Navigation by bearing information

Abstract

A computer simulation model was developed and a series of experimental runs was conducted to investigate the technique of navigational fixing through the use of bearing information alone. It was determined that system bearing accuracies on the order of ± 0.50 degree will give fixing accuracies of 15 to 30 yards at ranges of 2000 to 3500_ yards, less than 150 yards out to five miles (10,000 yards) and on the order of 200 to 250 yards out to ten miles, the maximum range considered. This is considered to be sufficiently accurate to be of value in the solution of the local area navigation problem. Modern aircraft systems, capable of generating an inertial quality heading reference and containing a digital data processing system, are capable of overall system bearing accuracies of approximately ± 2.0 degrees. The technique of bearing averaging; i.e. , using as a bearing the mean value of a series of rapidly measured and computed bearings, upgrades the accuracy of a ± 2.0 degrees system to approximately that of the 0.50 degree system. It is therefore concluded that bearings-only fixing as an aid to local area navigation is a feasible technique for use with the latest digital aircraft systems. Recommendations are made for eventual implementation of the bearings-only technique in an operational system.