An active HUD boresight alignment system for correcting a boresight of a HUD in an aircraft relative to an aircraft boresight is described. The system has an aircraft IRU, a HUD angular orientation detector and a detector. The aircraft IRU is rigidly coupled with the aircraft and configured to define an aircraft boresight indicative of a three axis angular orientation of the aircraft. The HUD angular orientation detector is rigidly arranged relative to at least one component of the HUD in the aircraft, and configured to determine a HUD boresight indicative of a three axis angular orientation of the HUD. The processor is coupled with the aircraft IRU and the HUD angular orientation detector and configured to determine a boresight angular offset of the HUD boresight to the aircraft boresight for at least one axis of the three axis angular orientation, and to correct for the boresight angular offset based on the determined boresight angular offset.