This specification covers integrally-lighted altimeters that have an electromechanically servo driven pointer and a digital display of corrected altitude. The altimeters operate in the normal mode to display altitude transmitted by altitude computers or central air data computers. The altimeters incorporate an integral pressure sensor with electronic outputs to aid operation in the normal mode and to provide altitude inputs for the electronic display of pressure altitude when operated in the standby mode. The altimeters also incorporate an electrical output of barometric pressure setting which is required by some aircraft. A method is provided on the bezel of the altimeter for the selection of barometric setting to be displayed in either inches of mercury (in. hg) or millibars (mb). The altimeters are designed to operate from the following power sources: 115V, 400Hz (primary), 28V DC (secondary), and 18V DC (battery mode) from an optional rear mounted battery module. Altimeters meeting the requirements of this specification are interchangeable with AAU-19/A, AAU-19A/A, and AAU-19B/A, AAU-34/A, and AAU-37/A Altimeters.
