Airline Requirements for Airborne Automatic Direction Finders and the Program of Equipment Development

The convenience, ease of operation and inherent reasonableness of a direction finding system which culminates in a simple needle pointing to the selected radio station must make it seem to the late-comer that things were always thus in the plane's front office. Not so. Much anguish was experienced, many brains overtaxed, and considerable ingenuity exercised to place this apparently simple device in the hands of the pilot. It will be the purpose of this paper to give the history of the development of the Automatic Direction Finder, to give a condensed explanation of its mode of operation, and to describe its use in the navigation of aircraft.