Electronic Instrumentation — Page 552, Lesson 660

I want to walk you through the ECAM control panel — the Electronic Centralized Aircraft Monitoring system. This is the panel that lets the crew manage what appears on the display units. Let's start with the switches, because each one has a very specific job. First, the CLR Switch — that's the "Clear" switch. Its light is illuminated white whenever a warning or status message is displayed on the left-hand display unit. So the white light tells you something is currently being shown. You press the switch to clear those messages off the display. Next, the STS Switch — the "Status" switch. This one permits manual selection of an aircraft status message, but only if no warning is currently displayed. Its light is also illuminated white. Here's a key detail: pressing the STS switch also causes the CLR switch light to illuminate. And there's a limitation — a status message is suppressed if a warning occurs, or if the CLR switch is pressed. So status messages are lower priority; a warning will push them out. Then the RCL Switch — the "Recall" switch. This enables previously cleared warning messages to be recalled, but only provided the failure conditions which initiated them still exist. That's an important qualifier — you can't recall a warning if the underlying failure has gone away. Pressing the RCL switch also causes the CLR switch light to illuminate. And here's the failure case: if a failure no longer exists, the message "NO WARNING PRESENT" is displayed on the left-hand display unit. Now, there's a note about a compact message appearing on the upper display unit when the status button is pressed on the control panel — that's the STS switch we just covered. Let me also clarify how the ECAM system is structured, because the practice questions test this. With an Electronic Centralized Aircraft Monitoring type of system, the left display unit shows warning and corrective action in a check list format. That's the key point — the left unit is your checklist for what to do. The right or lower unit shows the synoptic format — that's the system diagram. So the left is corrective action, the right or lower is the synoptic picture. Now, the Engine Indicating and Crew Alerting System — EICAS — alert messages are shown on the upper display unit in three forms, and these are levels. Level 'C' are warnings that require immediate corrective action. Level 'A' are cautions that require immediate crew awareness and possible action. Level 'B' are advisories requiring crew awareness. And these messages appear on the top left of the upper display unit. So to tie it together: the ECAM control panel has three switches — CLR to clear, STS to select status, RCL to recall warnings. The display units have specific roles — left for checklist/corrective action, right or lower for synoptic. And EICAS alerts come in three levels — A, B, C — with C being the most urgent, and they appear top-left on the upper display. These are the book's practice questions — let's try them one at a time.