Site Records

Site Name: RAF Fylingdales

Snod Hill
North Yorkshire
OS Grid Ref: SE865975

Photo: The SSPAR
Photo by Nick Catford

Fylingdales is a long-range radar station, which forms part of the Ballistic Missile Early Warning System (BMEWS) and Space Surveillance Network (SSN). Fylingdales was the third and last of the BMEWS stations to be built. The first two are at Thule, Greenland and Clear, Alaska.

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SSPAR at Thule, Greenland

Modern SSPAR and 'golfballs' in background
Modern SSPAR and 'golfballs' in background

© Skyscan Balloon Photography.

The three famous `golfball' radars were manufactured by RCA and installed in 1963. Each radome, to give the pale blue golfball its official term, contained an 84 ft. diameter parabolic dish antenna.

Two of the radars would track from side to side, one looking for targets at an elevation of 2.5° above the horizontal and the other at 5°. If a target was `painted' at 2.5° and then 5°, it might be a rocket in its boost phase, so the target would then be tracked by the third radar until its trajectory and any point of impact could be calculated.

As well as its early-warning and space-tracking roles, Fylingdales has a third function. It keeps track of spy satellites used by other countries, so that secret activities in the UK can be carried out when they are not overhead. The armed services, defence manufacturers and research organisations, including universities, take advantage of this facility.

Fylingdales was also an important site in the North Atlantic Radio System (NARS) - a `troposcatter' radio network which connected to the USA via stations at Mormond Hill in Aberdeenshire, the Faroes, Iceland, Greenland and Canada. Later a southern link to Martlesham Heath near Ipswich was added, codenamed Project Tea Bag!

In its early years, Fylingdales would have been the source of the so-called `four-minute warning'. In reality, the expected warning time was three minutes. For many years it has been more likely that the first warning would come from a satellite.

According to US Spectrum Requirements: Projections and Trends, a document published by the US government's National Telecommunications & Information Administration all three BMEWS radars operate in the 420 - 450 MHz frequency band.

The station is the subject of two treaties between the UK and USA, signed in 1960 and 1979.

In recent years the original `golfball' radars have been replaced by a solid-state phased-array radar (SSPAR), built by Raytheon. This radar consists of a three-sided truncated pyramid about 120 feet high. Each face is about 84ft across and contains an array of 2,560 transmit/receive modules each with a circularly-polarised `Pawsey stub' antenna. Each module produces a transmitter power of 340 Watts and this gives an overall mean power output from the three faces of 2.5 Megawatts - a very similar performance to the old golfballs. The new radar has the same 3000 mile range as the old one. It was declared operational on 1st October 1992.

On a visit to RAF Fylingdales in 1997, RSG members were told that the radar's software is designed to ignore targets that do not behave like a rocket being launched or a satellite in orbit. It is little surprise, therefore, that the RAF says that the station has never detected a UFO in flight!

Another phased-array radar system provides a similar capability, for both missile early warning and space tracking, in the southern USA. These stations are designed to detect submarine-launched ballistic missiles (SLBMs). This network, known as Pave Paws, has four stations in California, Texas, Georgia and Massachussets.

Fylingdales is unique, however, in that it is the only SSPAR with three active faces and 360° of coverage in azimuth.

Please note: This is an active MOD site.

RSG site visit 11th October 2002

[Source: Andrew Smith]

RAF Fylingdales is located alongside the A169 north of Pickering and easily identified by the 'pyramid' seen from the road. We started with a windscreen tour of the site including the fire station, police station, power house, Serco workshops and former site of the now long gone 'golfball' radar arrays. Our guide was one of the site Warrant Officers for this part of the tour.

We were informed that there were some 400 personnel on site of which the majority were contractors from Serco with only 75 RAF staff the majority of which lived off site. There is a single USAF liaison officer who has 9 US civilians working with him as contractors. The MOD guard service has 19 staff and the MOD police is 60 strong but is being increased to 100 due to the risk of peace protesters invading the site (there is a small camp nearby). The site has a MOD Police checkpoint by the road and a further checkpoints at each of the fences. The outer fence is topped by an 8000 volt electrified section and all entrance gates can be locked and razor wire placed in the opening on large metal truss frames. Having finished the tour in the bus we disembarked at the main SSPAR (Solid State Phased Array Radar) 'pyramid' building and went in via the 2 security gates. We then took the lift to the briefing room on the second floor. Here we were met by the base commander who welcomed us and gave us a highly detailed and very entertaining presentation on the history of the site and its' current role and function.

We were handed examples of the radar emitters and the transmitters and receivers. Unfortunately these were not available to purchase from the souvenir shop!

The site was originally going to be on Fylingdales moor a few miles up the road but prior to building commencing concern was expressed that the site was right on the cliff edge and therefore very vulnerable to attack from a RPG or similar fired from a boat. The decision was therefore taken to move it inland a little way and the current site was selected. This is Snod Hill and rather than name the site 'RAF Snod' the Fylingdales name was retained.

The site first became live in 1962 and the 'golfballs' were replaced by the SSPAR in 1992. Each of the golfballs had a radar dish in it which constantly panned back and forth scanning the sky. This system was accurate to detect a single object within 240 nautical miles and could track a modest number of objects simultaneously.

The SSPAR can track object as small as 0.5sqm and has a separation range of 1000 yards. It can track up to 800 objects at the same time.

After the talk there was a lengthy question and answer session including questions on the protection factor of the buildings. The main bunker has 3 metre thick walls and the entire pyramid is fully shielded against EMP. In the event of a ballistic missile attack the role of Fylingdales is to provide information on the number and direction of inbound missiles to the Nuclear Ops. Tasking Centre, Defence Crisis Management Centre, UK Strike Command and also to the US at NORAD and NATO. There are 2 other similar radar's at Thule in Greenland and a site at Clear in Alaska but Fylingdales has 360 degree coverage and an effective tracking range of 3000 miles. Should the site be hit by an in bound missile then it's role would be taken over by one of the other radar's.

We then commenced the tour of the building. We left the presentation room and took the lift up a couple of floors to the power room. Here we saw the feeds from each of the radar emitters enter it's control cabinet and we viewed the terminal system that gave constant status on each of the array faces.

From here we walked into the next room which was looking onto the rear of one of the array faces. Our guide explained that the radar 'pulses' its' signal and that this pulsing requires huge bursts of current. The site has it's own power station (and bore hole) and does not rely on the national grid. The transmitters have huge capacitors which store the current and can then discharge it when the face pulses and we could see this happening on the power gauges by each section of the array. Our guide explained that this method stopped the lights going dim every couple of seconds!! Each face has some 2750 array emitters but only 2500 actually work. This is to 'shape' the radar beam and each of the emitters has a heating coil which can be switched on to help prevent the build up of snow and ice (very useful up there).

From the face we returned to the lift and went down to the ground floor where we entered through a huge blast door into the bunker. Having passed the blast door we passed 2 gas tight doors and walked down a corridor to the main ops. room.

Sspar radar face at Eldarado, Texas before
moving to Clear, Alaska. Photo by Rayathon

On entering the room we were greeted with a cheery 'hello' from the RAF staff at their stations and the Crew Chief split us up in small groups to go to the various workstations where we would be given an explanation of the display system. Our operator on terminal 4B was a very nice young lady in RAF uniform (steady lads!) and we received a very extensive explanation of what we were seeing on screen. Whenever the radar detects an object it searches its' registry for an identical course and speed. If it finds a direct match it tags the item on screen with a number and the operator can watch it track until it goes out of range. If the item is unidentified then it will alert the operator who can then run a series of checks for interference etc. to confirm if the object is genuine or not. At this point a 60 second clock starts ticking on screen during which time the commanding officer must make a decision as to if the object is a 'validated launch' or not.

Our hosts ran a tape of a missile launch from the Barents sea which had been recorded some time earlier and we were able to see the plot appear on screen and follow the drill and identification of the object to validation point.

We all asked heaps of questions and were told that there had not been a validated launch call for at least 3 years although one was made some time ago when a Soviet Typhoon class submarine launched a test missile from the polar ice cap towards Russia. Normally all sides involved in test launches of ballistic missiles notifies everyone else so as not to cause false alarms of attack. On this occasion the Russians hadn't informed anybody and tensions was said to have been 'high.'

All too soon we had to go back to the bus but we ended up at the on site bar where we consumed tea, biccies and lager.

For a site plan of Fylingdales click here

[Source: Andrew Smith]

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Last updated 2nd September 2003

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