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Primary Flight Display (PFD) (Part Two)

in Electronic Flight Instruments

PFDs and multi-function displays (MFDs) typically combine several navigation instruments into a single presentation. The instrument appearing at the bottom of the PFD in Figure 2-1 contains two navigation indicators: a course deviation indicator and a bearing pointer. These instruments can be displayed in a variety of views, and can be coupled to many of the navigation receivers (e.g., instrument landing system (ILS), global positioning system (GPS), very high frequency (VHF) omnidirectional range (VOR)) available in the aircraft. The pilot must, therefore, be sure to maintain an awareness of which navigation receivers are coupled to each navigation indicator.

Figure 2-1. A typical primary flight display (PFD).

Figure 2-1. A typical primary flight display (PFD). [click image to enlarge]

MFDs may provide the same type of display as installed in the PFD position, but are usually programmed to display just the navigation information with traffic, systems data, radar Stormscope®/ Strikefinder®. However, in many systems, the MFD can be selected to repeat the information presented on the PFD, thereby becoming the standby PFD. The pilot should be absolutely certain of and proficient with the standby modes of operation.

More sophisticated PFDs present three-dimensional (3D) course indications. The primary flight display in Figure 2-4 shows a 3D course indication, called a highway-in-the-sky (HITS) display. This display provides both lateral and vertical guidance along the planned flight path, while simultaneously presenting a 3D picture of the surrounding terrain. Keeping the symbolic aircraft within the green boxes on the display ensures that the flight remains within the selected GPS route and altitude. Consult the AFM and avionics manual for required navigational configuration for this function to be available.

Figure 2-4. An attitude indicator with HITS display symbology.

Figure 2-4. An attitude indicator with HITS display symbology.

Other Flight Status Information

An important feature of the PFD is its ability to gather information from other aircraft systems and present it to the pilot in the integrated display. For example, the PFD in Figure 2-5 presents many useful items about the status of the flight. The top bar shows the next waypoint in the planned flight route, the distance and bearing to the waypoint, and the current ground track. The outside air temperature (OAT) is shown in the lower left corner of the display. The transponder code and status are shown with the current time in the lower right corner. This PFD also allows the pilot to tune and identify communication and navigation radio frequencies at the top of the display.

Figure 2-5. PFD flight status items.

Figure 2-5. PFD flight status items. [click image to enlarge]

Making Entries on the PFD

PFDs have evolved and have become more than flight displays in many cases. The amount of data available for display can overwhelm the pilot with data. Therefore, many manufacturers have integrated data control and display controls into the display unit itself, usually around the perimeter of the unit. These data and display controls provide different ways of selecting necessary information, such as altimeter settings, radials, and courses. Figure 2-6 illustrates two different kinds of controls for making entries on primary flight displays. Some PFDs utilize a single knob and button-selectable windows to determine which entry is to be made. Other PFDs offer dedicated knobs for making entries; quantities are sometimes entered in one location and displayed in another. Still other units retain all controls on a separate control panel in the console or on the instrument panel.

Figure 2-6. Making entries on a PFD.

Figure 2-6. Making entries on a PFD. [click image to enlarge]


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