Decca Navigator closure ends an era

Aircraft Engineering and Aerospace Technology

ISSN: 0002-2667

Article publication date: 1 August 2000




(2000), "Decca Navigator closure ends an era", Aircraft Engineering and Aerospace Technology, Vol. 72 No. 4.



Emerald Group Publishing Limited

Copyright © 2000, MCB UP Limited

Decca Navigator closure ends an era

Decca Navigator closure ends an era

Keywords: Racal Tracs, Navigation, Positioning

After more than 50 years of providing radio positioning for mariners and aviators, the Decca Navigator system recently ceased to operate. The occasion was marked earlier by a farewell conference at Church House in London where users and pioneers of the system met to review the development of the technology and their experiences of its benefits.

During its lifetime the name Decca became a piece of nautical terminology that epitomised security and dependability. At its peak there were chains in all of the principal shipping areas of the world and an estimated 200,000 Decca users in Europe alone. By measuring the differences in signals received from transmitters along many of the world's coastlines, mariners and aviators were able to establish their positions with a degree of accuracy and consistency previously considered impossible. The advent of GPS navigation satellites eventually made the service superfluous and the General Lighthouse Authority, which had been funding Racal to maintain and operate the Decca chains, finally ended its support.

Speaking at the conference, Stephen Dark, director for Racal Tracs, said: "It is always sad when something good, that so many people had worked so hard to create, comes to an end. Decca Navigator was a huge success in its day but life moves on. Satellite positioning is with us now and happily Racal has not lost its lead. The company has built on its long experience to create the next generation of positioning technology".

Continuing, Stephen Dark said: "Racal was the first company to offer a commercial differential GPS (DGPS) service and the rest of the world followed us. Earlier this month we took the industry another major step forward when we announced a new Long Range RTK Differential GPS service. This enables our customers to know their position, accurate to within 20 centimetres, when they are up to 800km from the shore. Nothing like this has been achieved before and we believe that it is a clear indication of our intention to remain as the world leader in precise positioning technology".

Despite the free availability of GPS positioning, the withdrawal of the Decca service is still regretted by some sectors of the maritime industry. Most notably, fishermen valued Decca's ability to guide them back to fishing spots at sea with a degree of precision that is only available now through the more advanced Differential GPS services. Other sectors of the maritime community regret the loss of a positioning service that is totally independent.

The Decca Navigator system was first used in June 1944 when it was employed to guide ships leading the D-Day invasion through the huge minefield that protected the north coast of France. The difficulty of navigating a minesweeper in action across the English Channel and making a precise landfall at night was considered impossible without some form of radio navigation. The first Decca chain was therefore established on the south coast of England and began transmitting on the day before the invasion force landed. Had a radio navigation service not been available it is now believed that the D-Day invasion would have had to follow a completely different plan.

In 1945 the Decca service first became commercially available to users who would hire a receiver from the Decca Navigator company. By the early 1980s the widespread availability of low-cost microprocessors made inexpensive Decca receivers available for purchase. The loss of rental revenue caused Racal Electronics, which by then had acquired Decca Navigator, to inform the Government that it could no longer afford to operate the system without financial support. From then onwards the Decca Navigator Service was funded by the General Lighthouse Authority (GLA) and Racal continued to operate it on the Authority's behalf.

In 1992 an agreement was signed between the GLA and Racal-Decca Marine Navigation Ltd that the 18 Decca stations that had not already been modernised would be updated to reduce operating costs. This multi-million pound investment was completed by Racal in June 1994 by which time the entire system had been fully automated. Large buildings filled with valve technology transmitter equipment built in the 1960s were replaced by automated solid state units housed in small transportable containers. A new Supercontrol centre was opened in Edinburgh from which the entire UK Decca system could be monitored. Staff numbers were reduced from 64 to 19 and running costs were reduced by 40 per cent.

Despite the system operating within its reduced budget and successfully maintaining Decca Navigator's 99.95 per cent performance reliability, the writing was on the wall for the service. During 1999 the GLA announced the final shutdown of the service following over 50 years of successful operation.

Details available from: Racal Tracs Ltd. Tel: +44 (0) 20 8391 6511.

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