Look at the entries here — Page 655, Lesson 763

This is the index of the book — the alphabetical listing of topics and the page numbers where they appear. I want to walk you through what this tells you, because learning to read an index is part of learning to use your training material properly. Look at the entries here. We have "DH REF," "DH RST," "DH SEL" — these are all related to Decision Height, the altitude on an approach where you must decide whether to continue or go around. DH REF is the reference, DH RST is the reset, DH SEL is the select function. You'll find those on pages 284 and 286. Then we have "Digital" — that's a broad topic spanning pages 7, 98, and 307. Under it, "Digital Computer Components (Hardware)" on page 308, and "Digital Computers" on page 307. Notice the distinction: the components are the physical parts, the hardware; the computers themselves are the whole system. We also have "Digital Flight Guidance System (DFGS)" on page 311 — that's the autopilot and flight director system working together. "Digital Read-out" on page 266, "Digital to Analogue Conversion" and "Digital to Analogue Converter" both on page 311 — that's the process of turning digital signals into analogue ones, and the device that does it. Now the compass entries: "Direct Indicating Magnetic Compass" on page 119, "Direct Reading Compass" on page 211, "Direct Reading Magnetic Compass" on page 204, and "DRMC" — that's the abbreviation for Direct Reading Magnetic Compass. These are all the simple, direct-reading compasses as opposed to gyro-stabilized ones. Then "Directional Gyro Indicator" on pages 153 and 211, and "Direction indicator (DI)" on page 153 — that's the gyroscopic instrument that shows your heading. "Directive Force" on page 112 — that's the force that aligns the compass needle with the Earth's magnetic field. "Direct Reading" on page 26 — that's a general term for instruments you read directly. We have "Displacement Gyros" on page 144 — those are gyros that measure angular displacement rather than rate. "DISPLAY" on page 278, "Display Panels" on page 239, "Display Units" on page 282 — these are the screens and panels that show you the information. "Distance and Time" on page 245, "DME" on page 291 — that's Distance Measuring Equipment, the radio system that tells you how far you are from a beacon. "DMU" on page 499 — that's likely a Data Management Unit. "Downlink" on page 318 — that's data sent from the aircraft to the ground. "Drain Holes" on page 14 — those are the small holes in instruments that let moisture escape. "Drift" on pages 141 and 256 — that's the angular difference between your heading and your track. "Drift Rate Calculations" on page 163 — that's how you compute that drift over time. So this index is your map. When you're studying, you look up a topic, and it tells you exactly where to go. That's the practical skill here — knowing that DH REF, DH RST, and DH SEL are all decision-height functions, and that DRMC is just the abbreviation for the Direct Reading Magnetic Compass.