First, let's look at the very first entries — Page 389, Lesson 384

We're starting a fresh topic here — the index of the Oxford ATPL Radio Navigation manual. This is the roadmap for the entire book, and I want to walk you through what it tells us about the structure and the key concepts we'll be covering. First, let's look at the very first entries. We have the "1:60 rule" on page 162. That's a fundamental navigation technique — it states that at 60 units of distance, one unit of offset subtends an angle of one degree. We'll use it for track error and closing angles. Then we have the RNAV family. "2D RNAV" on pages 262, 263, 264 — that's two-dimensional area navigation, meaning lateral and vertical positioning. "3D RNAV" on page 262 adds a third dimension, and "4D RNAV" on pages 262 and 267 adds time as the fourth dimension. There's also a "4D Fix" on page 316 — that's a position defined in three spatial dimensions plus time. Now, look at the numeric entries. "15 000 Pulse Pairs" on page 249 — that's a rate, likely for DME. "16 700 000" on page 234 — that's a frequency in Hertz, 16.7 MHz. "24 Bit Code" on page 234 — that's a digital code length. "27 pps" and "60 pps" on page 249 — pulses per second. "150 Pulse Pairs Per Second" on page 249 — another DME rate. These are all signal characteristics we'll decode later. The "737-800 FMS" on page 268 — that's the Flight Management System for that specific aircraft. And the squawk codes: "4096" on page 233 is the total number of transponder codes available, while "7500", "7600", and "7700" on page 233 are the emergency codes — hijack, radio failure, and emergency respectively. Moving to the A section: "A9W" on page 115 — that's a specific navigation specification. "ABAS" on page 319 — Aircraft-Based Augmentation System, a form of GPS integrity monitoring. "Absorption" on page 19 — signal energy loss in the atmosphere. "Accuracy of ADF" on page 101 — we'll quantify that error. "Achievable Ranges" on page 31 — maximum usable distances. "ACT ECON PATH DES" on page 277 — that's an FMS function, active economic path descent. "ADC" on page 261 — Air Data Computer. "ADF" on pages 85 and 285 — Automatic Direction Finder. "Aerial Feeders" on page 56 — the transmission lines between transmitter and antenna. "Aerodrome Surveillance Approach Radars" on page 201 and "Aerodrome Surveillance Radar" on page 199 — these are ground-based approach radars. "Aeronautical Stations" on page 75 — ground stations in the aeronautical mobile service. And "AFDS" — that's the Autopilot Flight Director System, which we'll see integrated with navigation. That figure on page 268 shows a VOR/DME RNAV integrated navigation system — you'll see how the FMS ties the sensors together. So this index is our map. Every one of these terms — the pulse rates, the codes, the RNAV dimensions, the radar types — we'll build up from first principles. We'll start with the basics of radio wave propagation, then move through each navigation aid, and finally into the integrated systems like the FMS. That's the journey this index lays out for us.