Altitude Hold Switch
These occur when the pilot pushes the altitude hold switch on the MCP:
*
The AFDS holds the present barometric altitude
*
The altitude hold light is on
*
The pitch flight mode annunciator on PFD shows ALT.
Set V/S To 0000 FPM
These occur when the pilot sets a vertical speed of 0000 FPM:
*
The airplane levels and holds the present barometric altitude
*
The V/S mode remains active
*
The pitch flight mode annunciator on PFD shows V/S.
Capture Altitude
Altitude capture starts as the airplane approaches the MCP selected altitude:
* The pitch flight mode annunciator on PFD shows ALT in
green
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AFDS -OPERATION -ALTITUDE HOLD
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AFDS -OPERATION -FLIGHT LEVEL CHANGE
General
The FLCH mode permits the pilot to change flight levels with the AFDS and the TMCF. The autothrottle controls thrust. The AFDS controls airspeed with the elevator.
FLCH Selection
The pilot must set a target altitude on the MCP before the FLCH mode can be set.
With the FLCH mode active, the flight level change light is on. FLCH SPD is the pitch mode and THR is the autothrottle mode on the PFDs.
If the pilot pushes the FLCH switch with VNAV as the active mode, the MCP IAS/mach window shows the FMCF target speed. The AFDS controls to this speed until the pilot sets a new speed in the window.
When TO/GA is the active pitch mode and the pilot pushes the FLCH switch, the IAS/mach window shows the higher of these:
*
Present airspeed
*
Speed set in the MCP.
If you push the FLCH switch when the IAS/mach window shows a speed or mach number and the active pitch mode is not TO/ GA, the MCP IAS/mach window does not change.
In all cases, the AFDS controls to the speed on the MCP IAS/ mach window until the pilot sets a new speed in the window.
The airplane speed stays within these limits:
*
Flap placard speeds
*
Maximum operating velocity and Mach (VMO/MMO)
*
Minimum speed.
Altitude Capture
When the airplane is at the altitude set on the MCP, the AFDS pitch mode changes to ALT. The autothrottle mode changes to SPD.
If there is not enough engine thrust to capture the altitude and hold airspeed, the AFDS stays in the speed mode and does not go to the ALT mode.
A/T Modes
These A/T modes can show during FLCH:
*
THR
*
HOLD
*
IDLE.
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AFDS -OPERATION -APPROACH/AUTOLAND INTRODUCTION
General
These AFDS functions are available for landing:
*
Localizer (LOC)
*
Glideslope (G/S)
*
Flare (FLARE)
*
Runway Alignment
*
Rollout (ROLLOUT)
*
Go-Around (TO/GA).
The flight crew pushes the APP switch on the MCP to arm the LOC and G/S modes.
Localizer
The LOC mode captures and holds the airplane to a localizer flight path.
Glideslope
The G/S mode captures and holds the airplane to a vertical descent flight path.
Flare
The flare mode controls the airplane to a smooth touchdown at a point past the glideslope antenna. This is a computed command and is not part of the glideslope mode.
Runway Alignment
In crosswind conditions, the runway alignment mode supplies roll and yaw control to decrease the airplane crab angle for touchdown. The runway alignment mode also includes roll and yaw control for an engine failure in approach during autoland.
There is no annunciation on the PFD for this mode.
Rollout
After touchdown, the rollout mode controls the airplane to the runway center line. Airplane deviation from the localizer center line supplies rudder and nose wheel steering signals.
Go-Around
The go-around mode controls roll and pitch after an aborted approach. Also, the TMCF controls thrust during go-around.
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