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Old 7th Sep 2011, 14:51   #1 (permalink)
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The development of Automatic Landing

Automatic landing or Autoland is taken for granted now. It has been suggested to me that an account of the pioneering work on its development, at the Blind Landing Experimental Unit (BLEU) of the Royal Aircraft Establishment (RAE), might be of interest to those with a taste for ancient history. I was at BLEU from 1955 to1958. This thread is a shortened version of a contribution I made to Wikipedia on Autoland, Sections 2.4 and 2.5 (with references). Apart from that, I hope that other contributions to this thread will help to fill in some of the gaps.

The BLEU was formed at RAF Woodbridge and RAF Martlesham Heath during 1945 and 1946. ,The terms of reference were that the unit “will operate as a satellite of the RAE and will be responsible for the development on blind approach and landing of RAF, Naval and Civil aircraft”.

The subject of blind landing had been pursued with enthusiasm from much earlier. For example, in 1916 flight tests were made by the Royal Naval Air Service of an Aircraft Height Indicator, consisting of a weight attached to a length of cord, hanging from the aircraft. When the weight hit the ground the tension in the cord was relieved, triggering a switch to light a red lamp in the cockpit, so that the pilot knew it was time to start a flare out. The basis for BLEU’s work was however the development of autopilots at RAE during the 1930s. The Mark 4 was the wartime “George”.

Before the formation of BLEU, an automatic landing was made at the Telecommunications Flying Unit (TFU) of the TRE at RAF Defford in a Boeing 247D aircraft, DZ203, early in 1945, using the American SCS 51 radio guidance system. Although accounts of that event vary in detail, it is said to have been in complete darkness, with no landing lights and all other lights obscured by the wartime blackout. There was no flare-out - the low approach speed and shallow glide angle meant that the aircraft could be allowed to fly straight onto the ground.

SCS 51 was the basis for ILS, adopted by ICAO in 1948. Trials were made at Defford of an alternative system developed there. That was radar-based, which in effect gave range and height data to add to autopilot heading, so enabling automatic landing.

Research during the first few years at BLEU led to the conclusion that the most promising approach to blind landing would be a fully automatic system, and to the definition of the requirements for such a system. ILS was used as guidance during the approach phase, but at that time was not sufficiently accurate to complete the landing. That led to the development at BLEU of an improved FM radio altimeter for height guidance, capable of resolving height differences to 2 feet at low altitude, and a magnetic leader cable system for azimuth guidance. In collaboration with Smiths Industries Ltd., BLEU also developed coupling units to derive the commands to the autopilot from the guidance signals, and auto-throttle.

Components of the system were developed separately on several types of aircraft, including the Lancaster, Viking, Devon and Albemarle. A demonstration of the techniques used was given to military and government representatives in May 1949. Partially automatic landings had been made before then, but the generally accepted date for the first demonstration of the entire system including auto throttle, in a Devon, is 3rd July 1950. Over the next 20 years, BLEU in conjunction with UK industry and the UK airworthiness authority, continued the work needed to convert the concept of those experimental demonstrations into safe, accurate blind landings by large transport aircraft. The system in use now is, I understand, basically the same as that used experimentally in 1950.

During the early 1950s, as a preliminary to the further development of the full system, automatic approach trials were carried out on Valetta, Meteor and Canberra aircraft. The Canberra, VN799 (the prototype Canberra) was acquired in 1953 but was a write-off following a crash landing in August that year due to a double engine failure, possibly caused by a fuel leak, fortunately without serious injury to the crew.

At that time, Autoland had lower priority because efforts were concentrated on other projects including rapid landing of aircraft for RAF Fighter Command, visual aids for pilots, runway approach lighting and an approach aid using DME with Barbro. That changed when Operational Requirement 947 (OR947) for automatic landing on the V-force bomber fleet was issued in 1954. At that time the V-bomber force was the UK’s main contribution to the strategic nuclear power of the west and all-weather operation was essential. There was also renewed interest in automatic landing for civil aviation. As the next step in the development, the flare-out and coupling units from the Devon were linked to a Smiths Type D autopilot and installed in Varsity WF417, a much larger aircraft, capable of carrying 38 people rather than 10 in the Devon. The first fully automatic approach and landing was made by WF417 on 11 November 1954 under calm and misty conditions. A similar system was installed in Canberra WE189 to provide the first application of Autoland to jet aircraft. Automatic approaches and landings were recorded by WE189 early in 1956 but the development was interrupted in April when the facilities at Woodbridge, which had the only suitable leader cable installation, ceased to be available to BLEU. Development of auto-flare and automatic kicking-off drift was continued at RAF Wittering, but in September that year WE189, on an approach to its base at Martlesham Heath, crashed due to engine failure . The pilot, Flt. Lt. Les Coe, and the BLEU scientist in charge of the project, Mr. Joe Birkle, were killed.

Early in 1957 BLEU moved from Martlesham Heath to a newly equipped airfield at Thurleigh, the base for RAE Bedford. The development was continued in a third Canberra, WJ992, based on the results obtained with WE189. Experimental flights in WJ992 began late in 1957. I did most of the experimental flying, variously with four RAF pilots: Sqn. Ldr. John Greenland and Flt. Lts. Alf Camp, Alan Bountiff and “Pinkie” Stark. Automatic landing with auto-throttle was achieved by March 1958. Initially there were some problems with landing nose wheel first but by June things had improved - a note from my logbook reads “not bad - about 0.7 g nicely on main wheels - kicking off drift OK“. Then a week later: “Throttles off at 50ft. Very pleasing results” and on 20 August “hands and feet off” (that was with Alan Bountiff). By October 1958, when a further demonstration was given by BLEU, over 2,000 fully automatic landings had been made, mainly in the Canberra and Varsity aircraft. The demonstration by WJ992 can still be seen in this 1958 Pathé News clip (the airborne sequences are in a Varsity):


The V-bomber project to install and develop Autoland on Vulcan XA899, originally classified as Secret, ran in parallel with the Canberra and Varsity work. The first automatic landings in the Vulcan were made between December 1959 and April 1960. Trials were carried out later that year and the system was accepted for military service in 1961 - the first application of the Autoland system.

The Vulcan used leader cable but that was recognised as being impractical for general use. It was also known that it could be dispensed with if improvements could be made to ILS. Some improvement resulted from a narrow beam localizer aerial system developed by BLEU during the early 1950s and by 1958 automatic landings had been made using only ILS localiser for azimuth guidance. By the early 1960s radically new aerial designs for the ILS transmitters developed by Standard Telephones & Cables (ST&C) improved ILS to an extent that leader cable became obsolete.

For many years there had been discussions between the UK Ministry of Aviation and the US Federal Aviation Agency (FAA) on guidance aids for landing in poor visibility. The Americans favoured a “pilot in the loop” technique, with improved aids for the pilot, over the fully automatic system preferred in the UK. In 1961, to gain experience with “the BLEU automatic landing system” the FAA sent a Douglas DC-7 to RAE Bedford for the system to be installed and tested. After that and further tests on return to Atlantic City, the FAA were convinced and thereafter strongly supported a fully automatic solution to the all-weather problem, later to be adopted internationally.

Up to that stage the system had been realised only as “single-lane” or single channel, without any redundancy to protect against equipment failure. During the late 1950s and early 1960s increased cooperation between BLEU, the UK Civil Aviation Authority (CAA) and companies in the aviation industry with BEA and BOAC led to the definition of safety requirements in terms of a specification for maximum tolerable failure rates. In 1961, the UK Air Registration Board (ARB) of the CAA issued a working document BCAR 367 “Airworthiness Requirements for Autoflare and Automatic Landing” which formed the basis for the definitions for weather visibility categories adopted by ICAO in 1965. In 1959, contracts were placed by BEA and BOAC to develop automatic landing, based on Autoland, for the Trident and the VC10. The Trident used a triplex system with no common elements, so that a failure in one of the three channels could be detected and that channel eliminated. “Nuisance disconnects” were an early problem with that system, eventually solved by the industry, using torque switches with a controlled degree of lost motion. The introduction of Autoland for Category 3 operation in BEA’s Trident fleet required a huge effort by BEA, Hawker Siddeley Aviation, Smiths Industries and BLEU. A triplex system was also developed by Smiths and BLEU for the RAF’s Belfast freighter.

The VC10 used an Elliott duplicated monitored system. Later, the Concorde system was basically an improved version of the VC10 one, benefiting from advances in electronic circuit technology during the late 1960s. By 1980, the Trident had carried out more than 50,000 in-service automatic landings. The VC10 accrued 3,500 automatic landings before use of the system was curtailed in 1974 for economic reasons. By 1980, Concorde had performed nearly 1,500 automatic landings in passenger service. 10 years on from the 1958 demonstration, here is Pathé again with the VC10 - giving a much better impression of the system at work:


An earlier clip, from 1965 in Varsity 665, briefly shows the autopilot itself:


BLEU (renamed the Operational Systems Division of RAE in 1974) continued to play a leading role in the development of aircraft guidance systems, using a variety of aircraft including DH Comet, BAC 1-11 and HS 748 (to replace the Varsities, which had been the main “work horses“ for BLEU experiments for more than a decade) and VC-10 until the closure of RAE Bedford in 1994.

The development of the system for the Caravelle during the 1960s is another story, unknown to me, and I hope there will be contributions on it.

Last edited by REasson; 7th Sep 2011 at 23:01. Reason: removing broken (and unintended) links
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Old 7th Sep 2011, 15:14   #2 (permalink)
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Where do the B.E.A. Tridents feature in all of this interesting stuff?
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Old 7th Sep 2011, 15:21   #3 (permalink)
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Thanks very much, RE, most interesting.
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Old 7th Sep 2011, 15:47   #4 (permalink)
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BEA Trident

Considerably. The Trident and the VC10 were the first airliners to be fitted with Autoland in collaboration with BLEU. The Trident was the first one to do an automatic landing, in 1965, and was certified to use it for CAT II conditions in 1968, a few months earlier than the certification of the Caravelle for CAT III. The Trident was certified for CAT IIIA and B in 1972 and 1975.

There is a full account about the Trident (up to 1970) in:

K. J. Wilkinson (1970) Automatic Landing in BEA’s Trident Operations - a Review of Effort and achievement, The Aeronautical Journal, March 1970, Vol. 74, Number 711, pp. 187 - 196

but I don't know if that is available in cyberspace.

Roy Easson
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Old 7th Sep 2011, 15:49   #5 (permalink)

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The BEA Tridents were the first aircraft to be cleared for auto land with pax. BLEU not surprisingly were responsible for arguing the case for such an approval as well as the detailed tecnical analysis that allowed the ARB (and ICAO) to agree to it.
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Old 7th Sep 2011, 16:29   #6 (permalink)
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I think I am correct in saying that when the Shorts Belfast was undergoing autoland development trials they actually had to build a scatter into the system as it was 'allegedly' so accurate it was landing at exactly the same point each time and cracking the runway.
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Old 7th Sep 2011, 18:02   #7 (permalink)
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Absolutely correct; Belfast XR364 did more than 800 autolands at Bedford. The system (Smiths SEP5 Triplex Autoland System) was very similar to that fitted to the Trident.
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Old 7th Sep 2011, 18:30   #8 (permalink)
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I forget the name of the manufacturer of the BA TriStar Autoland system. Suffice to say that it was regarded as PFM!

I recall, many years ago, the thirty-or-so approaches we made into Bedford to (re)evaluate the RAF TriStar Autoland System. Quite why we had to attempt to reinvent the wheel I'll never understand. However, not unlike the Belfast, the scatter was minimal and that there were concerns about the pavement strength of Brize Norton and whether or not it was financially viable to allow Autoland to be routinely used.

In the end I believe that it was a "certification" issue that resulted in the RAF TriStar's not to be cleared for Autoland use.

Before any of the expected comments appear with regard to the damaged aircraft that did attempt an Autoland at Brize... that particular attempt was made by a pilot who hadn't been trained in the use of Autoland and that he attempted Glideslope Capture within the region of 500 ft or so... destined to failure! And a very expensive fix!

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Old 7th Sep 2011, 18:56   #9 (permalink)
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I well remember the BLEU Varsity flogging the circuit around Bedford in the mid 60's. I think I have posted on this before but, in 65, I took on a chemist to work permanent nightshift in Bedford. Before he started and got the local flavour of the neighbourhood, he bought a house in the country to give him peace and quiet for sleep during the daytime. Too late, he found that he was on the centre line of the Thurleigh runway and suffered perpetual noise from the Varsity. When the weather was bad, there was no respite because they flew even more.
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Old 7th Sep 2011, 19:00   #10 (permalink)
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To me the greatest disappointment is that the prime driver for BEA being in the forefront of this technology was to improve the reliability of their trunk domestic services operating into Heathrow during poor weather conditions, hence why so much BEA money and management time was input.

Roll on to nowadays and Heathrow is now so squeezed for throughput at all hours that with the slight reduction in runway capacity required for such low visibility operations, those very same (now BA) domestic services are always the first to get delayed or binned completely whenever conditions fall to those which inspired this development in the first place.
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Old 8th Sep 2011, 02:41   #11 (permalink)
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From the days (around 1962) when we first got the Trident as when it had the basic auto/pilot of 2 pitch and 1 roll or was it 1 pitch and 2 roll (it was a long time ago) I as an electrical /instrument fitter on the Trident 1s in the central area and saw its development to the Cat 3 standard and until its demise, it was an expensive piece of kit everything in triplex except for the Air data computers the gyros were costed at £3000 each and you could by a small house for that at that time and the aircraft had to have fully separate generator electrical supplies but when it was working and it became reliable it did save alot of diversions to Stanstead ,Gatwick and airfields further north with the ground engineering having to go and retrieve them when there was fog at London, and passengers when they landed in fog at London were left wondering how they were getting home as the fog was making drivng hazardous and most traffic was at a stand still.We were very proud of it .
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Old 8th Sep 2011, 05:38   #12 (permalink)
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Leader cable

A very intresting concept, an induction cable similar to the guided vehicles in big factories.

Is there any more history in relation to this system.

Any remains on site.....

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Old 8th Sep 2011, 06:10   #13 (permalink)
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There is a Trident three (G-AWZI) nose section on display at the Farnborough Air Sciences Trust (FAST) Museum at Farnborough airport along with a small exhibition on auto-land and the RAE's involvement. Well worth a visit the musuem is FREE to enter and open weekends 1000-1600; most weekends the Trident is opened and powered up for viewing. The instrument, ceiling and floor lights are all operable along with some of her systems such as the stick shaker, engine fire bell and stall warning horn. She is complete and as would have been in service with BEA / BA.
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Old 8th Sep 2011, 12:56   #14 (permalink)
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Leader Cable

As for history, I believe it was based on a system developed during WW1 for guiding ships. And remains - again I think it was installed at about 12 RAF stations, but I expect even if the cables were not recovered they've long since all been stolen. But for Autoland it really was a cul de sac.
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Old 8th Sep 2011, 13:36   #15 (permalink)
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Originally Posted by REasson View Post
The development of the system for the Caravelle during the 1960s is another story, unknown to me, and I hope there will be contributions on it.
There is some detail of the French Caravelle autoland here in an old Flight magazine

automatic landing | flight systems | marconi mechanical | 1963 | 0036 | Flight Archive

There's probably a bit more to be found digging around other issues.

If I recall correctly the driver of the Caravelle development was the same as the BEA desire, to improve the performance of trunk domestc services in foggy conditions (which seemed much more prevalent in the 1960s than nowadays). The main air route afflicted was Air Inter's Paris to Lyon, which apparently suffered extensively at both ends in the winter, and compared to nowadays had a very large air service, as the TGV rail line which has now taken most of the traffic between these points was something far in the future.
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Old 8th Sep 2011, 13:57   #16 (permalink)
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Adding to the excellent first post; in 1974 BLEU became Flight Systems 2 (FS2), part of Operational Systems Division, FS1 was the old Aero Flight. The two amalgamated into Flight Systems Squadron circ 1976/77.

The All Weather Operations research continued with the Economic Category 3 Programme (1975-1980) using the BAC1-11 and HS748.
The BAC1-11 retained ‘2 out of 3’ channels of the Smiths SEP5 ‘Trident’ autopilot and the autothrottle, but the FD was a single cue FD108. The research concentrated on human capabilities of manual landing in low visibility if a simpler (cheaper) flight guidance system failed. This work also considered the problems of low altitude manual go-arounds.
The HS748 retained the Smiths Series 6 autopilot/autothrottle and split cue FD which enabled auto and manual Cat 2. A new simplex monitored autoland module was developed for the Economic Cat 3 work, although many fog landings were completed manually from a DH of 50ft.
Both aircraft could be equipped with an airborne fog simulation – a pitch/roll stabilised ‘fog blind’ and translucent screens. Late in the programme a Monohud was evaluated, again available for both aircraft.

A lot of parallel research was flown in support of the lighting division, where approach and runway lighting, PAPI, and runway markings were developed. That team also worked on the structure of fog, and the measurement and reporting of RVR.

In the late 70’s money was drying up so other research programmes were sought. Both the BAC1-11 and HS748 were used for the UK MLS trials, with the HS748 demonstrating the system in Berne and Tehran; this work also continued previous research into steep and two stage approaches with associated noise measurement.

There was some parallel AWO work with helicopters, primarily for naval operations; this was extended into the Harrier trials for seaborne operations.

The BAC1-11 had a versatile autopilot facility – a programmable addition to the existing flight guidance system. This work looked at new control laws and methods of control – alpha autothrottle, direct lift control, and the basis of fly by wire systems with artificially reduced longitudinal static stability. An early design of FMS was fitted and RNAV studied; the flight deck was converted to EFIS in 1979/80.
The HS 748 conducted some low level electro–optic trials for a military operation using an existing ‘fog’ LLTV.

I sense that the ‘BLEU’ fog / autoland work petered out in the 80s.
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Old 8th Sep 2011, 14:02   #17 (permalink)
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I've got a page on my website about the VC10 autoland system which includes the same Pathe clip. See here: Autoland on the VC10

It also includes a link to a story of an ex-Avionics engineer who explains why the system's use was discontinued on the VC10.
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Old 8th Sep 2011, 15:00   #18 (permalink)
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More on Leader Cable

According to Michael D. Dobson ed., (2001), Wings over Thurleigh, ISBN 0-9541594-0-3 Chapter 8, Leader cable was installed at RAF airfields Scampton, Wittering, Finningley, Gaydon, Cottesmore, Wyton, Waddington, Conningsby, Benson & Honington. On the Vulcan, some time ago I found this in a post by Paddy Grogan:
"Some years following my retirement from the RAF I visited Greenham for an airshow and was permitted to go into the cockpit of a 50Sqdn Vulcan. When I began to touch the auto land switches etc My Flt Lt Pilot guide astounded me by saying " We dont know what they are for" They had never been used by him or anyone else on the squadron."

It seems that when submarines took over the strategic defence role, automatic landing ceased to be a requirement for the V-bombers. I suppose it is Secret as to whether the RAF uses automatic landing now.
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Old 8th Sep 2011, 15:32   #19 (permalink)
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Caravelle Automatic Landing

Thanks for that clue. Searching Google on the same subject revealed this, which has more detail (also on the Belfast)

1967 | 0371 | Flight Archive
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Old 8th Sep 2011, 20:42   #20 (permalink)
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I believe the L1011 used a Lear Seigler autopilot and autoland system.
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