Now, here's the problem the system is designed to solve — Page 434, Lesson 535

I want to walk you through the Flight Warning System — this is the chapter where we learn how the aircraft talks to you when something is wrong. Let's start with the big picture. The purpose of the Flight Warning System, which we abbreviate as FWS, is to produce cautions and warnings for the crew. Why? To increase your situation awareness, and to give you suitable indications of the action necessary to avoid impending danger. So it's not just about telling you something is wrong — it's about telling you what to do about it, in time to avoid the danger. Now, here's the problem the system is designed to solve. Modern aircraft have a proliferation of warning systems — lots of different things can go off. If they all went off at once, the crew could be confused by the multiplicity of warnings. So we need an integrated flight warning system — one that prioritizes the warnings. It does this by producing warnings relevant to a particular stage of flight, and inhibiting other warnings. That way, the crew can respond to the warning posing the most immediate threat to safety. So the system is actively filtering — it's deciding what matters right now and suppressing what doesn't. Let's look at the levels of alerts. The alerting and warning system produces three levels. First, Warnings, or Level A alerts. These require immediate crew action. Warnings must attract the pilot's attention in sufficient time for appropriate action to be taken. So this is the highest priority — you act now. Second, Cautions, or Level B alerts. These require immediate crew alertness and subsequent crew action. Notice the difference — with a caution, you need to be alert immediately, but the action comes subsequently, not instantly. Third, Advisories, or Level C alerts. These require crew alertness only. No immediate action, just awareness. Now let's talk about how these alerts are presented to you. The alerting and warning messages come in three forms: visual, aural, and sensory — and sensory means tactile, so things you feel, like a stick shaker. Let's focus on the visual form, because that's where the colour coding lives. The level of alert is indicated by colours. Warnings are presented in red. Cautions are shown in amber or yellow. Advisories are any colour except red or green — and on EICAS panels, they are also amber. So remember: red is the top priority, amber or yellow is the middle, and advisories are everything else, with that EICAS exception. Now, these visual indications can be presented in two different forms. The first is electronic screens. Alerts and warnings appear in coloured text or symbols on various electronic screens — that includes flight, navigation, engine, and aircraft system displays. The second form is lights or flags. Red lights or reflective flags signify warnings, and they require remedial action if flight is to continue. So if you see a red light or flag, you must take corrective action or you can't keep flying. An amber light or flag is used to indicate that a system or equipment is approaching a limit of normal function — and that corrective action is necessary to prevent further deterioration and consequent failure. So amber is the "getting close to the edge" warning — fix it before it breaks. And finally, there's one more piece of the visual picture. Master warning and caution lights are normally provided, and they're located near the centre of scan in front of each pilot. So right in your primary field of view, you have these master lights that grab your attention. That's the foundation of the Flight Warning System — the purpose, the three levels of alerts, and how they're presented visually. Next we'll get into the components of the FWS itself.