Automatic CPCS

-   The automaticity of a cabin pressure control system is entirely relative. All systems contain many automatic functions.
-   That is, provision is made for manual override only for an emergency condition. In general, as the degree of desired cabin pressure comfort increases, the system complexity increases, and typical commercial airliner systems incorporate a considerable number of automatic features eliminating the necessity for crew attention. 
-   Automatic electronic systems are often defined as systems containing logic elements which automatically adapt the mode of cabin pressure control to changes in flight plan after takeoff. The most modern of automatic systems permit the crew to select the landing field elevation prior to takeoff and to use any desired flight profile without inflight adjustment of the system.