Gives Nearly Immediate Vertical Speed Information The FAA has granted SANDIA Aerospace an additional TSO on their popular SAI 340 Quattro multi-function indicator. In addition to Attitude, Altitude, Airspeed and slip, the SAI 340 is now TSO’d for (I)VSI. (I)VSI is Instantaneous Vertical Speed.
Source: aero newsFAA Grants TSO To Sandia For (I)VSI