The History of Air Navigation Group commissioned the author to provide a brief account of airborne DR development by discussing both the methods and the equipment used in the air. This second and final part covers the period after 1940 which saw the automation of DR techniques from the Air Position Indicator of the 1940s to the Flight Management Systems in current use.

The History of Air Navigation Group commissioned the author to provide a brief account of airborne DR development by discussing both the methods and the equipment used in the air. This first part covers the period before 1940. The split is arbitrary, although it is obvious from a British perspective that military events around that date had a major impact on the pace of navigation development. However, it is equally obvious that airborne DR developed alongside a worldwide technical and intellectual revolution. This aspect of the story is abstract and involves some conjecture, so the paper takes it for granted and concentrates instead on practical matters. Accounts of air navigators' experiences as well as material on DR theory and descriptions of DR equipment in navigation manuals, journals and various surviving research documents have been used as the source material.

This paper outlines a technique to represent terrain using tree structures, based on Morton ordering to avoid the use of pointers. This approach enables terrain data to be organised in a hierarchical form affording a trade-off between the speed of access to the terrain database and resolution of the terrain data extracted from the tree. A set of database access algorithms is developed that form the basis of path extraction needed for real-time mission management. Several examples are presented to illustrate the performance of the routeing algorithms developed in the paper.

Recently, integration of different radionavigation systems has become very popular, since it improves system integrity, availability, accuracy and reliability. This paper discusses a new, flexible and cost-effective approach to system integration, centred on a single-chip application specific processor (ASP). An overview of this integrated system is presented and the application of the ASP for the implementation of a six-channel GPS, OMEGA, Loran-C and MLS receiver is given. The ASP is currently being implemented on a 180000 transistor 1·6μ, m CMOS Sea of Gates chip, and is expected to run at 100 MHz clock speed.

This paper, and the following one, were originally presented at an Institute afternoon meeting held at the RAF Museum, Hendon, on 5 June 1991. This first paper gives a personal view of the development and use of radionavigation techniques in the UK in World War II. The second paper gives some technical background to the systems discussed in the first one.