Instantaneous Vertical Speed Indicator

Instantaneous Vertical Speed Indicator

Some manufacturers came up with a solution to accelerate the indication and they called it IVSI or Instantaneous Vertical Speed Indicator.
Some aircraft are equipped with an instantaneous vertical speed indicator (IVSI), which incorporates accelerometers to compensate for the lag.
These pistons give an instantaneous pressure increase (descent) or decrease (climb) in the static supply before the choke as soon as a vertical.
Instantaneous Vertical Speed Indicator