Electronic Flight Information System (EFIS) — Page 287, Lesson 288

Let’s start with the big picture. The Electronic Flight Information System — EFIS — is the glass cockpit’s way of putting navigation and flight data onto a screen instead of separate mechanical instruments. What I want to walk you through now is the display modes, because the same screen can show you different kinds of information depending on what you select. The book gives us four modes: expanded VOR, full rose VOR, expanded ILS, and full rose ILS. Let’s take the expanded VOR mode first. “Expanded” means the display is opened up — you get a large, detailed picture of the VOR information. This mode is used when you have a VOR selected, and the track input can come from one of two sources: either the pilot sets it manually, or the navigation database generates it automatically. So the track you’re flying toward can be typed in by hand or pulled from the stored route. Now let’s read the actual display, because every number on that screen means something. The example shows VOR2 is in use, on a frequency of 116.80 MHz. The aircraft is outbound from the beacon — that means it’s flying away from the VOR — at a range of 13.3 nautical miles, which comes from the DME. The aircraft is 7.5° to the right of the required track, and that required track is 165° magnetic. The heading is 130° magnetic, and the present track — the actual path over the ground — is 133° magnetic. Notice heading and track are different; that’s drift. The pilot has set the heading bug to 104° magnetic, which is the little marker you can move around the compass to remind yourself of a desired heading. There’s also weather radar on this display. WXR is selected, and the radar is in WX+T mode — that’s weather plus turbulence. The radar has 12° of uptilt, meaning the antenna is tilted up 12° to scan the weather. The display is showing a contouring cloud — that’s the radar’s way of outlining the heavy precipitation — centred on 105° magnetic, between 8 and 17 nautical miles from the aircraft. The selected range scale is 20 nautical miles, so the whole screen represents 20 NM. And finally, the wind is 126° magnetic at 20 knots. So that one screen is giving you navigation, weather, and wind all at once. Now the full rose VOR mode. This shows the same information as the expanded VOR mode, but with differences in symbology — the way the symbols are drawn — and one key difference: the TO/FROM indication. In the expanded mode you get a TO or FROM flag. In the full rose mode, the TO/FROM indication is a pointer that appears either above or below the lateral deviation scale. So instead of a word, you get a pointer that tells you whether you’re flying toward or away from the station. Next, the expanded ILS mode. This one shows the appropriate ILS information when you select an ILS localizer frequency. Here’s the critical limitation: the glide slope indications are suppressed when the aircraft track is more than 90° removed from the ILS localizer course. In plain terms, if you’re flying more than 90° away from the localizer heading, the glide slope — the vertical guidance — disappears from the display. That’s because you’re too far off the approach to make sense of it. Finally, the full rose ILS mode. It shows the same information as the expanded ILS mode, and it has the same differences from the expanded mode that we noted for the VOR modes — same symbology changes, same TO/FROM pointer. But there’s one extra difference: the localizer deviation scale is doubled. That means the scale that shows how far left or right you are from the localizer centreline is twice as wide, so you get a finer, more sensitive read of your lateral position on the approach. So the pattern across all four modes: expanded gives you a big detailed picture, full rose gives you the same data with different symbols and a pointer for TO/FROM, and the ILS modes add glide slope — but only when you’re within 90° of the localizer course. The full rose ILS doubles the localizer deviation scale for extra sensitivity. That’s the whole set of display modes.