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

I want to walk you through the Electronic Flight Information System — EFIS — and specifically how the navigation displays present information to you. This is the system that puts the map, the ILS, the weather radar, and the flight plan all on your screens, and each symbol and line has a precise meaning you must read instantly. Let's start with the Trend Vector. This is a prediction of where your aeroplane's directional trend will be at the end of 30, 60, and 90 second intervals. It's based on your bank angle and your ground speed. Here's the key detail: the number of segments shown depends on your selected range scale. When the selected range scale is greater than 20 NM, you get three segments displayed. On the 20 NM scale, you get two segments. And when you're on the 10 NM scale, only one segment is displayed. So the trend vector is telling you, "if I keep this bank angle and this ground speed, here's where I'll be pointing in 30, 60, or 90 seconds." Next, the Active Route and how it's drawn on the map. The active route is displayed with continuous lines between waypoints — that's the solid line you follow. Now, active route modifications are displayed with short dashes between waypoints. When you activate a change in the FMC — the Flight Management Computer — those short dashes are replaced by a continuous line. So the moment you commit the change, the display updates to a solid line. Then there are inactive routes, which are displayed with long dashes between waypoints. So you have three line styles: continuous for active, short dashes for pending modifications, long dashes for inactive routes. Now the Vertical Pointer and Deviation Scale. This displays vertical deviation from your selected vertical profile — the pointer shows it — and it operates in MAP mode during descent only. The scale indicates plus or minus 400 feet of deviation. So if you're descending and you've selected a vertical profile, this pointer tells you how far above or below that profile you are, up to 400 feet either way. Let's look at the Glide Slope Pointer and Deviation Scale. This is part of the ILS — the Instrument Landing System. It displays glide slope position and deviation in ILS mode. So when you're flying an ILS approach, this shows you where you are relative to the glide slope beam. Wind Speed and Direction — this indicates wind speed in knots and wind direction with respect to the map display orientation and compass reference. So you get the wind speed in knots, and the direction is shown relative to how the map is oriented and referenced to the compass. The North Pointer — this indicates that the map background is orientated and referenced to true north. So when you see this pointer, you know the map is set up with true north at the top. Now let's move to the next set of symbols. The Altitude Profile Point and Identifier — this represents an FMC calculated point, and it's labelled on the flight plan path with specific identifiers. You'll see "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 key points along your vertical profile that the FMC has calculated for you. Weather Radar Returns and Mapping Radar Returns — these are shown in both the G, A, R, and M modes. Multicoloured returns are presented when either "WXR ON" switch is pushed. Here's the colour coding you must know: 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 red is the heaviest precipitation, amber is moderate, green is light, and magenta is turbulence. Range Arcs — these 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 rings on the display, and their presence depends on the mode and the weather radar switch position. Selected Heading Bug and Reference Line — this indicates the heading you've 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's out of view. So if you've selected a heading and the bug is off-screen, that dashed line helps you find it. Finally, the ADF Bearing Pointers — these indicate relative bearing to the tuned ADF station, as received from the respective ADF radio. So the ADF — Automatic Direction Finder — gives you the bearing to the station you've tuned, and the pointer shows that relative bearing on the display. Let me pull this together. You have a display that shows you your route with three line styles, your vertical profile with specific labelled points, your ILS glide slope, your wind, your weather radar with colour-coded intensity, your heading bug, and your ADF bearings. Each one has a specific mode it appears in and a specific meaning. The trend vector predicts where you're heading based on bank angle and ground speed, with segment count tied to your range scale. The vertical pointer works only in descent. The weather radar colours are standard — red, amber, green, magenta. And the route lines tell you whether a modification is pending or active. That's the full picture of what these EFIS symbols are telling you.