mike172]

Thanks for the answers guys. Can't believe people would fly under the CTA though! Just a little bit off course and a man with a clipboard would be knocking on your door no doubt!

[MrHorgy]

I would, my house 200m from where the CTA extends to ground level - means I can buzz my folks without bothering Thames :ok:

Horgy