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Real Pilots Fly Adcock Ranges

A look at the navigation systems that preceded today's technology.

[Courtesy of Peter Garrison]
Gemini Sparkle

Key Takeaways:

  • Early aerial navigation relied on visual landmarks, beacon lights, and crucially, the low-frequency four-course range (LFR) system, which provided audible radio beams for pilots to follow, making instrument flying practical.
  • The LFR system, introduced in the late 1920s, guided pilots by requiring them to maintain a continuous audio tone in their headsets, a method that was complex and demanded significant pilot skill for orientation and tracking.
  • Navigation technology progressed from LFRs to hybrid Visual Aural Range (VAR) systems in the 1940s, eventually leading to the modern VOR (Very High Frequency Omni-directional Range) and GPS, dramatically simplifying and enhancing the safety of flight compared to earlier methods.
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A friend bought me an old aeronautical chart he found in a map store. Dated August 16, 1953, it covers roughly the same area as the current Los Angeles VFR [visual flight rules] terminal area chart. In the lower margin are the words: “PRICE 25 CENTS.” You got more square miles for your money then than you do today, even taking inflation into account.

The scene depicted on the chart is at once familiar and strange. Many small airports have vanished; runway diagrams of some larger ones have changed. There are only three VORs [very high frequency omni-directional range]: Long Beach, Ontario, and Palmdale. The airways are 10 statute miles wide—the FAA did not go nautical until the mid-1960s—and they are defined by what look like localizers. They aren’t localizers, however; they’re the beams of four-course ranges.

Peter Garrison

Peter Garrison taught himself to use a slide rule and tin snips, built an airplane in his backyard, and flew it to Japan. He began contributing to FLYING in 1968, and he continues to share his columns, ""Technicalities"" and ""Aftermath,"" with FLYING readers.

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