Systems Guide

Aerosoft
Airbus A320/A321
SYSTEMS
Systems guide
Vol
4
04-03-18
28 October 2014
ARMING CONDITIONS
 FCU selected altitude is below current altitude
 TAKE OFF, GO AROUND or LAND mode is not engaged
DISARMING CONDITIONS
 Selecting any other vertical mode
 FCU selected altitude is above current altitude
 Loss of NAV, LOC or vertical path validity
 Selecting GO AROUND mode
ENGAGEMENT CONDITIONS
 FCU selected level is below current altitude
 NAV, LOC* or LOC is active
 TAKE OFF, GO AROUND, LAND, FINAL not active
 DES mode is engaged automatically when an altitude constraint is met with DES mode armed.
 DES mode is manually engaged by pushing the ALT selector knob
DISENGAGEMENT CONDITIONS
 Engagement of any other vertical mode
 Selecting a FCU altitude above current altitude
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 taken into account 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.