Systems Guide

A318/A319/A320/A321
Professional
SYSTEMS
Systems guide
Vol
4
04-03-14
11 July 2018
AUTOTHRUST MODES
FIXED THRUST MODES
• TOGO: Provides fixed maximum
thrust and is only available when
autothrust status is armed.
• FLX: Flex thrust is used for reduced
thrust takeoffs. Thrust is
calculated using the assumed
temperature as set in the MCDU.
• MCT: Provides Maximum
Continuous Thrust at the current
ambient conditions.
• CLB: Provides fixed thrust equal to
the climb thrust rating at current
ambient conditions.
• IDLE: Provides fixed idle thrust.
Only available in active autothrust status. Note the thrust levers can be anywhere in the
autothrust range!
• THR: When the thrust is not TOGA, FLX, MCT or CLB the fixed thrust is called THR.
VARIABLE THRUST MODES
• SPEED: The autothrust system will provide variable thrust to maintain a set speed or a managed
speed in level flight or when the aircraft follows a programmed flight path. Only available when
autothrust is active.
• MACH: Identical to speed mode but not available at low altitudes. The speed mode is
automatically switched to Mach mode (and vice versa) at a preset altitude.
AUTOTHRUST/FLIGHT DIRECTOR/AUTOPILOT
The vertical guidance modes use pitch to maintain a target speed or a specific vertical path. If vertical
guidance modes are used to control a target speed, autothrust uses a fixed thrust mode. If vertical
guidance modes are used to control a specific vertical path, autothrust uses variable thrust to maintain
target speed. When manually flown in fixed autothrust mode the flight director’s pitch command bar
indicates the pitch needed to fly the desired speed.