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Ekco Electronics
ARAA
Airport Radar Approach Aid
By Chris Poole - April 2008
 
The story of EKCO involvement in the above is interesting since it came about as a direct result of an early example of industrial/commerce co-operation between EKCO and Southend Municipal Airport.
The origin of ARAA lies indirectly with the Berlin Airlift of 1948/49 where GCA radar materially contributed to the success of the operation by allowing aircraft to operate in all but the worst conditions (particularly at Gatow and Templelhof airfields in Berlin) and proved that 'talkdown radar' was an invaluable aid to airports.
In November 1946, Squadron Leader Bernard Collins was appointed the manager of Southend Municipal Airport with the (enormous) task of developing the airport into a potential international airport despite having a very limited budget and shortage of materials.
In early 1949, noting the development and use of GCA radar in the Berlin Airlift, Bernard Collins realised that this equipment would be needed at Southend if it was to offer 'all weather' capability, however in 1948, GCA radar was hugely expensive (estimated to be circa £50,000) and by and large only the military and large international airports could afford it.
Daunted by this, Bernard Collins arranged a meeting with EKCO (Local folklore says that Eric Cole was at a luncheon with the Mayor of Southend and Bernard Collins) where the issue of GCA talkdown radar was discussed together with its high price and it was suggested to Eric Cole that surely he (E.K.Cole) could do something cheaper and just as good - being a local company and all that, to which, Eric apparently said 'I'm sure we can'.
The upshot of this was that 'Tony Martin' who by this time was Chief Engineer was tasked by Eric Cole to investigate the feasibility of designing a system, which would provide a talkdown service at a fraction of the cost of the existing systems.
Tony Martin at once realised that all existing GCA systems had been designed and built regardless of cost where radar had grown up in wartime when the military had unlimited money to lavish on it and each improvement was achieved by adding complication meaning that radar had bypassed the "primitive" early stages of its evolution.
Tony Martin therefore sat down with his team of engineers, lead by Ted O'Flynn (a wartime radar engineer with the company who ran a 'special projects' laboratory above the car radio laboratory at Southend) and started to backtrack, trying to design the simple radar that might have been developed in the early days if military money had not been so plentiful. Here the work was made much easier by the fact that at Malmesbury work was well ahead on a radar system for Hawker Hunter Radar Ranging and ASV Mark 19 for the Fairey Gannet.
Tony Martin and Ted O'Flynn along with another engineer John Price assisted by Mike Foggarty and Bernard 'Johnny' Walker established the parameters needed by the airport Air Traffic Controllers through a series of meetings with Bernard Collins (mostly in a pub according to local folklore), these being that the radar must have a means to positively acquire and identify an aircraft (in other words - a means to scan the surrounding sky) at a minimum of 10 miles and a means to accurately talk down the aircraft on a 3 degree glide-path to the Obstacle Clearance Limit height of 250 feet (at 1/2 mile from touch-down) at which time the runway lights should be visible failing which, the aircraft was required to abort the landing and overshoot to either try again or divert to another airfield.
It just happened that the Hawker Hunter Radar Ranging (ARI-5820) system was an almost a perfect match in terms of radar performance since this 'X' band radar could meet the range requirements and had a high 'PRF' which could give the high resolution image needed to bring a 'target' down the glide-path when mated to the 5 inch 'high visibility CRT as used on ASV Mark 19.
All that was needed in terms of the radar performance was to decrease the beam-width to 3 degree's, which was simply done by increasing the antenna dish to 36 inches diameter (which also gave the extra range) and changing both the range marker generator and video output to show the required CRT indicator markers, which were generated by a counting system to show range markers at every 2 miles on the 0-16Nm range and every ½ mile on the 0-4Nm range 'A' scope.
The challenge then was to develop the hardware to suit the needs of a talkdown controller in a control tower and much discussion must have taken place with the controllers in Southend Control Tower via Bernard Collins.
The finished design was a structure, which has been likened to a periscope in a submarine in that the operator stood at a console, which was about 3ft square the front of which had a 5 inch diameter 'A' scope and an illuminated compass above together an illuminated series of lights, which told the approach controller if the aircraft was 'on track', or off to the left or right. Behind the front panel was the equipment rack containing the transmitter/receiver and the waveguide assembly.
The whole of this consol was mounted on a pole like structure, which was fixed to the floor via a bearing housing and the other end of this pole projected through the control tower roof above which was a small gearbox and the antenna dish. This pole also held the waveguide feed to the antenna and two 'Bowden' cables, which controlled the azimuth tilt of the antenna via (quite literally) two motorcycle twist grips, which in turn were attached to a modified motorcycle handlebar, this being the means by which the operator rotated the whole unit through 360 degree's (if necessary) so that all runways were covered.
Close-up of indicator unit showing the CRT, the compass above and indicator light console.
(still photo taken from Ekco film)
Southend tower in 1960 showing
scanner dish on roof
(still photo taken from Ekco film)
Also attached to the front of the control console was a fixed microphone linked to the tower radio (normally set to the approach frequency) and a wrap around curtain to keep out extraneous light or shadows falling onto the 'A' scope.
The upshot of this design was that the operator really did look like a submarine commander when operating the equipment.
The equipment gave a range of 16 miles and had two scales these being 0-16Nm for general acquisition and guidance and 0-4Nm for final precision talkdown. While no height information was given, these two scales did allow accurate distance information to be passed to the approaching aircraft via a graticule overlay on the screen, which compensated for the fact that the radar was not on the runway centre line. In the case of Southend, the control tower was about 800 yards offset from the main 06/24 runway. Once the parameters were decided on, development proceeded rapidly so that by June 1949, the first tests were taking place at the airport using a Percival Proctor owned by the airport as the target aircraft.
By June 1950, these radar tests were complete resulting in the system gaining CAA approval and certification in December 1951, thus allowing the system to be used operationally and it was demonstrated to the press in January of 1952. While the equipment was highly regarded by the operators who used it, and it was certainly cheap (believed to be circa £4,000 installed in the case of Southend Airport), it was never a best seller and probably no more than 30 were ever manufactured in the early to late 1950's.
The airports known to have installed ARAA are: Southend, Swansea, Leeds/Bradford, and Elstree. It is known that the RAF ordered 25 (apart from RAF Locking the details of the installations at other RAF bases is unknown) since in July 1952, the airport offered to train RAFVR operators for a year at a fee of £3675, which was accepted in September 1952, with the training finished by June 1953. In December 1952, Eric Cole and Tony Martin went to America at the invitation of the US Military who were interested in ARAA and to their surprise found that 'Time' magazine had run an article on the system, which was hugely satisfying to them. Unfortunately no sale was forthcoming from this visit. In 1960, the EKCO film unit recorded a visit to Southend Airport of the Mayor of Coventry and a delegation to view the Airport equipment described above.
This still from the Ekco film shows the Ekco Anson at just over 1.5Nm from touchdown.
Note the target moves from right to left.
Click here to view the Film. Despite the EKCO film of the Mayor and representatives of Coventry being shown the ARAA at Southend in 1960, it is not believed that Coventry Airport went ahead and bought it.
This lack of sales is not surprising as it has been described as 'the poor mans GCA' and it did not have the height finding and reporting of the mainstream systems, nevertheless it was an interesting project for EKCO and proved to be a very long-lasting and reliable system (possibly because of its simplicity) remaining in use at Southend until circa 1982.
An interesting footnote on the system at Southend is that the accuracy of the alignment had to routinely checked and while there were set protocols for alignment checking, it was not unknown in the later years of the checking at Southend Airport to ask one of the local (friendly) helicopter pilots to hover directly above a certain phone box, which happened to be directly on the centre line of 06 runway about 1 mile distant.

If anybody knows of further installations, particularly those at RAF stations, the author will be pleased to hear from you.

 
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