Plain English Meaning

Small sensors that feel changes in motion. In some vertical speed indicators they pick up the moment the airplane starts to climb or descend, so the needle moves right away instead of lagging.

Full Definition

Sensing devices that detect and measure changes in velocity (acceleration) along one or more axes. In a Vertical Speed Indicator that uses Instantaneous Vertical Speed Indicator (IVSI) technology, accelerometers sense the initial vertical acceleration of the aircraft when a climb or descent begins, allowing the instrument to display vertical speed almost rather than waiting for the slower -based .