Which type of approach is prohibited?

• A. ILS
• B. Localizer Type Directional Aid
• C. Backcourse
• D. RNAV (GNSS) Approach

Answer: (C)

Backcourse approaches use the localizer signal from the opposite direction, so the indicator that shows how you’re off course behaves in the opposite sense. The CDI deviation and the TO/FROM information can be misleading when flying toward the runway on the back course, making it easy to misinterpret your position and drift off the centerline. Because of this potential for confusion and the limited reliability of vertical guidance on that path, many procedures designate backcourse approaches as prohibited at certain airports. In contrast, ILS, LDA, and RNAV (GNSS) approaches are standard, published guidance with clearer, unambiguous guidance and are generally authorized.