Until recently, most GA aircraft were equipped with individual instruments used collectively to safely operate and maneuver the aircraft. With the release of the electronic flight display (EFD) system, conventional instruments have been replaced by multiple liquid crystal display (LCD) screens. The first screen, in front of the left-seat pilot, is the primary flight display (PFD). The second, approximately in the center of the panel, is the multi-function display (MFD). These two screens de-clutter instrument panels while increasing safety, through the use of solid-state instruments with a failure rate far lower than conventional analog instruments. [Figure 2-18]
With today’s improvements in avionics and the introduction of EFDs, pilots at any level of experience need an astute knowledge of the onboard flight control systems, as well as an understanding of how automation melds with Aeronautical Decision-Making (ADM). These subjects are covered in detail in Chapter 17, Aeronautical Decision-Making.
Whether an aircraft has analog or digital (“glass”) instruments, the instrumentation falls into three categories: performance, control, and navigation.
2.7.1 Performance Instruments #
The performance instruments indicate the aircraft’s actual performance, determined by reference to the altimeter, airspeed or vertical speed indicator (VSI), heading indicator, and turn-and-slip indicator. Airspeed is read on the airspeed indicator, altitude on the altimeter, and climb performance on the VSI. Other performance instruments include the heading indicator, angle-of-attack indicator, and slip-skid indicator. [Figure 2-19]
2.7.2 Control Instruments #
The control instruments [Figure 2-20] display immediate attitude and power changes and are calibrated to permit adjustments in precise increments. The instrument for attitude display is the attitude indicator. The control instruments do not indicate aircraft speed or altitude; to determine those and other variables, a pilot must reference the performance instruments.
2.7.3 Navigation Instruments #
The navigation instruments indicate the position of the aircraft relative to a selected navigation facility or fix. This group includes various course indicators, range indicators, glideslope indicators, and bearing pointers. Newer, more advanced instrumentation provides blended information, giving the pilot more accurate positional information. Navigation instruments display GPS, VHF omnidirectional range (VOR), nondirectional beacon (NDB), and instrument landing system (ILS) information. They also provide pilotage information so the aircraft can be kept on a predetermined path, in two or three dimensions relative to ground-based or space-based navigation information. [Figures 2-21 and 2-22]
2.7.4 Global Positioning System (GPS) #
GPS is a satellite-based navigation system composed of a network of satellites placed into orbit by the U.S. Department of Defense (DOD). Originally intended for military applications, the system was made available for civilian use in the 1980s. GPS works in all weather, anywhere in the world, 24 hours a day. A GPS receiver must be locked onto the signal of at least three satellites to calculate a two-dimensional position (latitude and longitude) and track movement; with four or more satellites in view, it can determine a three-dimensional position (latitude, longitude, and altitude). Other satellites must also be in view to offset signal loss and ambiguity. GPS use is discussed in more detail in Chapter 15, Navigation, and in the Aeronautical Information Manual (AIM).
