Method and apparatus for generating heading error data used by an Electronic Flight Director

An improved Horizontal Situation Indicator module for use with an aircraft, wherein the HSI module is adapted for accepting Bank Angle Commands or waypoint data from a GPS flight module and for using the same to determine a heading error. The HSI module is further adapted for outputting the heading error to the Flight Director module where it can be used to create a Roll Command for output to the Auto-Pilot, whereby the Auto-Pilot can be commanded to follow a turn using the HSI and the Flight Director without requiring an additional module be added to the aircraft to create the heading error for use by the Flight Director.