According to FARs, no foreign air carrier may operate in the United States, a turbine powered airplane that has a maximum pax seating config, excluding any pilot seat, of more than 30 seats, unless it is equipped with

• A. TCAS II
• B. TCAS II and Mode S transponder
• C. TCAS I
• D. there are no specific requirements

Answer: (B)

The main concept is that foreign air carriers operating into the United States with turbine-powered airplanes that have more than 30 passenger seats must have enhanced collision avoidance and surveillance equipment. Specifically, they must be equipped with TCAS II and a Mode S transponder. TCAS II provides the required resolution advisories to help pilots avoid mid-air conflicts, not just generic traffic advisories. TCAS I only offers advisories and does not provide the full safety capability that TCAS II delivers. The Mode S transponder adds richer surveillance data (identity, altitude, etc.) that TCAS II uses to produce accurate, reliable traffic information and to coordinate with air traffic control. Together, TCAS II and Mode S ensure the necessary level of safety and interoperability for larger aircraft operating in US airspace. The other options don’t meet the combined requirement, or imply no specific requirement.