Systems Guide

A318/A319/A320/A321
Professional
SYSTEMS
Systems guide
Vol
4
04-03-20
11 July 2018
GUIDANCE
In DES mode the aircraft is guided along the DES PATH. The SPD target can be selected or managed (with
the speed to vary around the calculated optimal nominal descent speed. SPD CSTR is considered in the
speed profile.
If the aircraft is above the DES PATH it will pitch down until the upper limit of the MANAGED SPD RANGE
is reached. That speed will be kept, and the aircraft will differentiate from the DES PATH. Extending ½
speed brakes will allow the aircraft to get back on the calculated path.
If the aircraft is below the DES PATH the aircraft will maintain the target speed until the DES PATH is
reached.
OPEN DESCENT
In selected descend mode the autothrust system will be set to idle and the set speed will be kept using
pitch. This mode is not useful for final approaches.
ENGAGEMENT CONDITIONS
• The aircraft must be in flight more than 5 seconds
• LAND mode is not engaged
• FCU selected altitude is lower than current altitude
• OPEN DESCENT is engaged by pulling the ALT selector knob
DISENGAGEMENT CONDITIONS
• Selecting any other vertical mode
• Selecting a higher altitude then the current altitude
GUIDANCE
In OPEN DES the target Speed / Mach is maintained by pitch controls and thrust is maintained by the A /
THR or manually by the pilot. Speed target can be selected or managed.
ALTITUDE ACQUIRE
ALT* will guide the aircraft to the FCU selected altitude, ALT CST* guides the aircraft to an altitude
constraint. Once the set altitude is reached the ALTITUDE HOLD (ALT or ALT CST) mode will engage.