Current heading systems are calibrated using MIL-STD 765A as a foundation document. MIL-STD 765A was originally written in the 1960s and has been revised from time to time to reflect changes in accepted procedures but still relies upon 1960s technology. This includes the use of compass roses, master site compasses, transit based systems referencing distant objects and electronic methods compliant with MIL-C-26524 (the latter requires the removal of the magnetic transmitter from the aircraft).
All of the methods described in this standard, except for the site compass, require the use of terrestrial based reference points, which may be difficult to locate under adverse weather conditions or at night. The master site compass is inherently inaccurate due to the resolution of the display and sensing device (suspended bar magnet).
The CA-320A & CA-321A Sensor is easily aligned with the longitudinal axis of the aircraft and the digital heading is presented to the technician where the adjustments take place. No interpretation or special skills are needed for precise measurement.
The CA-320 and CA-321 have the following certifications: