Systems Guide

A318/A319/A320/A321

Professional

SYSTEMS

Systems guide

Vol

04-03-19

11 July 2018

DESCENT

DES mode provides vertical guidance following a computed descent profile between Top of Descent to the

Deceleration point. It uses the data in the F-PLN and the available WIND data. It is divided into three

sections:

• Re-pressurization segment (ignored in our simulation)

• Idle Path segment where the engines are at idle and AP / FD controls SPD

• Geometric path when the AP / FD controls vertical path and the A /THR controls the SPD

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