An aircraft pneumatic cabin pressure control system that is adapted to
prevent the difference between cabin pressure and atmospheric pressure
from exceeding a threshold value wherein the threshold value varies in
relation to aircraft altitude. In some instances the control system
includes at least one outflow valve adapted to prevent the difference
between cabin pressure and atmospheric pressure from exceeding a
threshold value, and the control system is adapted to override the
outflow valve at predetermined altitudes. The control system may
implement a method for controlling the cabin pressure of an aircraft
using a pneumatic cabin pressure control system that includes an outflow
valve comprising at least two pressure input ports, the method comprising
coupling an isolation valve to an input port of the outflow control valve
and utilizing the interrupt valve to isolate the outflow valve input port
to which the isolation valve is coupled from pressure changes.