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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Automatic Flight -System Description 737 Operations Manual
Automatic Flight Approach Profile
G/S Capture
. GA displayedon Thrust Mode Display
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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:
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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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