Then comes the practical flying part — Page 80, Lesson 72

This is the start of Chapter 7, the Automatic Direction Finder — the ADF. This is a big one, and it's the first time we really get into how a ground-based radio beacon can steer you through the sky. Let me give you the lay of the land first, because this chapter is structured like a flight plan. We open with an introduction, then we meet the ground station itself — the Non-directional Beacon, or NDB. That's the thing on the ground broadcasting the signal. From there we go into the principle of operation — how the aircraft actually senses that signal and turns it into a bearing. Then we cover the frequencies and the different types of NDB, the aircraft equipment you'll have in the cockpit, and something called the emission characteristics and the Beat Frequency Oscillator — the BFO, which I'll explain properly when we get there. Then comes the practical flying part. We look at how the information is presented to you, the uses of the NDB, and then the meat of it: plotting ADF bearings, track maintenance using the RBI — that's the Radio Magnetic Indicator — homing, tracking inbound, tracking outbound, drift assessment and regaining track both inbound and outbound, holding, and runway instrument approach procedures. After all that flying technique, we get into the science of errors: factors affecting ADF accuracy, factors affecting ADF range, and then a final accuracy section and an ADF summary. The chapter closes with practice questions and answers. So the whole arc is: what the beacon is, how your aircraft reads it, how you fly with it, and where it can let you down. We'll take it in that order, starting with the NDB itself. Ready when you are.