Glide Slope Capture
On some airplanes, the glide slope capture cannot occur prior to localizer capture. The G/S can be captured from above or below. Capture occurs at 2/5 dot and results in the following:
.
G/S annunciates captured

.
previous pitch mode disengages

.
APP light extinguishes if localizer has also been captured

.
airplane pitch tracks the G/S

.
GA displayed on thrust mode display (N1 thrust limit). After VOR/LOC and G/S are both captured, the APP mode can be exited by:

.
pressing a TO/GA switch

.
retuning a VHF NAV receiver
. overriding pitch or roll into CWS (as installed).

At approximately 50 feet, RA, the F/D command bars retract. The autopilot must be manually disengaged prior to landing.
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4.20.18  December 1, 2000

Automatic Flight -System Description 737 Operations Manual
Automatic Flight Approach Profile

G/S Capture
. GA displayedon Thrust Mode Display

Copyright . The Boeing Company. See title page for details.
December 1, 2000  4.20.19
Automatic Flight -System Description 737 Operations Manual

Go–Around
Go–Around (GA) mode is engaged by pushing either TO/GA switch. An A/P go–around requires dual A/P operation and is armed when FLARE armed is annunciated. If both A/Ps are not operating, a manual F/D go–around is available.
With the A/T Arm switch at ARM, the A/T go–around mode is armed when descending below 2000 feet RA, with or without the AFDS engaged. Once armed, the A/T go–around mode can be engaged until 2 seconds have elapsed after landing touchdown.
A/P Go–Around
The A/P GA mode requires dual A/P operation and is available after FLARE armed is annunciated and prior to the A/P sensing touchdown.
With the first push of either TO/GA switch:
. 
 A/T (if armed) engages in GA and the A/T Engaged Mode annunciation
on the FMA indicates GA

.  
Thrust advances toward the reduced go–around N1 to produce 1000 to
2000 fpm rate of climb

.  
Pitch mode engages in TO/GA and the Pitch Engaged Mode annunciation
on the FMA indicates TO/GA

.  
F/D pitch commands 15 degrees nose up until reaching programmed rate
of climb. F/D pitch then commands maneuvering speed for each flap
setting based on maximum weight calculations

.  
F/D roll commands hold current ground track. The Roll Engaged Mode
annunciation on the FMA is blank

.  
The IAS/Mach display blanks

.  
The airspeed cursor displays maneuvering speed for existing flap setting
based on maximum weight calculations.

Note:  If the go–around mode is selected after touchdown and prior to A/T disengagement, the A/Ps disengage and the A/Ts may command GA thrust.
With the second push of either TO/GA switch after A/T reaches reduced go–around thrust, the A/T advances to the full go–around N1 limit.
TO/GA mode termination from A/P go–around:
.  
Below 400 feet RA, the AFDS remains in the go–around mode unless
both A/Ps and F/Ds are disengaged

.  
Above 400 feet RA, select a different pitch or roll mode.

.  
If the roll mode is changed first:

.  
the selected mode engages in single A/P roll operation and is controlled by the A/P which was first in CMD

.  
pitch remains in dual A/P control in TO/GA mode.

.  
If the pitch mode is changed first:

Copyright . The Boeing Company. See title page for details.
4.20.20   June 7, 2002

Automatic Flight -System Description 737 Operations Manual
.  
the selected mode engages in single A/P pitch operation and is controlled by the A/P which was first in CMD

.  
the second A/P disengages

.  
the roll mode engages in CWS R.

.  
The A/T GA mode is terminated when:

.  
another pitch mode is selected

.  
ALT ACQ annunciates engaged.

Note:  The pitch mode cannot be changed from TO/GA until sufficient nose–down trim has been input to allow single channel A/P operation. This nose–down trim is automatically added by the A/P to reset the trim input made by the A/P at 400 feet RA and (as installed) at 50 feet RA during the approach.
With pitch mode engaged in TO/GA, ALT ACQ engages when approaching the selected altitude, and ALT HOLD engages at the selected altitude if the stabilizer position is satisfactory for single A/P operation.
　
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