Continuous display of pitch attitude beyond normal limits of plus or minus 20 degrees is provided by an extended pitch indicator whose operation is coordinated with a primary pitch indicator which provides pitch information through primary ascent and descent ranges (plus or minus 20 degrees). Operation of the extended pitch indicator is coordinated with operation of the primary pitch indicator in such a manner that the extended pitch indicator is hidden from view during flight maneuvers within the primary climb and dive ranges, but which is automatically exposed during flight maneuvers outside of the primary climb and dive ranges. In the preferred embodiment, the extended pitch indicator element is attached to the pitch gimbal and a horizon mask 15 interposed between the extended pitch indicator and the primary pitch indicator scale. A window opening formed in the horizon mask is uncovered as the primary pitch indicator element is displayed, thereby exposing the extended pitch indicator and its markings which indicate the extended pitch information lying within the extreme pitch limits.
The invention describes a method for electronically adjusting the viewing angle of a liquid crystal display within a panel fixed in location by the structure within which it is located, such as an electronic flight indicator unit. The adjustment in viewing angle is achieved by changing the bias voltage to alter the pre-tilt angle of the liquid crystal layer.
