Abstract: A substantially self-contained digital instrumentation module (30) for fixed and rotary wing aircraft provides flight and other situational information, such as attitude, altitude, airspeed, and slip information, during normal aircraft operation or during emergencies, such as a failure of the aircraft's primary instrumentation. The module (30) can be mounted in any of various possible orientations. It includes redundant memories (38,40,50,52) to preserve back-up copies of software and settings during upgrades and changes. It partitions certified software from non-certified software. It can receive software upgrades and settings changes via a common portable memory device. It can automatically calculate and synchronize barometric pressure with the aircraft's primary instrumentation. It also allows for creating a customizable dimming curve (220,222), and for creating customizable range markings (114).