737 Flight Crew Operations Manual
Automatic Flight -
System Description
Boeing Proprietary. Copyright © Boeing. May be subject to export restrictions under EAR. See title page for details.
D6-27370-866-EGP 4.20.5
Autothrottle Modes
• N1 – the autothrottle maintains thrust at the selected N1 limit displayed
on the thrust mode display, including full go-around N1 limit
• GA – the autothrottle maintains thrust at reduced go–around setting
• RETARD – displayed while autothrottle moves thrust levers to the aft
stop. RETARD mode is followed by ARM mode
• FMC SPD – the autothrottle maintains speed commanded by the FMC.
The autothrottle is limited to the N1 value shown on the thrust mode
display
• MCP SPD – the autothrottle maintains speed set in the MCP
IAS/MACH display. The autothrottle is limited to the N1 value shown
on the thrust mode display
• THR HLD – the thrust lever autothrottle servos are inhibited; the pilot
can set the thrust levers manually
• ARM – no autothrottle mode engaged. The thrust lever autothrottle
servos are inhibited; the pilot can set thrust levers manually. Minimum
speed protection is provided
Pitch Modes
• TO/GA – Takeoff
Engaged for takeoff by turning both F/D switches ON and pushing either
TO/GA switch. Both F/Ds must be ON to engage TO/GA prior to starting
takeoff.
The AFDS commands pitch attitude in the following order:
• 10 degrees nose down until 60 knots IAS
• 15 degrees nose up after 60 knots IAS
• 15 degrees nose up after lift–off until a sufficient climb rate is
acquired. Then, pitch is commanded to maintain MCP speed plus 20
knots.
TO/GA can also be engaged for takeoff with F/D switches OFF if a TO/GA
switch is pushed after 80 knots IAS below 2000 feet AGL and prior to 150
seconds after lift–off.
• TO/GA – Go–around
Engaged for go–around by pushing the TO/GA switch under the following
conditions:
• inflight below 2000 feet radio altitude
• inflight above 2000 feet radio altitude with flaps not up or G/S
captured
• not in takeoff mode
• either F/D ON or OFF.
September 15, 2016
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