The Mach Airspeed Indicator (MASI) is an RVSM compliant unit. In Standby mode, it processes pitot-static pressure, total air temperature, and altitude input data to compute and display calibrated airspeed (CAS), true airspeed (TAS), Mach number, and not-to-exceed airspeed (Vmo) data. In Normal mode, it displays CAS, TAS, ground speed (GS) Mach number, Vmo, and angle of attack (AoA) data provided by the IS&S 9B-81010-22 Digital Air Data Computer (DADC) via ARINC 429.
The MASI provides a dedicated digital display of Mach number and analog display of CAS, using a liquid crystal display (LCD) and E/M controlled pointer. The LCD also displays CAS, GS, or TAS, as selected by the operator. Vmo and AoA are displayed using a segmented arc. The LCD has high intensity backlighting for daytime use and low level white lighting for nighttime viewing. When connected to an IS&S Altimeter (9D-80110- 22), SSEC corrected air data is provided on the Altimeter and the MASI. Up to 16 different SSEC curves are selected through rear connector pin programming. It performs airspeed hold monitor and overspeed alert functions, as well as data checking, fault detection and status indication functions. A multifunction PUSH SEL pushbutton selects operating mode and airspeed displays. The MASI also has a Command Bug Adjust Knob for setting target airspeeds, IMI Ring Markers used in setting airspeed reference points, and a TEST Button for activating the instrument self-test and fault history display functions.