(c)
In the FLCH mode, the AFDS commands the elevators to capture and hold the selected airspeed/mode, climb/decent rate controlled by the throttle. This occurs whether in autothrottle or manual operation and is automatically limited to maximum speed limits. The FMA shows SPD as the pitch mode engaged if no limits exist. If a maximum limit exists, the FMA shows FLAP LIM or SPD LIM.
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757 MAINTENANCE MANUAL
ON/OFF SWITCH FLIGHT DIRECTOR CAPTAIN'S (KNOTS/MACH) SPEED DISPLAY DISPLAY (FT) SELECTED ALTITUDE
FIRST OFFICER'S
SELECTOR SWITCH AIRSPEED/MACH AIRSPEED/MACH MODE SELECT SWITCH/LIGHT FLIGHT LEVEL CHANGE ON/OFF SWITCH FLIGHT DIRECTOR
CONTROL KNOB AND
LOCAL MCP/REMOTE (FMC)
SPEED SELECT
SWITCH SEE A
25,000 FT
SEE B (ALT HOLD)
SEE A
10,000 FT
(ALT HOLD)
FLCH
SELECTED
FLCH SPD HDG HOLD
FLIGHT LEVEL CHANGE
. USED TO CLIMB OR DESCEND TO
AB
NEW FLIGHT LEVEL . COMBINED A/T AND FCC MODES . THROTTLES ADVANCE/RETARD TO ACHIEVE
CLIMB/DESCENT RATE BASED ON ALTITUDE CHANGE REQUESTED . IF CREW OVERRIDES THROTTLES, A/T GOES TO THROTTLE HOLD . SPEED THROUGH ELEVATOR CONTROLS SPEED TO SELECTED IAS/MACH
. AUTOMATIC TRANSITION TO VERTICAL POSITION AND A/T SPEED WHEN NEW ALTITUDE APPROACHED
Pitch Channel - Flight Level Change
Figure 13 (Sheet 1)
D01168
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757
MAINTENANCE MANUAL
CAPTAIN'S FIRST OFFICER'S
FLIGHT DIRECTOR SPEED DISPLAY SELECTED ALTITUDE FLIGHT DIRECTOR
ON/OFF SWITCH (KNOTS/MACH) DISPLAY (FT) ON/OFF SWITCH
AIRSPEED/MACH MODE SELECT SWITCH/LIGHT CONTROL KNOB AND LOCAL MCP/REMOTE (FMC) SPEED SELECT SWITCH
SELECTED
FLIGHT LEVEL CHANGE
. USED TO CLIMB OR DESCEND TO
NEW FLIGHT LEVEL . COMBINED A/T AND FCC MODES . THROTTLES ADVANCE/RETARD TO ACHIEVE
CLIMB/DESCENT RATE BASED ON ALTITUDE CHANGE REQUESTED . IF CREW OVERRIDES THROTTLES, A/T GOES TO THROTTLE HOLD . SPEED THROUGH ELEVATOR CONTROLS SPEED TO SELECTED IAS/MACH
. AUTOMATIC TRANSITION TO VERTICAL POSITION AND A/T SPEED WHEN NEW ALTITUDE APPROACHED
Pitch Channel - Flight Level Change
Figure 13 (Sheet 2)
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MAINTENANCE MANUAL
(14) Pitch Channel - Vertical Navigation (VNAV) Mode (Fig. 14)
(a) Mode Control Panel
1) The VNAV mode is active in CMD ENG or F/D ON status. It is manually requested by pressing the VNAV switch/light on the MCP. A valid VNAV request is indicated by the illumination of the dot-bar matrix on the lower half of the switch/light. The flight mode annunciator on the EADI indicates VNAV as the pitch mode engaged. The IAS/MACH speed display and the VERT SPD display are both blank when VNAV is engaged. The control source for the VNAV mode is the Flight Management Computer (FMC).
2) VNAV cannot be entered directly from glideslope arm mode. The glideslope mode is a valid submode of VNAV. The flight mode annunciator FMA on the EADI shows G/S in the pitch mode armed section.
3) A valid VNAV mode switch request is required to engage the VNAV mode (except from control inactive and G/S active).
4) The VNAV mode is armed by pressing the VNAV switch/light on the MCP. The mode is engaged for control of the vertical axis. The current vertical axis mode is disengaged when the FMC outputs valid vertical steering commands. If VNAV steering signals become NCD (no computed data) after engagement, VNAV will disengage but remain ARMED. The VNAV mode is disengaged if the A/P is disconnected (disengaged) and both F/Ds are OFF, or if any other vertical axis mode is engaged.
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