Plessey Radar Display - Where did it come from ?

[10W]

The National Museum of Scotland's Museum of Flight at East Fortune were given an old Plessey radar display several years ago and they are trying to find out a little bit about its history and at what ATC unit it was used.

There is a rumour that it may have been used at some point at West Drayton before being transferred to an airfield somewhere in the UK. Apart from the display and its cabinet, the only other clues are probably in the burnt phosphor marks on the screen which show a cross runway configuration and various other marks which may be airspace and airfields.

If you recognise this piece of kit or where it might have been used, please let me know !!

[Sir Herbert Gussett]

... Heathrow? Is this some sort of in-joke I'm yet to get!

[10W]

Heathrow is the initial thought. But why two approach vectoring lines for RW23/05 ?

[Spitoon]

Re-alignment/re-positioning of the video map and radar data to extend the life of the tube? The east/west runways would presumably have been exclusively ILS approaches by this time and so it would matter less if the centrelines burned out. But I think 05/23 had SRAs until very late in their operational lives and so being able to see the target as it goes down the extended cenreline would be important - keeping this facility for longer could be achieved by shifting everything E or W slightly. I seem to recall this happening at places I worked when using similar (if not the same) bits of kit.

[Talkdownman]

That is/was the Heathrow Approach radar video map depicting east/west parallels, 23/05 and Northolt 25/07 (which is offset). The 23/05 'parallels look like PPI 'shift' burns on the phosphor. (I think I have similar burns on my retinae....). The crosses are NDBs and the squares are the minor aerodromes. The kit is a couple of decades too late for 23L and 23R! I would put that tube at about '89 when the CTB ground floor approach room was opened. I seem to recall that they were replaced with flat Sony Eriksson displays which then became redundant in '93 when Heathrow approach moved to West Drayton. (A four-year life for a very expensive expensive approach control facility...!) On the other hand that tube might be from the Training section sim. Hazy memories now.

Any comment from 'Heathrow Director'?

[chevvron]

The double centreline for 05/23 could be due to a shadow caused by using a 'map overlay' rather than an electronic video map, an overlay being a permanently etched transparent plate attached temporarily or permanently to the face of the display and used for SRAs. Judging by the nuts and bolts visible, this one was meant to be permanent. The airspace structure south west of Heathrow dates it as 1982 or later.
This looks like a 16" tube; we had clip-on ones at Farnborough on our old AR1 displays with 12" tubes with SRA lines for Farnborough, Odiham, Blackbushe and Dunsfold.
One pitfall you had to watch out for was making sure you had the correct range selected when using the overlay; I can remember one senior controller at Farnborough (Ken Spratt) trying to do an SRA one day. You needed to select a 7.5nm range. He sat there, looked at the tube and said 'there's no f....ing primary' until someone reached over and pointed out he had selected 75nm!

[10W]

Thanks all. That's great information, which I shall pass on.

[chevvron]

If it is an overlay, and I've no doubt it is, it would be intriguing to find out why Heathrow used such a 'crude' system when they had electronic mapping facilities.

[HEATHROW DIRECTOR]

I believe that when I started at Heathrow (Jan '72) the maps were produced by some sort of scanning device and the maps were etched on to glass slides. This accounted for the ease which Tels were able to display Christmas trees on the radars on 25 Dec!

[vapourer]

Perhaps the old memory is playing tricks but I seem to recall that when we switched the display from the 264 radar to whichever 10cm radar we had at the time and back again the whole video map moved because the radars were some distance from each other. The effect shown on that PPI might be phosphor burns from both video map positions. On the other hand that could be complete nonsense.

[2 sheds]

I believe that when I started at Heathrow (Jan '72) the maps were produced by some sort of scanning device and the maps were etched on to glass slides. This accounted for the ease which Tels were able to display Christmas trees on the radars on 25 Dec!

The maps were drawn in fairly large scale with a fine draughting pen, black ink on white cartridge, which was then photographed. The resultant negative transparency (about 3" square if I remember rightly, but stand to be corrected) was then inserted in a glass mount, rather like an old-fashioned magic lantern slide, through which a trace on a separate CRT illuminated it in synchronisation with the revolving trace of the radar display. Which is why when the displayed scale was expanded, the map information became somewhat fuzzy and even kinked as the film distorted. However, the ACR430 did not even have this luxury - see separate thread.

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