Designed for general aviation use, the Altilert is a portable device to help the pilot maintain an assigned or desired altitude.
It's use is simple. Fly to your desired altitude and turn the unit on. The Altilert learns your current altitude (by sampling barometric pressure, just like your altimeter) and stores this information. As your altitude drifts, an error signal is generated. At approximately +/- 100 ft. (or 50 ft. in Precision Mode), the red indicator flashes quickly and is accompanied by a piezo horn. The horn can be silenced by pressing the push button switch. Alarms will clear upon return to your original altitude. A new desired altitude can be set by turning the unit off and back on at any time.