Electronic Flight Information System (EFIS) — Page 298, Lesson 291

Let’s start with the big picture. The Electronic Flight Information System, or EFIS, is the glass-cockpit display system that replaces the old mechanical instruments. Everything we talk about now is what you will actually see on the navigation display, the ND, in a modern airliner. I want to walk you through the symbols, the colours, and the modes, because each one is a piece of information the system is giving you about your route, your weather, and your navigation. First, the Trend Vector. This is a prediction of where the aeroplane’s directional trend will be at the end of 30, 60, and 90 second intervals. It is based on bank angle and ground speed. Here is the key detail: the number of segments shown depends on your selected range scale. When the range scale is greater than 20 NM, you get three segments. On the 20 NM scale, you get two segments. And on the 10 NM scale, you get just one segment. So the trend vector is telling you, "if I keep this bank angle, where will I be pointing in 30, 60, or 90 seconds." Next, the Active Route. The active route is displayed with continuous lines between waypoints. That is the route you are actually flying. Now, Active Route Modifications are different. When you make a change in the FMC, the Flight Management Computer, but you have not activated it yet, those modifications are shown with short dashes between waypoints. The moment you activate the change in the FMC, those short dashes are replaced by a continuous line. So the short dashes are your pending change, and the continuous line is your committed route. Then there is the Inactive Route. This is displayed with long dashes between waypoints. So you have three line styles: continuous for active, short dashes for active modifications, and long dashes for inactive routes. That is a critical distinction for interpreting the map. Now, the Vertical Pointer and Deviation Scale. This displays vertical deviation from the selected vertical profile. The pointer shows you the deviation, and it is only displayed in MAP mode during descent. The scale indicates plus or minus 400 feet of deviation. So if you are descending and you are off your vertical profile, this pointer tells you how far off you are, up to 400 feet either way. The Glide Slope Pointer and Deviation Scale are for ILS mode. In ILS mode, this displays glide slope position and deviation. So when you are on an ILS approach, this shows you where you are relative to the glide slope. Wind Speed and Direction is displayed in MAP, VOR, and ILS modes. It indicates wind speed in knots and wind direction with respect to the map display orientation and compass reference. So you see the wind arrow, and it is oriented relative to how the map is set up. The North Pointer is shown in PLAN mode. It indicates that the map background is oriented and referenced to true north. So in PLAN mode, the map is always north-up, and this pointer confirms that. Now, the Altitude Profile Point and Identifier. This is shown in MAP mode. It represents an FMC calculated point, and it is labelled on the flight plan path with specific identifiers: "T/C" for top of climb, "T/D" for top of descent, "E/D" for end of descent, and "S/C" for step climb. So these are the points where your vertical profile changes, calculated by the FMC. Weather Radar Returns and Mapping Radar Returns are shown in both G, A, R, and M modes. When you push either "WXR ON" switch, multicoloured returns are presented. The most intense regions are displayed in Red, lesser intensity in Amber, and the lowest intensity in Green. Areas of turbulence are displayed in magenta. So the colour tells you the intensity of the weather return. Range Arcs are displayed in the expanded rose VOR/ILS modes when the Weather Radar Switch is ON. In MAP mode, range arcs are displayed with or without the WXR Switch ON. So the range arcs give you distance reference, and their display depends on the mode and the weather radar switch. Finally, the Selected Heading Bug and Reference Line. This indicates the heading selected on the MCP, the Mode Control Panel. A dashed line extends from the marker to the aeroplane symbol, except in PLAN mode, for ease in tracking the marker when it is out of view. So the heading bug shows you your selected heading, and the dashed line helps you find it even when it is off-screen. And the ADF Bearing Pointers indicate relative bearing to the tuned ADF station, as received from the respective ADF radio. So this shows you where the ADF station is relative to your nose. One thing I want to stress: the letters in parentheses, like (M), (W), (C), and (G), are colour codes. (M) is magenta, (W) is white, (C) is cyan, and (G) is green. So when I say the active route is continuous lines (M), that means magenta. The active route modifications are short dashes (W), white. The inactive route is long dashes (C), cyan. And the North Pointer is (G), green. These colours are standard across the display, so you can quickly identify what you are looking at. Take a moment to look at the figure I have on screen for you, ``. It shows the EFIS display with all these elements laid out. That is your reference for how it all comes together on the actual screen.