The Altimeter is a panel-mounted indicator that provides the pilot with a display of baro-corrected altitude and provides encoded altitude signals to a transponder. The pneumatic Encoding Altimeter displays baro-corrected altitude on the familiar counter-drum-pointer presentation. The pointer makes one revolution per thousand feet. The dial graduations are at twenty-foot increments, and the counter indicates altitude in ten thousand, thousands and hundreds of feet. A knob-settable counter displays the barometric pressure in inches of mercury and millibars. Setting of the barometric scale knob offsets the output and the display, but does not affect the reported altitude sent to the transponder by the encoder in the unit. Reported altitude is always relative to standard pressure (29.92 inches Hg). Indicator markings are white on a black background. The principle components of the altimeter are: two capsules, a mechanism assembly, a dial, a pointer, a counter for altitude presentation, a counter for setting local barometric conditions, a vibrator assembly, and an optical encoder assembly. An ALERT light, mounted on the bezel, is electrically connected to the output of a companion altitude alerter. The Altimeter is 6.86 inches long, 3.26 inches wide, 3.26 inches high and weighs 2.85 pounds.