and other Early Radio Navigation Systems through the Mid-20th Century
We’ve all seen classic films and newsreels from the “Golden Age of Air Travel”, that nostalgic era from the 1930’s to the start of the Jet Age in the 1950’s, when passengers donned minks and fedoras and walked up airstairs to board vintage “propliners” (the DC-3, Constellation, the various Pan Am Clippers, etc.). Back then, a sense of romance in air travel was very much alive. For dramatic effect, the movies of the era often showed these planes making their way through proverbial dark and stormy nights. But how exactly did these aircraft get confidently to their destinations, decades before computers and GPS, when television was still a dream and even broadcast radio itself was barely twenty years old?
The answer was the Low Frequency Radio Range (LFR), also known as the Four-Course Radio Range, the LF/MF Radio Range or for reasons described later in this site, the “Adcock” or “A-N” Range. Pilots of the era simply called it “the Range.” This was a series of radio beacons that established the first system of electronic highways that aircraft could follow, day or night, rain or shine, from point to point. Although there were promising experiments since just before the First World War, LFR became the first reliable, widespread instrument navigation system that enabled the modern all-weather aviation industry we take for granted today. LFR was the successor to the ground-based Transcontinental Airway Beacon system set up during the 1920’s: a system of regularly spaced illuminated tower beacons that lit the way for early airmail pilots. These beacons certainly helped make night time navigation possible but they were not immune to clouds or low visibility. LFR removed these last stumbling blocks and also served as the initial radio communication network for what would become the national Air Traffic Control system.
Developed in late 1920’s, the system was the backbone of North American aviation from the 1930’s through the 1950’s until it was replaced, as is the usual case, with better technology. At its height, there were over 400 such stations in use in the Continental US, each covering the area of a small city block with their tall antennae pointed skyward. Hundreds of more stations could be found in Alaska, Canada and other parts of the world. Now defunct for decades, most of these stations no longer exist, but the remains of many are as well as their transformative impact on aviation. This website is an attempt to ensure that not only is the legacy of this system preserved and shared, but serves as a resource for those attempting to locate some of this history. Here’s what’s inside: