The Practical Combination of Air Navigation Techniques

Neither airborne self-contained nor ground-based air-navigation systems can by themselves completely meet the requirements of present day aircraft for both accuracy and continuity or positional and steering data. It is shown how dead-reckoning, providing continuity and reliability through the use of air-derived acceleration or velocity data, combined with intermittent ``fixing'' by employment of accurate position data obtained through the use of ground and stellar referenced sources, can increase operational capability without ``pressing the state of the art'' in any of the components of a system. Methods of inserting position fixes and of instrumenting the associated wind-computation and wind-memory functions are described and system errors are analyzed.