The Weird and Wonderful Logic

A318/A319/A320/A321
Professional
The Weird and Wonderful Logic
Vol
8
8-03-6
10 July 2018
PHASES
In Airbus logic every flight is divided into stages and stages are very important to understand the logic of
the Airbus systems. Consider a stage to be a combination of system settings and parameters. There are 8
phases:
• PREFLIGHT
• TAKE_OFF
• CLIMB (CLB)
• CRUISE (CRZ)
• DESCENT (DES)
• APPROACH (APPR)
• LANDING
• GO AROUND
In a flight, even a very short one, all these stages will follow each other (or course expect the Go Around).
When this chain of phase is not completed some of the automation of the aircraft systems will not be
available!
PHASE TRIGGERS
A phase trigger switches one phase into the next phase. These triggers (events) can be complex but can be
simplified like this:
• PREFLIGHT
o Thrust levers to FLX or TOGA
• TAKE_OFF
o Reaching ACCEL altitude that was set in the MCDU PERF page
• CLIMB (CLB)
o Reaching cruise altitude that was set in the MCDU PERF page
• CRUISE (CRZ)
o Manual activation of descent and leaving cruise altitude (keep in mind that in most
settings the Airbus will not start to descent without pilot interaction!)
• DESCENT (DES)
o Manually activate and confirm APPR in the MCDU PERF page
• APPROACH to LANDING
o Touchdown or Autopilot disconnected
• APPPROACH to DONE
o 30 seconds after landing and INIT or PERF pb is pressed
Alternative from APPROACH to LANDING:
• APPROACH to GO AROUND
o Thrust Levers to TOGA while in APPROACH phase