Remote SSR feeds for airport approach control

[Mooncrest]

At airports which don't have their own SSR head but buy in coverage from a remote site or sites, would it be possible and/or desirable for the radar display to simultaneously show data from more than one site ? For example, Leeds Bradford Airport has, for many years, used the NATS site at Claxby as its preferred SSR provider, with Great Dun Fell as a back up. Would it be technically or theoretically possible for both to be used at once to provide improved overall coverage ? There could well be a cost implication but I wondered if multiple site coverage would otherwise be advantageous.

Thankyou.

[Roger That]

If you’re buying a service, you may simply specify the service your want and the performance you are contracting to ....how your service provider provides it may be immaterial so long as you can rely on it for the performance you specify, and in turn the services you use it to provide.

[chevvron]

I think it's done in France but the CAA frown on it.
It should be possible by feeding different SSR plots into a computer and choosing the 'best' one but this will not necessarily show the SSR plot in a position accurate enough for use in vectoring aircraft in an instrument pattern and could show extensive track jitter.

[Mooncrest]

Thankyou both. I honestly didnt know the practical or technical ins and outs of what I was thinking. However, from the point of view of LBA, Great Dun Fell could provide improved SSR coverage in the high ground to the north and west of the airport, whereas Claxby would be better suited to cover areas to the south of LBA. That said, there are several ATC radar units in said area (Doncaster, Humberside, East Midlands and Manchester) already.

[topdrop]

Depends on the software that your radar data is fed into. Many places have multiple radar feeds to one display to cater for terrain issues. Have 3 feeds where I work. To merge the feeds, the display is chopped up into small squares. Each square has a percentage bias for each radar and displays the composite result. As aircraft close to each other are processed using the same or similar bias, any error applies equally to both aircraft.

[chevvron]

Thankyou both. I honestly didnt know the practical or technical ins and outs of what I was thinking. However, from the point of view of LBA, Great Dun Fell could provide improved SSR coverage in the high ground to the north and west of the airport, whereas Claxby would be better suited to cover areas to the south of LBA. That said, there are several ATC radar units in said area (Doncaster, Humberside, East Midlands and Manchester) already.
I don't think any of those 4 airfields have their own interrogator apart from perhaps Manchester.
At Farnborough, each of the 3 LARS sectors has 2 radar displays and can potentially access 5 different radar feeds one at a time both primary and secondary. We wanted to 'mosaic' different feeds onto the same display but for various reasons, the CAA would not approve it.

[Mooncrest]

It will be interesting to see what equipment LBA selects when the time finally comes to replace the Watchman primary. The processing equipment was upgraded about three years ago with 4G-proofing done before that so this may not be any time soon. The Watchman has proved to have considerable longevity at LBA - been in service for just shy of thirty years and has long outlived its ACR430 predecessor. I wonder if LBA will this time buy their own SSR aerial or continue the supply arrangement with NATS.

[Mooncrest]

Thankyou, Looking, that's an interesting angle. I'm sure I've read before about how multiple SSR interrogators can create problems. I guess in the UK, either the CAA or OFCOM get to decide which units can have their own SSR and which can't. Using the system to track ground movements would be advantageous for LBA, given its infamous weather and current lack of ASMI.

[chevvron]

The RAF have interrrogators at some airfields in addition ot those operated by NATS.