Which navigation aid is used for nonprecision approaches with a final course that may be offset and wider than the localizer?

• A. Simplex
• B. Slaved compass
• C. Simplified directional facility
• D. Slant range

Answer: (C)

The key idea is recognizing the Simplified Directional Facility as a nonprecision approach aid that can have an offset and wider final approach course than a localizer. The SDF provides lateral guidance like a localizer, but its final approach path may be offset from the runway centerline and is wider, and it does not provide vertical guidance. That means you fly to a minimum descent altitude (MDA) and rely on step-down fixes or published altitudes rather than a glide path. The other items are not instrument approaches: Simplex isn’t a navigation aid for approaches, a slaved compass is a heading reference instrument, and slant range is a distance measurement, not an approach aid.