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

Let's start with the expanded VOR mode, because it's the richest display and everything else builds on it. I want you to picture the screen as a map centred on the aircraft, with a compass rose around it. Look at the top of the display. You'll see "HDG" — that's the heading readout, and it shows 130°(M), meaning the aircraft's magnetic heading is 130 degrees. Next to it, you'll see the wind readout: 126°(M)/20 kt. That's the wind direction, 126 degrees magnetic, at a speed of 20 knots. Now, the key part — the VOR information. The display tells you VOR2 is in use, on a frequency of 116.80 MHz. The aircraft is outbound from the beacon, meaning it's flying away from the VOR, at a range of 13.3 NM, which comes from the DME. The DME readout shows 13.3. Here's the navigation geometry. The required track is 165°(M) — that's the track the pilot wants to fly. The present track is 133°(M) — that's the track the aircraft is actually on. The aircraft is 7.5° right of the required track. So the deviation scale shows the aircraft is 7.5 degrees to the right of where it should be. The pilot has selected the heading bug to 104°(M). That's the little marker on the compass rose that shows the desired heading. The heading bug is set to 104 degrees magnetic. Now, the weather radar. "WXR" is selected, and the radar is in WX+T mode — that's weather plus turbulence. The radar has a 12° uptilt, meaning the antenna is tilted up 12 degrees. The display is showing a contouring cloud centred on 105°(M), between 8 and 17 NM. So there's a weather cell at bearing 105 degrees magnetic, ranging from 8 to 17 nautical miles out. The selected scale is 20 NM — that's the range scale of the display. And the wind is 126°(M)/20 kt, which we already covered. Now, the TO/FROM indication. You'll see "FROM" on the display, which tells you the aircraft is outbound from the beacon — flying away from it. That matches the "outbound" description. Let me show you the display layout. Now, the full rose VOR mode. This shows the same information as the expanded VOR mode, but with some differences in symbology. The key difference is the TO/FROM indication — instead of a text label, it's a pointer that appears either above or below the lateral deviation scale. So the full rose mode uses a pointer for TO/FROM, while the expanded mode uses the text "FROM" or "TO". Now, the expanded ILS mode. This shows the appropriate ILS information when an ILS localizer frequency is selected. 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. So if you're flying at an angle greater than 90 degrees from the localizer course, the glide slope display is blanked — it won't show you glide slope information until you're within 90 degrees of the localizer course. The full rose ILS mode shows the same information as the expanded ILS mode, and it has the same differences from the expanded ILS mode as noted for the VOR modes — meaning the TO/FROM pointer appears above or below the lateral deviation scale. But there's one important difference: the localizer deviation scale is doubled. So in the full rose ILS mode, the localizer deviation scale is twice as sensitive as in the expanded ILS mode. Let me show you the full EFIS display. So to summarise the key points: the expanded VOR mode shows VOR information with a selected VOR and either a manual or database-generated input of track. The full rose modes use a pointer for TO/FROM instead of text. The expanded ILS mode suppresses glide slope when track is more than 90° from the localizer course. And the full rose ILS mode doubles the localizer deviation scale. That's the core of the EFIS display modes.