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-   -   Decca 424 Airfield Radar (http://www.pprune.org/atc-issues/476630-decca-424-airfield-radar.html)

Mooncrest 8th Feb 2012 10:26

Decca 424 Airfield Radar
 
The previous thread from some years ago is closed so apologies for this...

Is anybody out there still using one of these ? Doubtful, I know, given the vintage technology. I ask because I've recently seen a picture of Leeds Bradford Airport circa 1965 and I can just make out the distinctive shape of a 424 radar head lurking behind a BKS HS748 (it is that old) ! It intrigued me because I thought LBA's first radar was a Plessey ACR430. Obviously not.
We now have a Watchman and that's well over twenty years old itself.

Speaking of the Watchman, is this radar still in use at Manchester (or any other NATS airports for that matter) ? It's difficult to tell from the car park roof if I'm looking at a Watchman or a Raytheon thingummyjig.

Thankyou all :ok: .

spekesoftly 8th Feb 2012 11:24

Quote:

Is anybody out there still using one of these ? Doubtful, I know ....
Hawarden might have been one of the last UK airfields to use the 424?

Liverpool's 424 was replaced in about 1982 with an ACR430. (Subsequently replaced by an S511 and now ASR10)

"Tilt Up" ;)

HEATHROW DIRECTOR 8th Feb 2012 11:42

I believe some of my ex-colleagues are still using one at Lasham....??

Buster the Bear 8th Feb 2012 13:16

LL Dir, I think that you are correct?

MNT 8th Feb 2012 19:16

Watchman.
 
Manchester is still using a Watchman but should be replaced in about 12 months time, only NATS site left not sure about anybody else.

Tigersaw 8th Feb 2012 19:35

Southampton still using a Watchman, and plenty of life left in it

chevvron 8th Feb 2012 19:47

424 still in use at Lasham, the 430 being a development of it using a cosecant squared reflector rather than the original pencil beam which in turn (so I'm told) was originally designed as a marine radar.
Try 'Talkdownman' for more details.

Sir George Cayley 8th Feb 2012 22:45

Will Lasham's be affected by the OFCOM frequency band sell off? Something about mods needed to carry on.

SGC

Talkdownman 9th Feb 2012 09:14

Quote:

Originally Posted by Sir George Cayley
Will Lasham's be affected by the OFCOM frequency band sell off? Something about mods needed to carry on

News to me. It's still turning, and still burning...as long as there is a good supply of Ford Anglia fan-belts...

Quote:

Originally Posted by chevron
was originally designed as a marine radar

She's off an early fifties frigate. Spares available at the Science Museum apparently...theirs is younger...there's only about three blokes remaining who know how to fix it...there's certainly only three blokes remaining who know how to use it....

tweentown 9th Feb 2012 09:52

The 424 that was used at EMA is on display in the aeropark museum there - visible in google maps satellite view.

Talkdownman 9th Feb 2012 09:59

Ah, more spares.....

Mooncrest 9th Feb 2012 15:37

Good to see the old 424 is still hanging on by a thread, but I confess I didn't know Lasham even used radar. But that's another story...

Always to encouraging to know that old(er) ATC equipment is still being used, even in the ATC powerhouse that is the UK. It makes me wonder how much longer our (EGNM) Watchman will be in use before it has to make way for a more modern system. I suppose as long as it does the job and spares are available and economical. The old PO lever key switch panels and Racal headsets gave way some years ago to fancy touchscreens and flimsy Plantronics stuff.

I gather the 424 was something of an acquired taste in terms of usage and maintenance :\.

HEATHROW DIRECTOR 9th Feb 2012 16:33

I still reckon the Heathrow ACRVI was better than all the modern digitised stuff.... but then I'm grossly old-fashioned!

Wonder what happened to that ancient clockwork Echo arrangement at EGMC?

welkyboy 9th Feb 2012 16:39

You mean the EKCO ARAA. Spent a lot of time under the curtain talking Carvairs etc . Down to half mile on 24/06 very accurate though care was needed in setting it up after a runway change!!

Talkdownman 9th Feb 2012 18:25

We had an ARAA at Elstree mid sixties. Never saw it working. Rain came through the necessary hole in the roof...
There was also one at Lasham early seventies. Might have been Sahfend's reject. I understand the trick at Sahfend was to take down the controller's trousers mid-SRA...

chevvron 10th Feb 2012 00:45

The Lasham 'Eckoscope' was the original sarfend one. A guy called Arthur Beaton was the controller there originally (c'74 - 78), however I heard a rumour he wasn't licenced. After him, Des Middleton took on the task and that's when the 424 replaced the ARAA

Helen49 10th Feb 2012 07:05

The first radar installation at Leeds Bradford Airport was an Ecko ARAA. It was replaced by the Decca 424 [originally designed and used as a marine radar] c1963/64.

The 424 [later became Plessey 424] was a splendid piece of engineering but with only a 3cm wavelength worked superbly as a weather radar not quite as superb for seeing aircraft during heavy weather! The 424 with its various devices for removing weather clutter and a tilting aerial [the ATCO needed two pairs of hands at times!] had a maximum range of 25 miles and also had a one mile range setting enabling it to see airfield movement activities although, of course, not approved for that purpose.

The Plessey 430 arrived at Leeds Bradford early to mid 70s. This provided better vertical coverage [as opposed to the single narrow beam of tthe 424] but again being 3cm wavelength was often badly affected by weather clutter. Later modifications to the 430 made significant improvement but not until the arrival of the Plessey Watchman was the weather clutter problem resolved for LBA.

With the LBA standard weather [cloudbase below the top of Murgatroyd's chimney, itself later replaced by a fish and chip restaurant!], SRAs to half a mile were the most important approach aid. SRAs were 'the norm' to Rwy 15/33 and 10/28. Of course the advent of the Watchman meant that LBA no longer had the half mile talkdown capability but did, by that time, have an ILS on both ends of the main runway. SRAs to half a mile had continued to be available on Rwy 28 until the Watchman arrived.

Those were the days!

H49

chevvron 10th Feb 2012 10:35

The Watchman installed at Farnborough was MOD owned hence it had permanent touchdown markers in the form of MTI markers ie battery driven devices which 'broke through' the MTI, so we could (if approved) have done 1/2 mile SRA's, but we also had a CR62 (3cm precision approach radar) so this wasn't necessary as you could do 1/2 mile 'no glidepath' talkdowns on the CR62 instead.

Talkdownman 10th Feb 2012 11:04

Quote:

Originally Posted by Helen49
The 424 [later became Plessey 424] was a splendid piece of engineering but with only a 3cm wavelength worked superbly as a weather radar not quite as superb for seeing aircraft during heavy weather! The 424 with its various devices for removing weather clutter and a tilting aerial [the ATCO needed two pairs of hands at times!] had a maximum range of 25 miles and also had a one mile range setting enabling it to see airfield movement activities although, of course, not approved for that purpose.

Still is, still does, still do, still has, still isn't. And all with classic tangential fade...
If it hadn't been for John Townsend I would never have understood such a radar...

Loki 10th Feb 2012 11:09

You're all talking nonsense.....Marconi 264 for me (so good, we had 2 of them at EGPF)


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