ROLL AXIS COMMANDS WINGS LEVEL UNTIL LIFT OFF,
F/D ON)
THEN GROUND TRACK HOLD
MANUALLY SELECTED (GO-AROUND SWITCHES)
MANUALLY SELECTED ON MCP
BASIC PITCH MODE ON AUTOPILOT ENGAGEMENT
AUTOMATICALLY OR MANUALLY (MCP) SELECTED PITCH AXIS COMMANDS FORWARD ACCELERATION AND POSITIVE RATE OF CLIMB USING SPEED SCHEDULE BASED ON FLAP POSITION
ROLL AXIS COMMANDS INITIAL GA GROUND TRACK HOLD
EFFECTIVE ONLY AFTER LOC CAPTURE
ROLL AXIS COMMANDS BCRS LOC CENTERLINE HOLD
COMMANDS TO ACQUIRE AND HOLD SELECTED V/S
PITCH ATTITUDE TO ACQUIRE AND MAINTAIN
SELECTED AIRSPEED OR MACH
COMMANDS TO ACQUIRE AND MAINTAIN SELECTED ALTITUDE AT SELECTED SPEED MANUALLY SELECTED ON MCP
PROVIDES FLAP PLACARD AND MIN SPEED LIMIT PROTECTION
RESPONDS TO VERTICAL STEERING COMMANDSMANUALLY SELECTED ON MCP FROM FMC
MANUALLY SELECTED ON MCP COMMANDS TO ACQUIRE AND TRACK G/S BEAM
AUTOMATICALLY CAPTURES PRESELECTED ALTITUDEAUTOMATICALLY AND MANUALLY ALTITUDE MODE HOLD ALTITUDE DISPLAYED ON MCP ALT SELECTSELECTED ON MCP (HOLD) ACTIVE WINDOW IF HOLD NOT PUSHED
(ALT SEL/HOLD) HOLDS ALTITUDE AT TIME HOLD PUSHED
SIMULTANEOUS PITCH AND ROLL MODES
GUN 001-050,052-999
Pitch Mode Functions
Figure 7
D00795
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757 MAINTENANCE MANUAL
1) The backcourse mode is selected with the B/CRS switch/light. If not within localizer capture range, the B/CRS switch reverses only the localizer displays on the ADIs. The standby attitude/ILS indicator also has a B/CRS selector which is used during a back course approach, however, it has no interconnect with the AFDS.
2) After localizer capture, the A/P or F/D provides commands to track the airplane to the back course centerline. The pitch channel continues to provide guidance from the selected pitch mode.
Vertical Speed
1) Vertical speed is the basic pitch axis mode. When the V/S switch/light is pressed with the A/P in CMD or the F/D on, the vertical speed command acquires the selected vertical speed. The existing V/S mode is automatically acquired when the F/D is initially turned on or the F/D is overridden by engaging the A/P in CMD.
Flight Level Change
1) The flight level change mode is manually selected by pressing the FLCH switch/light on the MCP. The mode uses software programmed elevator control laws to generate pitch attitude A/P or F/D commands. The pitch attitude commands control the airplane to obtain and maintain an MCP selected altitude using the MCP selected airspeed or Mach. The FLCH mode provides flap placard and minimum speed limit protection. When limits are encountered, corresponding annunciation is provided on the EADI.
Vertical Navigation Mode
1) The mode is manually selected by pressing the VNAV switch/light on the MCP. The A/P or F/D responds to pitch steering commands from the FMC. Pitch steering commands are generated in the FMC as necessary to acquire and track a vertical path along a preplanned flight route.
Glideslope Active Mode (Approach)
1) The mode is manually selected by pressing the APP switch/light on the MCP. Pitch commands are generated for A/P or F/D control to acquire and maintain capture of the glideslope. The A/P channels can be used for single channel or multi-channel ILS approaches.
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(i) Autoland Mode
1) The autoland mode is only active during multi-channel operation. Pitch commands provide flare and nose gear letdown during rollout.
(3) Output Signal Synchronization (Fig. 8)
(a) Elevator Servo Command
1) Servo command signals are synchronized to the position of the servo to prevent transients upon engagement. Elevator surface position is summed with the elevator command output which is initially at zero. Assuming the elevator is displaced, the increase in elevator position LVDT output is integrated and limited to +10 and -28 degrees of elevator displacement. The resulting output is summed at the integrator until LVDT input is nulled.
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