Which statement is true about Category III (CAT III) ILS compared to CAT II?

Which statement is true about Category III (CAT III) ILS compared to CAT II?

• A. CAT III is less complex and cheaper to implement than CAT II.
• B. CAT III uses no inner marker.
• C. CAT III has stricter RVR criteria than CAT II.
• D. CAT III is the most complex and expensive to implement and maintain.

Answer: (D)

CAT III ILS is designed to operate in much lower visibility, which requires a far higher level of automation, redundancy, and system integrity than CAT II. To reliably land under those tougher conditions, the ground equipment, navigation guidance, and flight control systems must be more sophisticated and tightly monitored, with multiple fail-safes, continuous performance checks, and stringent maintenance and certification processes. That combination drives significantly higher installation costs, ongoing maintenance, and training requirements. So the overall picture is that CAT III is the most complex and expensive to implement and maintain. While stricter RVR (visibility) minima are indeed associated with CAT III compared to CAT II, the central point is the increased technology, redundancy, and reliability demands, which explains the greater cost and complexity. Marker usage or other specific features can vary by installation, but they don’t define the difference as clearly as the need for advanced automation and reliability.

CAT III ILS is designed to operate in much lower visibility, which requires a far higher level of automation, redundancy, and system integrity than CAT II. To reliably land under those tougher conditions, the ground equipment, navigation guidance, and flight control systems must be more sophisticated and tightly monitored, with multiple fail-safes, continuous performance checks, and stringent maintenance and certification processes. That combination drives significantly higher installation costs, ongoing maintenance, and training requirements. So the overall picture is that CAT III is the most complex and expensive to implement and maintain.

While stricter RVR (visibility) minima are indeed associated with CAT III compared to CAT II, the central point is the increased technology, redundancy, and reliability demands, which explains the greater cost and complexity. Marker usage or other specific features can vary by installation, but they don’t define the difference as clearly as the need for advanced automation and reliability.