Electronic Flight Information Systems — Page 55, Lesson 49

I want to walk you through the symbology and functions of an Electronic Flight Information System, or EFIS, as it appears on the navigation displays you’ll use in the cockpit. This is the start of a new topic, so let’s build it from the ground up. First, we have the Predict function. This predicts the ground track that will result from your present heading and the current winds. It’s displayed on the MAP mode. The displayed range mark for this prediction is one-half of the actual selected range. So if you have 40 NM selected, the range mark shows at 20 NM. Next, the Aeroplane Symbol. There are two versions. The first, labelled (W) for white, represents the aeroplane and indicates its position at the apex of the triangle. This is used in MAP, VOR, and ILS modes. The second version, also labelled (W), represents the aeroplane and indicates its position at the centre of the symbol. This is used in Full VOR and Full ILS modes. So the symbol changes shape and reference point depending on the display mode. The Active Waypoint is the waypoint the aircraft is currently navigating to. It’s displayed in MAP and PLAN modes, labelled (M) for magenta. An Inactive Waypoint, labelled (W) for white, represents a navigation point that makes up the selected active route but is not the current target. You’ll see an example like AMBOY on the display. The Altitude Range Arc, labelled (G) for green, is displayed on the MAP mode. When intersected with the track line, it predicts the point where the reference altitude will be reached. This helps you visualise where you’ll capture or level off at a target altitude. The Trend Vector predicts the aeroplane’s directional trend at the end of 30, 60, and 90 second intervals. It’s based on bank angle and ground speed. The number of segments displayed depends on the selected range: three segments when the selected range is greater than 30 NM, two segments on the 20 NM range, and one segment when on the 10 NM scale. Now let’s talk about route display. The Active Route, labelled (M) for magenta, is displayed with continuous lines between waypoints. This is shown in MAP and PLAN modes. When you make Active Route Modifications, labelled (W) for white, those modifications are displayed with short dashes between waypoints. When a change is activated in the FMC — the Flight Management Computer — those short dashes are replaced by a continuous line. Inactive routes, labelled (C) for cyan, are displayed with long dashes between waypoints. You’ll see examples like AMBOY, KILMR, PARBY, and ARO on the route. The Vertical Pointer and Deviation Scale, labelled (M) for magenta, displays vertical deviation from the selected vertical profile. This pointer is shown in MAP mode during descent only. The scale indicates +/- 400 feet of deviation. The Glide Slope Pointer and Deviation Scale, labelled (W) for white, displays the glide slope position and deviation in ILS mode. The Drift Angle Pointer, labelled (W) for white, displays the difference between the FMC track angle and the IRS heading. This is shown in Full VOR and Full ILS modes. Wind Speed and Direction, labelled (W) for white, indicates wind speed in knots and wind direction with respect to the map display orientation and compass reference. This is shown in MAP, VOR, and ILS modes. The Offset Path and Identifier, labelled (M) for magenta, presents a dot-dash line parallel to and offset from the active route. This appears after selection on the FMC CDU — the Control Display Unit. It’s shown in MAP and PLAN modes. The North Pointer, labelled (G) for green, indicates that the map background is orientated and referenced to true north. This is shown in PLAN mode. The Altitude Profile Point and Identifier, labelled (G) for green, represents an FMC calculated point and is labelled on the flight plan path as "T/C" for top of climb, "T/D" for top of descent, and "S/C" for step climb. This is shown in MAP mode. Finally, Weather Radar Returns and Mapping Radar Returns, labelled (G, A, R) for green, amber, and red, are presented when either the "WXR ON" switch is pushed. The most intense regions are displayed in red, lesser in amber, and the lowest intensity in green. This is shown in MAP, VOR, and ILS modes. Let’s look at the diagrams that illustrate these symbols. That covers the core symbology for the EFIS navigation display.