Autopilot — Page 381, Lesson 463

We're starting a brand-new chapter now — Chapter 27, Autoland. And I want to set the stage properly, because this chapter builds directly on the autopilot work we just finished. The autopilot, as we saw, can form part of the overall Flight Management System — the FMS. That system may also be designated the Automatic Flight Control System, the AFCS, or the Flight Management and Guidance System, the FMGS. It provides manual or automatic modes of control throughout the entire flight envelope, from take-off to landing and roll-out. All the subsystems of the FMS are fully integrated and have levels of redundancy to achieve a high level of reliability. Redundancy is accomplished by providing two or more systems of each type, so a failure of one system will not affect the operation of the complete system. The AFCS and FMS will be checked completely during the preflight checks. During these checks, all the automated systems will be engaged, tested, and their various safety devices tested. The FMS will be checked for the correct information, and any additional information will be entered. Now, that's the foundation. Autoland is the natural extension of that philosophy — it's the system that carries that automatic control all the way through the landing itself. The chapter opens with an introduction, then moves into the Autoland System itself, then the Automatic Landing Sequence, then the Sequence in detail, then Other Features of Autoland. There's also an Appendix 3A that covers the ILS — the Instrument Landing System — plus Weather Minima, the ICAO Categorization of Low Visibility Landing Capabilities, and Alert Height. So the structure of this chapter is: first we understand what autoland is and how it's built, then we walk through the exact sequence of events during an automatic landing, then we look at the additional features that make it work, and finally we get into the operational rules — the weather minima, the ICAO categories, and the alert height concept. Let's start with the introduction. Autoland is the system that allows the aircraft to perform a landing automatically, without the pilot manually controlling the flare and touchdown. It's the ultimate expression of the autopilot's capability — taking that automatic control from cruise, through approach, and all the way to the runway. The key concept here is that autoland isn't just about the autopilot. It's about the whole integrated system — the FMS, the AFCS, the FMGS — working together with redundancy. Remember, redundancy means having two or more systems of each type, so that if one fails, the complete operation isn't affected. That's absolutely critical for autoland, because you're committing the aircraft to an automatic landing in conditions where the pilot may not be able to see the runway until very late, or possibly not at all. Now, the chapter introduction also mentions the preflight checks. The AFCS and FMS will be checked completely during preflight. All the automated systems will be engaged and tested, and their various safety devices tested. The FMS will be checked for correct information, and any additional information will be entered. This is your first line of defence — you verify the system is healthy before you ever commit to using it. So, to summarise where we are: we've set the context — autoland is part of the FMS family, it relies on redundancy, and it's checked thoroughly before flight. Now we're ready to move into the actual Autoland System itself, which is where we'll look at how the system is constructed and what components make it work. Let's continue.