Let me start with the communications and data-link entries, since those… — Page 653, Lesson 750

This is the index of the book — the alphabetical listing of every topic inside it. So what I want to do is walk you through the entries that appear here, because they tell you exactly what this volume covers and how the chapters are organised. Let me start with the communications and data-link entries, since those cluster together. We have the Aeronautical Telecommunications Network, abbreviated ATN — that's the global digital network that carries data between aircraft and ground systems. Then ACARS, the Aircraft Communication Addressing and Reporting System — that's the classic data-link system airlines use to send messages to and from aircraft. Related to that is the Aircraft Operational Centre, the AOC, which is the airline's ground facility that manages fleet operations and communicates with its aircraft. Now, the air traffic side. We have the Air Traffic Service Unit, the ATSU — that's the ground unit providing air traffic services. And we have three distinct services listed: the Air Traffic Control Service, the Air Traffic Advisory Service, and Air Traffic Management. Notice the contrast — control service is the active separation service, advisory service is a lower level of assistance, and management is the broader coordination of traffic flow. There's also AFN, which the index expands for us: ATS Facility Notification. That's the data-link procedure where an aircraft logs in and notifies the ground facility that it's operating in that airspace. Now the flight instruments and systems. We have the Air Data Computer, the ADC — that's the computer that takes raw air pressure and temperature inputs and computes things like altitude, speed, and Mach number. It's referenced at pages 91, 97, 98, and 337. The AFCS is the Automatic Flight Control System — the autopilot and flight director system. And we have Aircraft Stabilization at page 352, which is the automatic damping and control of the aircraft's attitude. On the attitude instrument side, we have AH at page 169 — that's the Artificial Horizon, the attitude indicator. And there's a specific variant listed: the Air Driven Artificial Horizon at page 172 — that's the version powered by a vacuum or pressure source rather than electrically. Now the recording and warning systems. AIDS is the Aircraft Integrated Data Systems at page 499 — that's the system that records and monitors aircraft performance data. And we have ALERT at page 242, with an Alert annunciator — that's the warning light or indicator that alerts the crew to a fault or condition. Let me also cover the remaining entries. AGL is Above Ground Level at page 263 — that's altitude measured relative to the terrain directly below. Aircraft Installation Delay at page 267 — that's a delay in the installation of equipment. Aircraft Performance at page 25 — that's the chapter on how the aircraft performs in flight. Aircraft Systems at page 311 — that's the systems chapter. Air Temperature Thermometers at page 26 — those measure outside air temperature. Airports at page 293 — that's the chapter on airport-related instrumentation. And Air Data at page 366 — that's the air data system chapter. So this index is your map. It shows you the full scope: data-link communications, air traffic services, air data computation, flight control, attitude instruments, recording systems, and alerting. Each entry points you to the page where that topic is taught in detail.