Cabin Pressure Controller
Cabin altitude is normally rate–controlled by the cabin pressure controller up to a cabin
altitude of 8,000 feet at the airplane maximum certified ceiling of 41,000 feet. The cabin
pressure controller controls cabin pressure in the following modes:
- AUTO – Automatic pressurization control; the normal mode of operation uses a DC
motor. - ALTN – Automatic pressurization control; the alternate mode of operation uses a DC
motor. - MAN – Manual control of the system using DC motor.
The air data inertial reference units (ADIRUs) provides ambient static pressure, baro
corrected altitude, non corrected altitude and calibrated airspeed to both automatic
controllers. The ADIRUs receive barometric corrections from the Captain’s and First
Officer’s BARO reference selectors. The automatic controllers also receive throttle position
from both stall management computers and signals from the air/ground sensors.
