Final answer:
The localizer first letter identifier 'X' means that the alignment of the localizer is more than 3 degrees off the runway heading.
Step-by-step explanation:
The student has asked a question related to aviation navigation systems, specifically the localizer component of an Instrument Landing System (ILS). The localizer provides lateral guidance to aircraft approaching a runway. The specific question pertains to the meaning of the first letter identifier 'X' in a localizer frequency. In the context of ILS localizer identifiers, if the first letter is an 'X', it indicates that the alignment of the localizer (LOC) is more than 3 degrees off the runway heading (RWY HDG).