Aspen Primary Flight Display - Langley Flying School

2.3.4.1. Direction Indicator (Magnetic Compass)
The center of the Navigation Display is the Direction Indicator, or Magnetic Compass.
The compass always shows the current magnetic heading of the aircraft, both with a
numerical value of the current heading at the top of the display, and with a lubber line,
or pointer, to that heading on either a full or partial compass rose. This slaved compass
system compensates both for the turning and acceleration errors exhibited by wet
compasses and for precession errors found in common Directional Gyros, so the pilot
does not need to make adjustments to the heading indicator during the flight.
The Direction Indicators of both the Pilot and Pro PFDs share many common features,
explained below, while the Pro PFD adds features for instrument navigation. The Pilot
PFD Direction Indicator is a slaved Directional Gyro (DG) with Heading Bug. The Pro
PFD Direction Indicator adds capabilities to make it an electronic Horizontal Situation
Indicator (HSI) with dual Bearing Pointers. The HSI features are explained in a separate
section below.
Compass Modes: 360º vs. ARC
The Direction Indicator on the EFD1000 can be presented in either a full 360º compass
rose mode (shown in Figure 2-36), or in a 100º ARC format (Figure 2-37). In 360 Mode,
the compass resembles the mechanical instrument, with the ownship position in the
center of the display. ARC Mode provides an extended forward view with the ownship
position at the bottom of the display. The ARC mode is especially good for map displays.
The middle Hot Key is used to toggle the display between 360 and ARC modes, with
the current mode shown in green adjacent to the Hot Key.
Figure 2-36
360° Mode
Figure 2-37
ARC CDI Mode with
Base Map
CHAPTER 2 CONTROLS AND DISPLAY
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EFD1000 PFD Pilot’s Guide Page 2-31