The System Twenty is a single-axis roll stabilization autopilot that requires zero additional panel space. The programmer, computer, annunciators, and servo amplifier are entirely contained within the turn coordinator case. Standard functions include heading pre-select, turn command (which will give up to 90% standard rate turn), LO & HI track modes for LOC & NAV, and a gain enhancement feature for tracking GPS navigation analog left / right deviation signals.
To utilize GPS roll steering (GPSS) commands from a compatible GPS, an additional ST-901 GPSS converter may be required. The ST-901 GPSS converter is not required when integrating to an Aspen EFD system or Garmin G500/600 EFIS.
A compatible DG or HSI is required for the heading pre-select function or when adding the optional ST-901 GPSS converter.
Building block concept allows upgrading to a System Thirty or FiftyFiveX two-axis system.