777 AIRCRAFT MAINTENANCE MANUAL
AFDS -OPERATION -PITCH INTRODUCTION
EFFECTIVITY BEJ ALL 22-11-00
Page 79
D633W101-BEJ Sep 05/2002
AFDS -OPERATION -VNAV
General
Push the VNAV mode select switch to arm VNAV. The PFD shows VNAV in white and the switch LED is on. Push the switch again to remove the arm status.
VNAV can arm before takeoff. Also VNAV can arm in flight with the glideslope mode not active.
When active, VNAV on the PFD changes to green. This occurs when all these conditions are true:
*
VNAV flight plan is active
*
The airplane is greater than 400 feet above the ground
*
Data required to calculate the vertical guidance command is valid.
VNAV active has these three sub-modes:
*
VNAV SPD (speed)
*
VNAV PTH (path)
*
VNAV ALT (altitude).
VNAV SPD
The VNAV SPD mode controls the elevator to hold the FMCF target speed. The mode is active in:
*
Climb
*
Cruise or descent when the airplane exceeds an FMCF target speed by 5 knots.
VNAV PTH
In climb, VNAV SPD changes to VNAV PTH to capture the FMCF target altitude. In the VNAV PTH mode, the airplane holds the FMCF altitude.
Before descent, the pilot sets an approach altitude on the MCP. At the top of descent, the throttle retards and the autothrottle mode is IDLE. The pitch mode stays in VNAV PTH and the airplane descends. The FMC top of descent point determines descent angle and airspeed during descent.
The VNAV PTH mode continues in descent until the airplane is near the approach altitude. The autothrottle mode returns to SPD. VNAV PTH stays active and holds the approach altitude.
VNAV ALT
The VNAV ALT (altitude) mode occurs when one of these conditions is true:
*
When in VNAV SPD and the airplane captures the MCP selected altitude before the FMCF target altitude
*
When in VNAV PTH (descent) and the airplane captures the MCP altitude before the FMCF altitude.
EFFECTIVITY BEJ ALL 22-11-00
Page 80
D633W101-BEJ Sep 05/2002
777 AIRCRAFT MAINTENANCE MANUAL
AFDS -OPERATION -VNAV
EFFECTIVITY BEJ ALL 22-11-00
Page 81
D633W101-BEJ Sep 05/2002
AFDS -OPERATION -VERTICAL SPEED/FLIGHT PATH ANGLE
General
The pilot uses the VS/FPA mode to climb or descend to the altitude set in the MCP.
This example shows FPA operation. VS mode operation is the same except for the display on the PFDs.
Climb
These occur when the pilot sets a positive FPA on the MCP and pushes the VS/FPA mode select switch:
*
FPA shows on the PFD
*
The switch LED is on
*
The airplane holds the selected FPA.
Descend
These occur when the pilot sets a negative FPA on the MCP and pushes the VS/FPA mode select switch:
*
FPA shows on the PFD
*
The switch LED is on
*
The airplane holds the selected FPA.
The AFDS mode changes from FPA to altitude hold (ALT) when the airplane reaches the altitude set on the MCP.
EFFECTIVITY BEJ ALL 22-11-00
Page 82
D633W101-BEJ Sep 05/2002
AFDS -OPERATION -VERTICAL SPEED/FLIGHT PATH ANGLE
EFFECTIVITY BEJ ALL 22-11-00
Page 83
D633W101-BEJ Sep 05/2002
AFDS -OPERATION -ALTITUDE HOLD
General * The airplane holds the altitude set on the MCP.
Altitude hold is active in any of these conditions:
*
Push the altitude hold switch on the MCP
*
Select a vertical speed (V/S) of 0000 feet per minute (FPM) in
the V/S mode
*
Capture and hold the altitude set on the MCP.
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本文链接地址：777 AMM 飞机维护手册 自动飞行 Autoflight(16)
