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A
757
MAINTENANCE MANUAL

HEADING
A/P ENGAGE
A/T ARM IAS/MACH HDGVERT SPD ALT LNAVA/P COMMAND
L C R  DISPLAY
SWITCH/LIGHT
L NAV
ENGAGE SWITCHES
CMD CMD CMDF/D OFF
F/D
ON

ON
SEL 5 A/P ENGAGE
25
V NAV A/T ARM IAS/MACH HDG VERT SPDALT
CWS CWS CWSDN
LOC
LIMIT

LCR
BANK
SEL
AUTO L NAV
CMD F/DOFF
OFF
OFF
CMD
F/D FL CH HOLD
V/S HOLD APP  ON
ON
UP SEL
DISENGAGE
NORM 30
SEL V NAV UP
LOC LIMITBANK OFF OFF
OFF
OFF
1
HEADING HOLD
V/S HOLDAPP
HOLD
FL CH
L NAV LOCALIZER APPROACH
DN
SWITCH/LIGHT

SWITCH/LIGHT SWITCH/LIGHT SWITCH/LIGHT
2
LOCALIZER
HEADING HOLD APPROACHSWITCH/LIGHT SWITCH/LIGHT
SWITCH/LIGHTTHRUSTLEVERS
AIRPLANE ON FINAL ILS  _______________________
_____________________ AIRPLANE ESTABLISHED ON
GO-AROUND
SWITCHES APPROACH BEFORE GO-AROUND SELECT _____________________

________________________________ GO-AROUND FLIGHT PATH
. PREREQUISITES FOR GA ENABLE . FMA SHOWS GA FOR ROLLGSENG+FLAPS>1& PITCH ENGAGED MODES
FWD . FMA SHOWS ROLLOUT AS ROLL . GA MODE RETAINED UNTIL
ARM MODE AS THIS IS THE NEXT
CANCELLED BY SELECTION
5 NORMAL MODE  OF A CONFLICTING PITCH
400
GLIDE SLOPE

300
OR ROLL MODE
CENTERLINE

SEE A
A CGO-AROUND MODE CANCELLED BYSELECTION OF
SEE C
F/D ON OR OFF
LOC

SEE B ALT SELECT MODE
CENTERLINE

ALT HOLD MODE
FL CH MODESEE D
VNAV OR LNAV MODEHDG HOLD OR HDG SELECT MODEV/S MODESYS OFF
GO-AROUND MODE CANCELLATIONGO-AROUND MODE SELECT
_____________________ . ENABLED WHEN HR>500 FT & CLIMBING
. HAS SPLIT AXIS EFFECTIVITY
. INITIATED BY PRESSING GO-AROUND . IF AN ALTERNATE ROLL MODE IS SELECTED,
SWITCH(ES)PITCH AXIS REMAINS IN GA MODE
. APPROACH MODE CANCELLED. IF AN ALTERNATE PITCH MODE IS SELECTED,
. ROLL ENGAGED MODE ANNUNCIATED AS GA ROLL AXIS REMAINS IN GA MODE
. NO ROLL ARMED MODE ANNUNCIATION . FMA INDICATES SPLIT AXIS MODES
. GA THRUST, GA PITCH UP & ROLL CMDS FOR
TRACK HOLD GENERATED
D
. AFDS STATUS REMAINS SAME AS AT GA SELECT
. F/D CUE SHOWS ON THE EADI WITH THE F/D
SWITCH IN ON OR OFF POSITION FOR A
CHANNEL NOT CMD ENGAGED

1
GUN 001-050,052-999
B
2 GUN 052
Roll Go-Around Mode
Figure 18

EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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757
MAINTENANCE MANUAL

 4)  Position D shows the G/A cancellation conditions. Cancellation is enabled when radio altitude is greater than 400 feet and the airplane is climbing. This produces a split axis condition. If an alternate roll mode is selected, the pitch axis remains in G/A mode and vice versa. The EADI FMA indicates split axis modes. Go-around can be cancelled by selection of F/D ON or OFF; altitude select or altitude hold; FLCH; VNAV or LNAV; HDG hold or select; V/S; or system OFF.
 (26)
 Go-Around Mode Logic

 (a)  Go-around engage logic is generated by pressing the go-around switch on the thrust levers (Fig. 18). Go-around engage logic generates track mode select logic and go-around runway logic. After a one-frame delay, heading hold is generated. If the A/P is still CMD ENG, heading/track control and heading proportional command/track mode reference are generated.

 (27)
 Go-Around Mode Signal Processing

 (a)  
At go-around engage, the heading reference is synchronized to the adjusted runway heading which is compensated for drift angle (Fig. 11). The delta heading command from the A/P turn direction control is supplied to the roll F/D command processor. It is also used to generate the delta roll command. This is further processed to generate delta wheel command to the ALCS.

 (b)  
Track mode select logic selects adjusted track as input to the F/D turn direction control. The F/D heading command changes slightly to generate roll commands reflecting this change of reference from heading to track. The A/P turn direction control also senses this change in reference. The delta heading command then becomes runway heading minus adjusted track in degrees roll. This output is then processed and waits until heading track control logic is generated one frame later.
　
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