Major components of an FDS include an ADI, also called  a Flight Director Indicator (FDI), an HSI, a mode selector,  and a flight director computer. It should be noted that a flight  director in use does not infer the aircraft is being manipulated  by the autopilot (coupled), but is providing steering  commands that the pilot (or the autopilot, if coupled) follows.  Typical flight directors use one of two display systems for  steerage. The first is a set of command bars, one horizontal  and one vertical. The command bars in this configuration  are maintained in a centered position (much like a centered  glideslope). The second uses a miniature aircraft aligned to  a command cue.  One of the first widely used flight directors was developed  by Sperry and was called the Sperry Three Axis Attitude  Reference System (STARS). Developed in the 1960s, it was  commonly found on both commercial and business aircraft  alike. STARS (with a modification) and successive flight  directors were integrated with the autopilots and aircraft  providing a fully integrated flight system.  The flight director/autopilot system described below is  typical of installations in many general aviation aircraft.  The components of a typical flight director include the mode  controller, ADI, HSI, and annunciator panel. These units are  illustrated in  Figure 5-40 . The pilot may choose from among many modes including  the HDG (heading) mode, the VOR/LOC (localizer tracking)  mode, or the AUTO Approach (APP) or G/S (automatic  capture and tracking of instrument landing system (ILS)  localizers and glidepath) mode. The auto mode has a fully  Figure 3-40 Integrated flight system.  automatic pitch selection computer that takes into account  aircraft performance and wind conditions, and operates once  the pilot has reached the ILS glideslope. More sophisticated  systems allow more flight director modes.  A flight director displays steerage commands to the pilot on  the ADI. As previously mentioned, the flight director receives  its signals from one of various sources and provides that to the  ADI for steerage commands. The mode controller provides  signals through the ADI to drive the steering bars, e.g., the  pilot flies the aircraft to place the delta symbol in the V of the  steering bars. “Command” indicators tell the pilot in which  direction and how much to change aircraft attitude to achieve  the desired result.  The computed command indications relieve the pilot of  many of the mental calculations required for instrument  flight. The yellow cue in the ADI  [Figure 5-39]  provides all  steering commands to the pilot. It is driven by a computer that  receives information from the navigation systems, the ADC,  AHRS, and other sources of data. The computer processes this  information, providing the pilot with a single cue to follow.  Following the cue provides the pilot with the necessary three- dimensional flight trajectory to maintain the desired path.  XPDR 5537 IDNT LCL 23:00:34 VOR1 270 ° 2 1 1 2 4300 4200 4100 3900 3900 3800 4300 3600 3500 3400 3300 3200 3100 20 80 4000 4000 130 120 110 90 80 70 1 100 9 TAS 100KT OAT 7°C NAV1108.00 113.00 NAV2108.00 110.60 134.000 118.000 COM1 123.800 118.000 COM2 $_{WPT }$______$_{ DIS }$__._ $_{NMDTK }$___$_{°TTRK 360°T}$ TRAFFIC  TRAFFIC  Figure 5-39. A typical cue that a pilot would follow. Figure 5-40. Components of a typical FDS. G S HDG  NA V 33 30 24 2I I5 I2 6 3 5-24