It is now more than thirteen years since experimental work first started in Australia on controlled height/distance paths using radar distance and barometric height. At that time, however, the effectiveness of such a system was limited since no suitable altimeter with an electrical output existed, and since the number of radio beacons in existence was much smaller than at present. With the advent of more suitable altimeters, and now that distance measuring equipment (DME) is mandatory for all passenger carrying aircraft in Australia, work has been resumed and further trials have recently been carried out.