Saturday, 1 June 2013

Air Ministry Experimental Station (AMES) 713 – LORAN on Unst (updated 22 Jun 13)

During WWII a number of new, highly classified navigation systems were employed by the RAF, particularly by aircrews in Bomber and Coastal Commands. In the early part of the war it was soon discovered that the accuracy achieved on most bombing missions was abysmal – obviously the information was not made available to the general public. Throughout the war a number of British developments came on line to help navigation and bombing accuracy – GEE, OBOE, H2S etc. These combined with new operational techniques, such as the formation of the Pathfinder Force, ensured that precision improved as time went.


Coastal Command was also in great need of the ability to fix positions accurately. Flights often lasted many hours over water, without physical features to help with navigation. Sunderlands could be airborne for 10 hours, the Liberators maybe 15 and the Catalinas (& Cansos) up to 20 hours – plenty of time for unpredictable winds to embarrass navigators.  To make a rendezvous or to report a sighting, sometimes hundreds of miles from land,  required efficient systems and operators.

Scientists in the USA at the Massachusetts Institute of Technology (usually referred to as MIT), developed a different navigation system, originally called the Loomis Radio Navigation system (LRN) after its developer, Alfred Lee Loomis. The acronym was soon changed to LORAN, which stood for Long Range Navigation.  The LORAN system was inspired by, and similar to, GEE - but had different performance characteristics. There was British involvement in the MIT developments from the beginning, partly to ensure that an airborne receiver was produced which could fit into the same space as the GEE receivers carried on board UK aircraft.
Whilst LORAN weas not as accurate as GEE (LORAN + or - 1% of the distance from the transmitter), it had a far greater range. GEE had a range of about 300 miles whilst, because of its longer wavelength, LORAN could achieve ranges of 700miles in daytime. At night time, with the transmitted signal bouncing off the ionosphere, ranges of 1,400 miles were regularly achieved.  This advantage made the system highly desirable to naval forces and to aircraft on long range missions.  Like some of the other systems LORAN was passive for the receiving platform, users could get a fix if their receiver was switched on - there was no need to transmit with the possibility of giving away their position.

LORAN was what was known as a hyperbolic navigation system, there have been a number of them including GEE, Decca Navigator, Omega etc. There are plenty of places where this type of system is explained, including Wikipedia. I will leave those who are interested to explore for themselves – I have included a number of source documents at the end.
Like GEE the LORAN system needed a “master” station and a number of “slave” stations. Each station in the chain had to transmit its pulses in coordination with the others. The “master” station sent out timing signals to its “slave” units so these units needed receiving aerials as well as their transmitting aerials. For those of you who are interested in the early LORAN systems and have a more technical background than me, there is an excellent (free) publication from MIT – which was first issued in 1948 – available at the web site below. However, the document is in .pdf format and is over 450 pages long – it will take a while to open or download!
Worldwide most LORAN sites were operated by the US Coastguard but sets of the American equipment were shipped to Britain and were operated by British personnel. When installed the sites were given numbers in the Air Ministry Experimental Station (AMES) 700 series – the one on Outer Skaw being AMES 713. The site was established at the specific request of the RAF to cover Norway. Among the other sites there were RAF Units at Scousbrough, on the Shetland Mainland, at Burifa Hill, near Dunnet Head and at Port Errol, near Cruden Bay. A site at Mangersta, Lewis – south of the later Rotor Site of RAF Aird Uig –was operated by RN personnel. Most LORAN chains had a “master” and a minimum of 2 “slave” stations. The extract from the MIT-Radiation Lab Series Vol 4 Long Range Navigation-LORAN below shows the complete North Atlantic Chain: (Left click on pictures to enlarge)
The M/S in the second column refers to the role of the station – Master or Slave.
Skaw (AMES 713) was also part of what was known as the North-East Atlantic Chain. This Chain had Skuvanes in Faroes as the master station and Vik in Iceland, Mangersta in the Hebrides and Skaw in Unst as the slave stations. There were 2 “monitor” stations in this chain checking the synchronisation of pulse timing – these were at Scousburgh on the Shetland Mainland and later at Burifa Hill, near Dunnet Head close to the site of the Admiralty Experimental Station (AES6) with its Coastal Defence U Boat Radar.
The sites were numbered:
AMES 713 – Skaw
AMES 714 – Mangersta
AMES 715 – Vik
AMES 716 – Skuvanes (Sometimes referred to as Vaag, Vag or Vagur

AMES 7?? – Scousburgh (Monitor)
AMES 702 – Burifa Hill (Monitor - took over from Scousburgh)
On 21 Jul 44 a siting party arrive on Unst to select a location for a LORAN installation. The site chosen was on the headland of Outer Skaw, just over 2 miles east of the summit of Saxa Vord. The area had been home to the RAF Skaw Reserve CH site but that had closed and the equipment removed earlier in the year. The Transmitter and Receiver Buildings had been demolished and two 120’ wooden Chain Home aerials dismantled. 

A new combined Transmitter /Receiver Building was constructed on the site of the Reserve Transmitter Building. This consisted of a 36’x16’ Nissen Hut behind a blast wall and was simply known to personnel as the Ops Block.  Explosives had to be used to remove rock, increasing the floor area available and to provide a new sloping access route at the north end of the building.  The Nissen Hut was complete by 31 Aug 44. A new 120’ wooden tower was erected on the site of the Reserve Receiver mast but this was for the LORAN Transmitter antenna; construction was completed on 11 Sep 44.
As mentioned earlier, it was essential that transmissions were synchronised with other units in the chain. To achieve this synchronisation a receiver aerial was required. In fact the unit on Outer Skaw had 2 receiver aerials. The first was hung from a 65’ vertical pole and was erected on 25 Sep 44. The second was a 300 yard long horizontal beverage array; I presume constructed at about the same time the vertical aerial. This consisted of a long copper wire attached to posts in a straight line and probably 6’ to 10’ above the ground. Only one of the receiving aerials would be used at a time – the choice dependent upon atmospheric conditions. Three Lister 20KVA Generators were installed in the disused RAF Skaw Remote Reserve Power House, which had been left standing.
Technical aspects of the equipment and site were the responsibility of Headquarters 60 Group and the individual responsible for Shetland radar and navigation installations in this period was Flight Lieutenant Firmin. Flight Lieutenant Firmin visited Shetland sites on a number of occasions and was at Outer Skaw from 16 to 22 Aug 44 to supervise the erection of Buildings and to give advice on technical matters. I am not sure how the heavy equipment arrived on site. Currently at the end of the road which leads back to the RAF Skaw main site (and all places south) is an old wooden bridge, whether this bridge or a predecessor was used I don’t know. A photo of the bridge is below – the Power House is the larger of the 2 buildings on the horizon, just right of centre.
The area of the LORAN site is shown in the following Flash Earth Image:
 
On air testing of the site began on 3 Nov 44 and, from 10.00 on the 7 Nov, a full 24hr test transmission took place. AMES 713 became operational with effect from 13 Nov 44.
Relationship between AMES 713 and RAF Skaw Chain Home Station
The full establishment of the LORAN Unit was:
Commanding Officer - 1 x Flying Officer (Technical)
Mechanics – 12 – rank structure unknown but it included at least 1 Sergeant & 1 Corporal
Operators - 13 (watches appear to have been 1 Sergeant, 1 Cpl and 1 or 2 LACs)
Total establishment – 26
As with modern day military units, the number of personnel on strength did not necessarily match the number of people who were supposed to be on the Unit. There were also a number of attachments/detachments.  The total number of personnel at RAF Skaw CH site would have been in the region of 150 to 200.
The two stations sat on adjacent headlands which, in a direct line, were approximately a mile apart. Apart from the Commanding Officer, the establishment of the LORAN site was for mechanics and operators. AMES 713 was therefore totally dependent upon RAF Skaw for accommodation, admin, messing, MT etc. It is probable that the LORAN personnel had their own billets, but in all other respects I think they mixed in with normal life on the RAF Skaw Domestic Site.
The AMES 713 personnel were involved in combined celebrations with their Skaw counterparts on VE Day, took part in station dances on the Skaw Domestic Site and had some participation in the welfare committee. The demarcation between the officers was rather blurred. I have listed a number of postings for Officers and SNCOs taken from the AMES 713 Operations Record Book. It records a number of movements at RAF Skaw as well and, at times the people involved appear to be interchangeable. I have used the terminology from the original document and this causes me some confusion as the terms Commanding Officer and Technical Officer at the LORAN Site apply to the same people and, at RAF Skaw, Flying Officer Beer is posted in as Commanding Officer and posted out as Adjutant!
AMES 713
6 Sep 44 - Flying Officer HW Porter arrived as Technical Office i/c Type 700 Equipment and its installation
8 Feb 45 - Sgt Waldock (Senior Radio Mechanic) took over command.  (Fg Off Porter detached)
12 Feb 45 - Sgt Cheaser (Senior Radio Mechanic) took command. (Sgt Waldock posted to Renscombe, Dorset)
28 Mar 45 - Flying Officer HW Porter back from detachment. (Included 5 weeks at Terceira in the Azores where he had been investigating the possible siting of another LORAN Station)
7 Sep 45 – Flying Officer HW Porter posted out to the Faeroes
14 Sep 45 – Flying Officer Baldwin posted in as Technical Officer at 713.
RAF Skaw
18 Apr 45 - Flt Lt Prince posted out. 
18 Apr 45 - Flying Officer HW Porter takes administrative command of RAF Skaw
15 May45 – Flying Officer GT Beer posted in as Commanding Officer RAF Skaw
11 Sep 45 – Flying Officer Beer (adjutant!!) posted out (to HQ 70 Wing)
14 Sep 45 – Flying Officer JF Ledingham posted in to take command of the station.
16 Oct 45 – Flying Officer JF  Ledingham, Officer Commanding RAF Skaw, posted out (to HQ 70 Wing
16 Oct 45 – Flying Officer Baldwin assumed command RAF Skaw.
I have highlighted a couple of names of people who are shown to have had responsibility at both stations. I also noticed that Flying Officer Baldwin, who assumed command of RAF Skaw on 16 Oct 45 still signed the AMES 713 ORB at the end of Nov 45 as “Technical Officer, Station 713, Skaw”
I think the preceding paragraphs indicate that the 2 sites were very closely linked.  I also suspect that the personnel working on the LORAN equipment had many extra briefings on the Official Secrets Act and the sensitivity of their work, with frequent warnings not to discuss what they were doing when off-duty.
The Weather
There can be few servicemen returning home from a tour in Shetland who haven’t been impressed by the weather. On a good day Unst, in particular, is one of the best places in the world. However, there are some bad days and there seem to have been a few of them in the lifetime of AMES 713.
The watch coming on duty on the morning of the 20 Nov 44 found water 8” deep outside the door to the Ops block and all ducts filled to floor level – temporary drainage channels were quickly dug. Five days later there were severe northerly gales and torrential rain - water leaked into the Ops Block around the double doors at the north end of the building. Authorisation was given for a porch to be constructed (completed by 20 Dec 44, as were more permanent drainage channels around the block).
On 6 Dec 44 more severe weather was reported with icing 1.5” thick on the internal Domestic Site telephone lines – none of the telephone extensions worked and it was found that there was heavy static on the Beverage receiving array. On 18 Jan 45 nearly all the water pipes on the Domestic Site froze and on the following day all available hands were put to clearing the road to Baltasound to ensure fuel could get through. Again, on 2 and 3 Feb, it was freezing and there were NE gales – the road was considered unsafe and watch changes had to be done on foot. Much work had to be put in to maintain the roads on warmer days, the freezing and thawing had helped form ruts and potholes. As a final reminder of winter there were severe blizzard conditions with snow on 29 Apr 45, it was reputedly the worst April day on Unst since 1927.
EQUIPMENT
Transmission
The Transmitter Tower was in the NE corner of the site. It was a 120’ wooden tower and was mounted on the base seen in the next photo:
The actual antenna originally measured 107’ between the insulators but was cut to 105’ to achieve a better performance. Adding the braid to the coupling unit this was considered to give the transmitting aerial a total length of 111’. The aerial reached ground level in the structure known as the "dog house" , located between the bases of the four tower legs. At the start the tower had a ladder which only went up the first 40’, the rest of the climb to the top having to be made using step bolts on one corner of the tower. After pointing out to HQ 60 Gp in Nov 44 that this was unsafe in the Shetland climate with its frequent high winds, a work party finally arrived to extend the ladder in Jul 45. Below the tower, possibly on the surface or even slightly raised above it, would have been a pattern of up to 120 copper wires radiating a long distance outwards. At the extremities of these radials there was possibly another copper wire which formed a circle around the 120’ Tower. A number of grounding rods would have been planted at equal intervals around the circumference of this circle. This arrangement was to provide a reflective surface for the radio signals ensuring that the transmitted RF energy was distributed evenly in all directions. The picture which follows is an enhanced image from a photo taken by Andrew Laurenson, who was local to Unst. Andrew had been involved in the construction of RAF Skaw and, later on in 1947, was also involved in demolishing the site. I believe that the picture was taken from one of the CH towers – approximately one mile from the LORAN site. The 120’ Transmitter tower can be seen on the right of the picture:
 The transmitters were unpacked and installation commenced on 21 Oct 44. They were first tested on 25 Oct and operated satisfactorily.
Reception
As mentioned before there were 2 receiving antenna. However, unlike radar receivers they were not seeking a returned echo from a distant target they were there simply to pick up a timing signal from a transmitter at Skuvanes. This signal was to ensure that the transmitter pulses from Outer Skaw were exactly synchronised with those from the master station in the Faeroes. Only one of the receiving antennas could be used at a time and this required a special “Switching Unit”. The received signal was routed to the Ops block via a conduit – the route of which can be seen in the following photo:
Close to this would have been the 65’ vertical pole. This would have had a “cross-arm” at the top from which a copper antenna about 55’ long would have been suspended and attached to an anchor on the ground. Below the antenna there would have been a system of copper wires radiating outwards, possibly on the surface, There would have been about 60 radials, their length is unknown but it could have been as much as 125’. The purpose of this system would have been to ensure low resistance and to provide more constant antenna impedance in varying weather conditions.

Also close to the conduit would have been the eastern end of the 300 yard Beverage Array. This array would have consisted of a straight line of poles supporting a copper wire about 6’ to 10’ above the surface. These antennas are very directional and the axis would have been towards Skuvanes. This type of array can raise the ratio of received signal against atmospheric noise and, in some locations, could reduce static considerably. The component parts would have been relatively small and lightweight compared with the other 2 antenna on site and they have been removed from the site. The site of the eastern end of the array would have been close to the site of the 65’ vertical receiver pole and the Ops Hut. The orientation must have been slightly north of west as Skuvanes and Skaw, which are about 350 miles apart, lie on approximately the same line of latitude (Skuvanes 61.45N & Skaw 60.49N). I have not been able to locate either end of the array exactly, but it must have been postioned roughly where the blue line is on the  Flash Earth image wehich follows.


Once again there would have been a pattern of radiating copper wires around each end of this array.
Power
Most of the UK Loran sites were equipped with 2 Lister MkII 20KVA diesel generators. In places like Outer Skaw, where there was no mains power available from the national grid, a third generator was supplied. Two of the generators arrived on 18 Sep 44, with the third 2 days later. The decision to have extra capacity on the Unit was justified.
On 18 Dec 44 problems were found with the number 2 Generator, The fault was not identified and solved until 25 Dec when a component in the control panel was found to be burnt. On 18 and 19 Feb 45 “flash arcing was heard in the vicinity of the diesel switchboards”. This caused some fluctuations in the equipment and lighting before a cable fault was traced and repaired. The last significant power problem seems to have occurred on 21 Jun 42. The Number 3 Diesel had to be switched off as it was discovered that its foundations were unstable. After a new bed had been laid the generator was restarted on 7 Jul 45. All in all, the Unit appears to have had a more stable power supply than most of us living in Shetland nearly 70 years later. The picture below from Bob Jenner shows the type of generator which was used. The one in the photo is actually mounted on a frame, on an army trailer – the ones at Outer Skaw would have been on an RAF trailer but lifted off on site and installed in the Power House
The Power House, with the constant noise of the generators must have been a poor working environment. This was alleviated somewhat when an ante room for the watch-keeping diesel mechanics was completed (as then unfurnished) on 20 Dec 44. In Feb the Air Ministry Works Dept fitted guide ropes from the Power House to the Ops Block and then on to the Transmitter Tower – this safety measure was appreciated in the windy conditions occasionally experienced and at night time when the blackout conditions were strictly enforced.
Valves
Difficulties were experienced with a particular oscillator valve – VT98A. A number of these valves were unserviceable on delivery and others failed long before their designed life expectancy. The most frequent problem appeared to be broken filaments. The valve looked like this:
With permission from: www.tubecollector.org
It was a fairly substantial item measuring about 36cm x9 cm (14” x 3.5”) and weighed over 2 Kg (4.4lb). There were a number of references to the valve in the Operations Record Book, including this one from March 1945:
The supply chain would have been long and complex so it’s to be expected that there was concern over this issue.
Operations Block (Combined Transmitter /Receiver Block).
As already mentioned the Ops block was a 36’x 16’ Nissen Hut with a porch as a later addition at the north end of the building. My thanks to Bob Jenner for sending me the following sketch of a slightly larger US Coastguard Ops Block with a number of separate timer units. (US Quonset = UK Nissen)
AMES 713 had a Timer Units like the one in the picture below:
The Master station would transmit recurring pulses at a constant rate and it was the main function of the Timer to calculate the time taken for the pulses to reach the Slave Station and to trigger its own transmitter to ensure the transmissions were exactly synchronised with the Master. The Timer Unit/s would be within a screened area to reduce interference from other equipment. I’m grateful to Sqn Ldr Mike Dean MBE for allowing me to use the rare photo which follows. It was taken inside the Ops Room at Outer Skaw by the late David St George.  David was a serviceman who was posted to RAF Skaw as a Radar Mechanic during WWII and, due to the high security involved at the time; few such photos are likely to exist.
I note that there is a map of Shetland on the wall behind the operators. The site of the Ops Block can be seen in the next three recent photos:
Operations.  The effectiveness of the chain was totally dependent upon the exact synchronisation of the transmitted pulses from the stations involved. The Operations Record Book has numerous entries which show concern as to the signal from Skuvanes. The following example from Nov 1944 also refers to the Beverage antenna:
It is difficult to measure how useful AMES 713 was. We know that LORAN Chains further south were used in bomber raids flying as far east as Warsaw. We know that LORAN Chains were of great significance to naval forces in the Atlantic and Pacific Oceans. AMES 713 officially became operational on 13 Nov 44, the day after a force of Lancaster bombers, carrying Tallboy bombs, sank the Tirpitz (sister ship to the Bismarck), in a Norwegian Fiord. There were further airborne raids against German Forces in Norway, Mosquitoes attacking U-boat pens at Trondheim on 22 Nov 44 and Lancasters attacking another U-boat base and shipping at Bergen on 12 Jan 1945, for example. Whether or not these aircraft carried and used LORAN Receivers I don’t know but I think it was highly likely.
By the end of the war over 450 Coastal Command aircraft carried LORAN Receivers and many of these aircraft would have been working in the Shetland area. The search for U-boats continued to the end of the war. There were still convoys coming to the UK from the USA & Canada, some following northern routes passing just south of Faeroes. Between the time of AMES 713 becoming operational until the end of the war in Europe, there were 6 major convoys to and from Murmansk (outbound Convoy Nos JW62 to JW67). It’s not possible to quantify the worth of the LORAN site on Unst but I’ll guarantee there were numerous crews who were glad it was there.
AMES 713 became operational on 13 Nov 44 and had just 6 months in support of wartime military activities. The war in Europe ended in May 1945, with 8 May being declared as VE Day. There were still numerous maritime and aircraft movements in the area after that date and I’m sure that the LORAN on Outer Skaw continued to prove useful for some time. Developments to the LORAN system continued  and many units carried on for more than 50 years -the US system  not closing down until 2010 when it was considered that it could be replaced by GPS systems.
An extended life was not to be for the site at Outer Skaw.  Operations ceased on 1 Oct 45 and AMES 713 was put on care and maintenance in Feb 46. By the end of 1947 the equipment had been removed.
Acknowledgements
Bob Jenner
Gerry Firmin
Ian Brown
Mike Dean
Martin Briscoe
RAF Air Defence Radar Museum (http://www.radarmuseum.co.uk/)
Sources
Operations Record Book – Station 713, Skaw (TNA Air 29 – 167)
NOTES
I hope to keep this article as accurate and as informative as possible. If you have noticed any mistakes or have material you think I should add I would be pleased to hear from you – gordon.carleATgmail.com  (replace AT with the usual symbol). I thought it might be helpful to provide a little information about some of the places and people mentioned in the text and in the Operations Record Book. Once again I will be happy to amend inaccuracies.
Scousburgh.  Scousburgh was a GEE Slave Station (AMES 7000 series).  Located on the Shetland mainland, close to what was later to become the Mossy Hill Ace High site, it also had LORAN (AMES 700 series) equipment.  It appears that the equipment was installed as monitor for the NE Atlantic Chain. My evidence for this is a short entry in the AMES 713 ORB which states
22 Dec 44 – Scousburgh becomes a North East Atlantic Chain Monitor, rather than merely a stooge for station 713. From today two receivers are to be kept humming with difference readings on the master and its three slave stations, with prejudice towards none.
Burifa Hill. Burifa Hill was another GEE Station (AMES 7000 series). It was near Dunnet Head and close to the site of Admiralty Experimental Station No 6 (AES6), a Royal Navy Coastal Defence Radar Unit. It was a Master Station in a GEE Chain with Windyheads in Aberdeenshire, Sango by Durness in NW Sutherland and Scousbrough in Shetland as its SLAVE Stations. The AMES 713 Operations Record Book first mentions Burifa Hill on 21 Jun 45 – “The new 700 monitor at Burifa Hill took over from Scousburgh at 18.00 hours”
Lorvick (sometimes spelled Lorvic). I believe this site is in Iceland and is more usually known as Vik - which was another Slave Site in the NE Atlantic Chain. There are a number of references to the site in the ORB; eg, on 31 Jan 45 – “The signal from LORVICK is still unsatisfactory, both here and at SCOUSBURGH, appearing only at night and then erratically
Mangersta. This was another Slave Station in the North Atlantic Chain with Skuvanes as its Master Station. It was set up before AMES 713, becoming operational early 1944. It was run by the Royal Navy with some technical assistance from the US Coastguard at the beginning. A short extract from a US Coastguard report from, 1944 – “I visited the Mangersta station on 11 February, and found security conditions at this station much the same as reported at Skuvanes Head station by Mr. Kopp. Local workmen are allowed to look over timer and transmitter equipment and the confidential instruction books are left lying in an open toolbox that is used by local civilian workmen. These conditions have been reported to the Admiralty and action has been promised. Arrangements are being made to give each man a double tot of rum at 1100 each morning. I suggested that the men on watch and the men about to go on watch have their portions held for them until they come off duty.”
Worth Matravers & Renscombe Down. RAF Worth Matravers in Dorset was an extremely important site in the war time development of radar. Not only were there both CH and CHL radars in the Purbeck area, but also in the area was a Gee site (part of the South West GEE Chain) an OBOE site, a LORAN Site and, until May 42, the former home of the Telecommunications Research Establishment (TRE). No 21 Signals Training Unit later moved into some of the TRE Buildings and was known as 21STU Renscombe Down.
Port Erroll. There was a LORAN Site at Port Erroll, near Cruden Bay in NE Scotland, but it was not operationally connected with AMES 713 and used the LORAN System differently. It was an SS LORAN site. SS LORAN stood for Sky-wave synchronised Long Range Navigation. It only worked at night and it was found that by using long base lines between Master and Slave stations great ranges could be achieved.  Port Erroll was a Master Station and was associated with a Slave Station at Bizerta in Tunisia. The US Coastguard had reports of ships at sea receiving useable sky wave fixes 2 to 3,000 miles from baselines using this technique. The system was obviously very useful for long range night time bombing missions.
Flt Lt FLC Firmin. As a civilian before the war Flt Lt Firmin had been involved in the Radio industry. For a while he was a member of the “Y” Service and then joined the RAFVR and was soon working with HQ 60 Group. The Group was formed early in 1940 and was to assume full control of Britain’s electronic home defence. At the time AMES 713 came into existence Firmin had the responsibility of overseeing all radar and all RAF Navigation Units north of Inverness. After the war Firmin had a long and distinguished career working for Marconi and was heavily involved in defence contracts at home and abroad. In 1968 he was awarded an MBE for his work at Marconi. A copy of of his rather cryptically worded “Y” Service certificate is below:-
 
A later photo of Len Firmin from a Marconi magazine )(via Sqn Ldr Mike Dean, MBE.
 
 

Flying Officer HWD Porter
I suspect that Flying Officer Porter must have been one of the early RAF experts in LORAN. The first mention of him that I have seen is in a letter dated 1 Jan 44 from the RAF Delegation in Washington to the Air Ministry. In the letter Porter and a number of servicemen are noted as embarking on a troopship in the US with 64 Cases marked Weasel and 47 cases marked Ant (LORAN components?). On arrival in UK he is told to leave the servicemen to oversee the unloading whilst he is to report to the Director of Radar at the Air Ministry.
He goes on to become the longest serving CO of AMES 713 (4 Sep 44 to 7 Sep 45). During this tour he is detached to help with the possible siting of a LORAN station in the Azores (owned by Portugal but a major transit point for British and American aircraft). On leaving Shetland he is posted to the Faeroes (quite possibly to the Master Station at Skuvanes, which is also manned by the RAF).

CONTENTS LIST