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Pilot's Handbook of Aeronautical Knowledge
Flight Instruments
Electronic Flight Display (EFD)

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Pilot's Handbook of Aeronautical Knowledge



Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making




Blocked static system.
Figure 7-11. Blocked static system.

Some aircraft are equipped with an alternate static source
in the flight deck. In the case of a blocked static source,
opening the alternate static source introduces static pressure
from the flight deck back into the system. Flight deck static
pressure is lower than outside static pressure. Check the
aircraft AOM/POH for airspeed corrections when utilizing
alternate static pressure.

Electronic Flight Display (EFD)

Advances in digital displays and solid state electronic
components have been introduced into the flight decks
of general aviation (GA) aircraft. In addition to the
improvement in system reliability, which increases overall
safety, electronic flight displays (EFD) have decreased
the overall cost of equipping aircraft with state-of-the-art
instrumentation. Primary electronic instrumentation packages
are less prone to failure than their analogue counterparts. No
longer is it necessary for aircraft designers to create cluttered
panel layouts in order to accommodate all necessary flight
instruments. Instead, multi-panel digital flight displays
combine all flight instruments onto a single screen which is
called a primary flight display (PFD). The traditional "six
pack" of instruments is now displayed on one liquid crystal
display (LCD) screen.

Airspeed Tape
Configured similarly to traditional panel layouts, the ASI
is located on the left side of the screen and is displayed as
a vertical speed tape. As the aircraft increases in speed, the
larger numbers descend from the top of the tape. The TAS is
displayed at the bottom of the tape through the input to the air
data computer (ADC) from the outside air temperature probe.
Airspeed markings for VX, VY, and rotation speed (VR) are
displayed for pilot reference. An additional pilot-controlled
airspeed bug is available to set at any desired reference speed.
As on traditional analogue ASIs, the electronic airspeed tape
displays the color-coded ranges for the flap operating range,
normal range, and caution range. [Figure 7-12] The number
value changes color to red when the airspeed exceeds VNE to
warn the pilot of exceeding the maximum speed limitation.

Attitude Indicator
One improvement over analogue instrumentation is the
larger attitude indicator on EFD. The artificial horizon spans
the entire width of the PFD. [Figure 7-12] This expanded
instrumentation offers better reference through all phases of
flight and all flight maneuvers. The attitude indicator receives
its information from the Attitude Heading and Reference
System (AHRS).

The altimeter is located on the right side of the PFD.
[Figure 7-12] As the altitude increases, the larger numbers
descend from the top of the display tape, with the current altitude
being displayed in the black box in the center of the display tape.
The altitude is displayed in increments of 20 feet.

Vertical Speed Indicator (VSI)
The VSI is displayed to the right of the altimeter tape and can
take the form of an arced indicator or a vertical speed tape.
[Figure 7-12] Both are equipped with a vertical speed bug.

Heading Indicator
The heading indicator is located below the artificial horizon
and is normally modeled after a Horizontal Situation
Indicator (HSI). [Figure 7-12] As in the case of the attitude
indicator, the heading indicator receives its information from
the magnetometer which feeds information to the AHRS unit
and then out to the PFD.

Turn Indicator
The turn indicator takes a slightly different form than the
traditional instrumentation. A sliding bar moves left and right
below the triangle to indicate deflection from coordinated
flight [Figure 7-12] Reference for coordinated flight comes
from accelerometers contained in the AHRS unit.

The sixth instrument normally associated with the "six pack"
package is the tachometer. This is the only instrument that is
not located on the PFD. The tachometer is normally located
on the multi-function display (MFD). In the event of a display
screen failure, it is displayed on the remaining screen with
the PFD flight instrumentation. [Figure 7-13]