Epsom NDB - did it move?
 

I've joined this site just to ask this one question!
In about 1972 I listened to a conversation between two British radio amateurs discussing the Epsom NDB (EPM). Living in the area I already knew that EPM is actually a few miles away in Stoke D'Abernon. One of the guys was saying that the beacon had originally been in Epsom itself but had been relocated. I can't find anything on the web to support this. Can anyone confirm please and if it was relocated, when, and whereabouts in Epsom was it originally located? I have read that aircraft once circled over Epsom Downs to hold. Is this perhaps the answer?

The location of the Epsom NDB 'EPM' (freq 316 kHz) is the same today as it was in 1969 (chart shown below), approx 5 statute miles WSW of the centre of Epsom town, but I don't know its history prior to that. EPM is the holding pattern for aircraft to proceed to after missed approaches from LHR runway 09R/27L.

ILS chart R27L

I think one edition of the CAA charts might have "moved" it by mistake, along with the Princes Risborough mast, which suddenly appeared near Banstead!

My 1991 Pooley's has it in a slightly different position at 5119.13N 00022.22W. This might be due to a change in grid from OSGB36 to WGS84.

EPM is also a waypoint on the westerly Detling SIDs.

The NDB is at the far end of Blue Bell Lane, just past the Shetland Pony Club. :O

https://cimg2.ibsrv.net/gimg/pprune....fbbb919010.jpg

Was the Iberia Caravelle crash near Fernhurst on Blackdown Hill in Nov 1967 using that NDB for it's let down and APP from Malaga to LHR?

Sadly killed in the accident were British film and TV actress June Thorburn, who was five months pregnant. Other notables who died were industrialist and Coventry City Football Club vice-president John Clarkson, and Donald "Doc" Campbell of the Campbell Aircraft Company.

Just got this off the report - Iberia flight IB062 left Málaga, Spain, at 19:30 UTC on a flight to London-Heathrow Airport, United Kingdom. The local arrival weather at the time was slightly misty with intermittent drizzle but there was reasonable visibility.
The aircraft was cleared to descend to FL210 after passing latitude 50 °N and was given a routeing via Ibsley and Dunsfold. After passing conflicting traffic, the aircraft was recleared to FL110 and directed to turn right on to 060° for Dunsfold.
Passing abeam Fawley the aircraft was further cleared to FL60 and, in acknowledging this instruction, the crew reported leaving FL145. Just under 4 minutes later the aircraft was cleared to proceed direct to Epsom on its own navigation.
The flight crew acknowledged this instruction. All the while the aircraft had been in a continuous descent, until it impacted trees on the southern slope of Blackdown Hill, approximately 48 km south-southwest of Heathrow Airport.

Clearly popular for target practice. :O

https://cimg7.ibsrv.net/gimg/pprune....18515f9397.jpg

UK Navaids Gallery - Epsom EPM NDB (trevord.com)

Somebody with an air-rifle seems to have a dislike for the EPM NDB!?

I vaguely recall it was moved to its present position sometime after 1980 having neen notified as 'withdrawn' for a short time. At one time the coding was 'EPS' not EPM' and I suspect (stand to be corrected) may have been changed when it moved.
The co-ordinates quoted above seem to be OSGB 36 notation and not WGS 84 but I'm sure that change didn't happen until late '90s.

Those Pooley's coordinates point to the middle of the field next to the pony club, about 150 yards from the actual position of the antenna.

That amount of offset is the right order of magnitude for the different between the WGS84 and OSGB36 datums, as I recall from writing a routine about 20 years ago to convert between the two.

As to whether the NDB has been moved from a previous position, there may be some truth in that - despite the name, its current location is actually closer to Leatherhead than Epsom, but it may not have been in the past. More research required !

The present NDB is situated about half a mile north east of Chelsea FC training grounds which during WW2, were evaluated (but as far as I know not used) for use as an ELG or 'Emergency Landing Ground'.

The mast marked on the OS map above also appears on the 1960 edition but I suspect that, in both cases, this is the much larger telecoms mast that sits next to the NDB.

Flap40,

Thanks for that. I was looking at GE and thinking “That’s a really big NDB mast!”

I had no idea what an NDB looked like (I'm familiar with the VORs at Biggin, Seaford and - slightly bizarrely - Lands End...) so assumed the mast visible on Google was it. Bit of Googling shows me an NDB mast is slightly less substantial.

It was 'EPM' on this 1968 approach plate: https://www.vc10.net/History/Images/...B28L_epsom.jpg

http://www.trevord.com/navaids/naimages/epm1.jpg
The NDB is the smaller mast.

The Epsom nav facility also included one of the four 4-leg MF radio ranges serving the London area, the others being Watford, Dunsfold and Chatham (chart below). These MF ranges were withdrawn late 50s or early 60s. Garston VOR moved to Bovingdon but for a while retained its freq: 112.3 MHz.


https://cimg4.ibsrv.net/gimg/pprune....7ae476ff95.jpg

Some digging...

I've used this chart from 1960ish at https://atchistory.wordpress.com/202...ow-atc-part-2/ and also taken the variation of 7w as given on the Jepp chart.

https://atchistory.files.wordpress.c...-departure.jpg

Plotting a three way fix from Brookmans park, Woodley and Rochester (and assuming none of those moved before 1991) gives a fairly wide spread but the general consensus seems to be somewhere about 3nm ENE of the current site.

Google earth clip below with the three plots in yellow and the current position in green.


https://cimg4.ibsrv.net/gimg/pprune....943b6a88fb.png

Just found this...

https://hansard.parliament.uk/Lords/...ysRadioBeacons

@ Flap40: variation 7° would date the chart to late 60s or early 70s. From the UK Air Pilot COM section, page date 21/11/69. Note that the format for longitude omits the leading zero:

https://cimg1.ibsrv.net/gimg/pprune....0d3ec0f93c.jpg

I've just spotted Epsom hiding at the bottom of this...

https://atchistory.files.wordpress.c...app-rw28rl.jpg

Taking the LAT/LONG off that as 51.20N 000.17W puts it just east of my previous plots (pink pin) so I think we can safely say it has moved.


https://cimg3.ibsrv.net/gimg/pprune....b3bbdec5d9.png

As to when it moved, I think we can assume that it was in its original position when Lord Trefgarne asked his question in Feb 1968 and the co-ordinates provided by Discorde from Nov 1969 has it in the current position (allowing for datum change) so sometime in that window.

Good detective work! If the Jepp chart is correct then we can say that EPM moved a mile or two westward sometime between March '66 and November '69.

I've just found an old AIP that shows Epsom at N 51° 21' W 000° 17', so a little further north than your pink pin.

Bearing in mind those coordinates are to the nearest minute, the potential error is up to +/- 3000 feet N-S and 1900 feet E-W, and then you need to offset the bounding box by around 400 feet to account for the OSGB36 to WGS84 offset.

But it's definitely in a different place from its current location. :O

Since there has been mention of radio ranges, I thought I would look for a picture of the antenna layout. I could only find one picture - an anonymous US one:


https://cimg7.ibsrv.net/gimg/pprune....38b01b92f.jpeg

There were still some operational ones in Canada in the early 70s.

Dave can you confirm those co-ords please, I was just using Bing's Ordinance Survey map to pinpoint where it would have been sited and that places it in South Earlswood, just west of Redhill Aerodrome and about 10 miles SSE: 51.209683, -0.170325... :confused:

We're talking different languages. :O

My coordinates from the AIP are degrees and minutes, yours are degrees and decimal degrees. So N 51° 21' would equate to 51.35 degrees, for example.

As it happens, I've just been playing around with a conversion from OSGB lat/lon to OS Grid, and produced this bounding box based on the AIP coordinates:

https://cimg3.ibsrv.net/gimg/pprune....3975fc2686.jpg

Height and width are 1 minute of latitude and longitude, respectively, centre of the box is the above-quoted coordinates.

As for whether there is any discernable sign of the radio range remaining today, we would be looking for 4 points spaced more-or-less equidistantly around a 600 foot diameter circle.

Here's an example of one in the USA from GE - it looks like somebody has helpfully planted trees in the holes vacated by the antennae. :O

https://cimg5.ibsrv.net/gimg/pprune....9036a659d6.jpg

The Epsom one may well be under housing, or the golf course.

Ahhhhhhhh! Bloody decimals... I couldn't see how it could be THAT far wrong... Your box is roughly where I expected it to be and I was looking at old maps yesterday to see if it was marked (current OS 1/25000 maps certainly show VORs).

Incidentally, the three housing estates in the lower half of the box are all former mental hospital sites - there were five more or less adjacent to one another so I think the beacon would most likely be on the golf course site.

We can be a little more precise than that - the Aerad chart linked in post #15 shows EPM in its current location, based on the Biggin radial and the distance from Heathrow's OE.

The chart is dated May 1968, so it must have moved some time before then.

Thank you all for your interest and fascinating comments and nuggets information e.g. the EPM holding pattern, difference between OSGB36 and WGS84 and radio ranges. Especial thanks to Flap40 for great geometry and DaveReid and Discorde for their research. Belatedly, seeing those pins on the map reminded me of something which I had overlooked, having become fixated on my Epsom Downs theory. I used to live on the west side of Epsom and walked frequently in the former mental hospitals cluster. I vaguely recall a small brick building in the then farmland between West Park and Long Grove Hospitals. Also, I recall, but can't find, mention on local maps of a radio station in this vicinity. After a bit of digging (thank you National Library of Scotland!) I found an OS map published in 1962 showing a small fenced building at TQ 190 620. TQ 19 62 is the whole 1km grid square within DaveReidUK's red oblong so bottom left of that!

I've twice tried to send this post with a JPG of part of the OS map only for it to be rejected for apparently including a URL. Rather than risk it again I'll post the JPG separately.

Thanks again everyone!

Ockham85,

You won't be able to post URLs or images until you have ten posts. Here's the location you were referring to:
https://cimg0.ibsrv.net/gimg/pprune....f035399e6e.png

https://cimg1.ibsrv.net/gimg/pprune....6356207db1.png

Here's the map URL: https://maps.nls.uk/view/189258746 (Sheet TQ 16 SE, Six Inches to the Mile, 1962). The NLS site is a truly wonderful resource if you like old maps.

I estimated the 10m grid reference as TQ19036206 and converted it to WGS84 Lat/Long:
https://cimg7.ibsrv.net/gimg/pprune....58835e8d16.png
http://www.movable-type.co.uk/script...s-gridref.html

and then entered the Lat/Long into Google Earth:

https://cimg1.ibsrv.net/gimg/pprune....c297f50b6e.png


If you zoom in, you can see the outline of the foundations!
https://cimg9.ibsrv.net/gimg/pprune....7c91776de6.png


PS I have just noticed that the conversion website gave me the OSGB36 Lat/Longs as well. If you assume they are WGS84 coordinates and plot them on Google Earth, you would have a point 59 m S and 110 m W of the true position.

The line of trees on the western side of that field is the route of the Thames-Down Link national path from Tolworth to Dorking, which I walked a few years ago... Had I known then...

Tragic historic overtones​​​​​: it was during the left turn towards EPM that an unfortunate set of circumstances on 18/06/72 brought down Trident Papa India just outside Staines - the aircraft was following a Dover 1 departure.

Congratulations - great bit of detective work !

The rectangle on the map (strangely truncated by the grid line) presumably marked a wall or fence around the central antenna and hut. I suspect that by 1960 the radio range had been dismantled, leaving only the NDB, but if I'm not mistaken the orientation of the fence/wall matches the orientation of the original radio range beams. The Epsom beams were more-or-less at 90° to each other (though that wasn't necessarily the case for all radio ranges).

So the original four antennae would have been outside the rectangle, but in line with its vertices. Sadly, no trees planted in the holes. :O

Indeed, they look like not a lot more than a garden shed.

The truncation is caused by the map data to the east and west of the grid line being of differing dates. Have look a little further south where similar changes are evident in the mapping of Epsom Common.

...occupied by a Radio Ham...

The current site for EPM would be totally unsuitable for a Radio Range so it must have been on a different site at that time especially as the current building would not have been big enough to accommodate the range transmitters.

I have no knowledge of the Radio Range at Epsom, it predates me by many years, but at Dunsfold the Radio Range was converted into an NDB by retaining the original building and using the Range Mast nearest the building for the aerial. That arrangement continued until the early 80s when the remaining mast was condemned and replaced with the type of aerial now seen at EPM. The Dunsfold Range Building consisted of an equipment room next to a generator room with a firewall between the two which looks remarkably similar to the outline of the foundations in that field.

Originally at its current site EPM would have used a wire antenna strung between two fairly tall masts/poles either end of the compound. There aren't many en-route NDBs left but the building at EPM is at least brick built. Recent Google Map pictures of Westcott show something more akin to a horsebox.

Very close to the NDB was The Barwell Trading Estate where I spent many happy years employed in the family business. I also flew into the nearby farm strip in a Rallye Club and the (brave or insane) in a single Commanche. The brief for landing was 'just don't overfly the several mental homes for fear of disturbance!'. I was also told that the wartime PLUTO pipeline ran very close to both the farm and Trading Estate and I've attached an interesting reference to that. RAF Chessington (grass strip) was also very close but I was defeated in my efforts to fly in there!

https://cimg6.ibsrv.net/gimg/pprune....76d66f69c2.jpg

It's a bit outside my comfort zone, but I'd be surprised if the Epsom radio range used crossed-loop antennae - weren't they superseded fairly early on in the history of radio ranges by Adcock monopole arrays?

The Rushetts Farm strip in a Comanche must have been quite interesting - from memory several Pitts Specials came to grief there when visiting for maintenance by the late Geoff Masterton. I think one was fatal...