The Collins PRE-80C panel mounted Preselector/Alerter provides a readout of the selected flight altitude. The PRE-80C also provides advance notice when approaching the set altitude and when deviating more than 300 feet from that altitude (or more than 200 feet with SB 5 installed). The PRE-80C is part of the digital ADS-80 Air Data System and is not compatible with synchro type altimeter/preselect systems. The PRE-80C's selected altitude ranges from 0 to 49,000 feet. The altitude display is controlled by a 2-speed set knob on the PRE-80C with a switch that then actuated by pressing the alert lamp, controls the cancel and self-test functions.
The PRE-80C is housed in an aluminum case measuring 3.39 inches wide, 7.765 inches long, 1.672 inches high weighing 1.32 pounds maximum. The PRE-80C has variations with 5V or 28V panel-lighting, blue-white or clear-white lighting color, 5V or 28V warning lighting, black or gray bezel color and ±300 feet or ±200 feet deviations dependent on the part number.