A localizer offset greater than 3 degrees from the runway center-line is designated with an identifier starting with which letter?

A localizer offset greater than 3 degrees from the runway center-line is designated with an identifier starting with which letter?

• A. X
• B. I
• C. C
• D. Y

Answer: (A)

When a localizer’s course is offset more than 3 degrees from the runway centerline, it’s treated as an offset localizer rather than a standard ILS. To distinguish this on charts and in nav data, the facility’s identifier starts with the letter X. That X-prefix signals to pilots that the approach is not aligned with the runway and may behave differently from a conventional ILS, often requiring attention to the actual inbound course and any differences in minima or guidance. In practice, you’ll use the X-designated localizer as the reference for the approach, recognizing it’s an offset facility rather than a true runway-centered ILS localizer.

When a localizer’s course is offset more than 3 degrees from the runway centerline, it’s treated as an offset localizer rather than a standard ILS. To distinguish this on charts and in nav data, the facility’s identifier starts with the letter X. That X-prefix signals to pilots that the approach is not aligned with the runway and may behave differently from a conventional ILS, often requiring attention to the actual inbound course and any differences in minima or guidance. In practice, you’ll use the X-designated localizer as the reference for the approach, recognizing it’s an offset facility rather than a true runway-centered ILS localizer.