Abstract: An aircraft heading reference system including a rate gyro for sensing the yaw rate .psi. of the aircraft and producing electrical signals representative thereof; a rate gyro for sensing the pitch rate .theta. of the aircraft and producing electrical signals representative thereof; an air speed sensor for sensing air speed .nu. of the aircraft and producing electrical signals representative thereof; a roll angle computer circuit responsive to the electrical signals representative of the yaw rate, pitch rate, and air speed for determining an electrical signal representative of the roll angle .phi. according to the expression:.psi.+.theta. tan .phi.=(tan .phi./cos .phi..multidot.(g/.nu.)and a yaw and pitch computer circuit, responsive to the pitch rate .theta., yaw rate .psi., and roll angle .phi. electrical signals for resolving the yaw and pitch rates about the roll angle .phi. to provide an electrical signal representative of the heading rate of the aircraft.