Section 3 Display Symbology
1
st
Ed Nov 2018
IDU-450 EFIS Software Version 8.0H (Rotorcraft)
3-17
3.3.12. Unusual Attitude Mode
Unusual attitude mode is enabled when pitch attitude e30° or -30°
or bank angle exceeds 50° and remains engaged until pitch attitude returns
to within 5° of the horizon and bank attitude returns to within 10° of the
horizon. Recovery chevrons tied to the 30° and higher pitch scale
indications (both positive and negative) aid in unusual attitude recovery and
are a normal part of the pitch scale and are not necessarily tied to unusual
attitude mode.
Less than 30° pitch up
More than 30° pitch up
Figure 3-35: Unusual Attitude Mode
The following features are disabled in unusual attitude mode:
1) Terrain and obstruction
rendering
2) CDI
3) VDI
4) Flight path marker
5) Highway in the Sky boxes
6) Atmospheric
perspective
7) Analog and digital AGL
indication
8) Active waypoint symbology
9) Mini
map
10) Traffic thumbnail
11) If in basic mode, PFD reverts to
normal mode
12) If in zoom mode FOV, PFD
reverts to normal FOV
13) Runways
14) Menus
3.3.13. PFD Background
The PFD has a 3-D background generated from terrain elevation and
obstruction elevation data stored in electronic memory. The “actual
horizon” displayed on the PFD is based upon the higher of terrain within
90NM or a horizon calculated using a visible horizon equation. Thus, the
