Which of the following is NOT a method authorized for navigation on LOC-based courses?

Monitoring raw LOC data is an important method utilized for precise navigation on Localizer (LOC) courses. This method helps pilots maintain the correct course and assists in ensuring alignment with the runway.

On the other hand, using a substitute for the final approach segment, navigating on the back-course guidance, and utilizing procedures identified as "NA" (not authorized) without exception by NOTAM are all methods that should not be used. A final approach segment substitute might not provide the necessary information for safe landings, while back-course navigation generally does not provide reliable track guidance for a typical approach, and procedures marked as "NA" are explicitly prohibited for use, indicating they do not meet safety or operational criteria.

Thus, the method authorized for LOC-based navigation that does not align with acceptable practices is monitoring raw LOC data, confirming that it is indeed a legitimate technique for accurate guidance rather than an incorrect one.