Category III (CAT III) ILS is best described as:

Category III (CAT III) ILS is best described as:

• A. ILS that allows landing in the lowest of visibilities and is the most complex and expensive to implement and maintain.
• B. ILS with the same performance as CAT II.
• C. Non-precision approach.
• D. ILS that requires inner markers.

Answer: (A)

CAT III ILS is described as an approach that allows landing in the lowest visibility and is the most complex and expensive to implement and maintain. This category supports very low decision heights or even decision altitudes and extremely short runway visual range, thanks to advanced ground equipment, tighter performance tolerances, and, in many cases, automated landing capability. The system relies on precise localizer and glide slope signals, a comprehensive approach lighting system, and rigorous maintenance, calibration, and certification to ensure reliability in poor visibility. Because of the need for such high-precision equipment, extensive redundancies, and specialized training and procedures for crews and operators, the overall cost and complexity are greater than for CAT II or other categories. The other statements don’t fit because CAT II does not reach the same extremely low minima, ILS is a precision approach with vertical guidance (not a non-precision approach), and inner markers are not a defining requirement of CAT III—many CAT III approaches are markerless or use other navigation aids.

CAT III ILS is described as an approach that allows landing in the lowest visibility and is the most complex and expensive to implement and maintain. This category supports very low decision heights or even decision altitudes and extremely short runway visual range, thanks to advanced ground equipment, tighter performance tolerances, and, in many cases, automated landing capability. The system relies on precise localizer and glide slope signals, a comprehensive approach lighting system, and rigorous maintenance, calibration, and certification to ensure reliability in poor visibility. Because of the need for such high-precision equipment, extensive redundancies, and specialized training and procedures for crews and operators, the overall cost and complexity are greater than for CAT II or other categories.

The other statements don’t fit because CAT II does not reach the same extremely low minima, ILS is a precision approach with vertical guidance (not a non-precision approach), and inner markers are not a defining requirement of CAT III—many CAT III approaches are markerless or use other navigation aids.