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(4) ALT, VERT SPD, & HDG Reference Displays/Controls
(a) Encoders and Displays
1) Each numerical magnetic wheel display has an optical encoder. This is controlled by a knob or thumbwheel which is used for modifying the display. Each encoder has dual redundant circuits on a common shaft for interfacing with channels A and B of the MCP.
2) Each display has initial, maximum, and minimum values and an incremental value as previously defined in the component details section.
3) The V/S and HDG displays can be initialized/synchronized by the FCCs or manually set by the crew.
(5) IAS/MACH Reference Displays/Controls
(a) IAS/MACH Display States and Transitions
1) The IAS/MACH display has four valid states. a) OFF b) Airspeed being displayed: Airspeed (IAS) display is
entered automatically when MCP power is turned on or when the SPD knob is pressed. Airspeed is also displayed if the SEL switch is pressed when MACH is being displayed, or if the display is blank when SPD or FLCH modes are initiated.
c) MACH being displayed: this state is entered if the SEL switch is pressed when airspeed is being displayed and the airplane's speed is between 0.40 and 0.95 mach.
d) Speed display blank: this state is entered from either IAS or MACH display states if the VNAV mode is initiated or the SPD knob is pressed with the AFDS not in the FLCH, SPD, T/O, or G/A modes. (These are airspeed-being-displayed only modes.)
(b) Encoders and Displays
1) The numerical magnetic wheel display is modified by an optical encoder which is controlled by the rotary knob. The encoder has dual redundant circuits on a common shaft for interfacing with channels A and B of the MCP. The display shows airspeed from 100 to 399 knots in increments of one knot, and Mach number from 0.40 to 0.95 in increments of 0.01 Mach. If the reference airspeed from the FCC is invalid, the display shows 200 knots.
2) The IAS/MACH display can be initialized/synchronized by the FCCs or manually set by the crew.
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(6) GUN 001-050, 052-999;
AFDS MCP Disengage Bar - Operation
(a) The DISENGAGE bar provides total disengagement of all three FCCs. The switch assembly consists of three DPDT toggle switches (one for each FCC) tied together with a bar across the bat handles. When the bar is up, the servos may be engaged. When down, 28 Vdc is removed from the servos, preventing engagement. When the bar is down, a dayglow orange strip is visable, annunciating the disengaged position of the switch.
I. Autopilot/Flight Director System Interfaces (Fig. 4)
(1)
The integrated Flight Management Systems (FMS) consists of the L and R FMCs, the L, R, and C AFDSs, the Thrust Management System (TMS), and the Maintenance Control Display Panel (MCDP).
(a)
AIRPLANES WITH CONTROL WHEEL STEERING; the AFDS can function with the A/P off, and the F/D on; or with single channel A/P engaged in CWS or CMD with the F/D on. The configuration for autoland operation is normally three channels but can be two autopilot channels in CMD and F/D off or on.
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