(a)  
The MCP has eight pushbuttons for manual selection of the following AFDS modes: 1) Vertical speed - V/S 2) Altitude Hold - ALT HLD 3) Vertical Navigation - VNAV 4) Flight Level Change - FLCH 5) Heading Hold - HDG HLD 6) Lateral Navigation - LNAV 7) Localizer - LOC 8) Approach - APP

 (b)  
Each pushbutton operates switch contacts that interface with all three FCCs. Dot-bar illumination is controlled by FCC logic.

 (c)  
A pushbutton switch labeled SEL, allows manual selection of either airspeed or mach for FLCH (flight level change) or A/T SPD (speed) modes. Switch contacts interface with the FCCs and the TMC.

 (d)  
GUN 001-050, 052-999; a pushbutton switch/light is provided for manual selection of backcourse (B/CRS). Switch contacts interface with the FCCs, and dot-bar illumination is controlled by FCC generated logic.

 (e)  
The HDG SEL (heading select) inner knob assembly contains a push action switch for manual selection of the HDG SEL (heading select) mode. The switch contacts interface with the FCCs.

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757
MAINTENANCE MANUAL

 (7)  
Heading Reference Display and Control

 (a)  
The heading reference portion of the MCP consists of a magnetic wheel heading display window and a rotary control with two concentric knobs. The display window is capable of showing 000 to 359 degrees in increments of one degree. The display is initialized to 000 when power is first applied to the MCP. At LOC capture, the display is initialized to the selected runway heading from the FCC.

 (b)  
GUN 001-050, 052-999; the outer knob of the rotary control has six positions for selection of bank angle limits (5, 10, 15, 20, 25, AUTO). The knob position is digitally transmitted to the FCCs. The inner knob increments the heading display when rotated. This heading reference is optically sensed to drive the decoders and then digitally transmitted to the FCCs.

 (c)  
GUN 051; the outer knob of the rotary control has two positions for selection of bank angle limits (NORM and 30). The knob position is digitally transmitted to the FCCs. The inner knob increments the heading display when rotated. This heading reference is optically sensed to drive the decoders and then digitally transmitted to the FCCs.

 (8)  
Vertical Speed Reference Display and Control

 (a)  
The vertical speed (V/S) portion of the MCP consists of a magnetic wheel display window and a thumbwheel control. The display window displays V/S from +6000 to -8000 ft/min in 100 ft/min increments. When V/S mode is not selected, the display shows zero. With V/S active, the display will show the vertical speed at the time the mode was selected. (If V/S is zero ft/min, A/P goes into an altitude hold control while in V/S mode). The V/S reference value is optically sensed to drive the decoders and then digitally transmitted to the FCCs.

 (b)  
The thumbwheel is used to select a given vertical speed. Upward rotation of the thumbwheel decreases the selected value, downward rotation increases it.

 (9)  
Altitude Reference Display and Control

 (a)  The altitude select portion of the MCP consists of a display window and a rotary select knob. The display can show 0 to 50,000 feet in increments of 100 feet. When power is applied to the MCP, the altitude window is set to 10,000 feet. The rotary knob increments the display when rotated (clockwise increases value). The altitude reference is digitally transmitted to the FCCs, the FMCs, and the warning electronics module.

 (10)
 IAS/MACH Reference Display and Control

 (a)  The indicated airspeed (IAS) reference section of the MCP consists of a rotary knob with an integral pushbutton switch and an IAS/MACH display window. Display limits are 100 to 399 knots in increments of one knot, and 0.40 to 0.95 Mach in increments of 0.01 Mach.
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