Which service provides information to the flight deck via data link using the S-mode transponder and altitude encoder to improve see-and-avoid?

• A. A radar display for ATC
• B. A ground-based service that provides information to the flight deck via data link using the S-mode transponder and altitude encoder to inform of nearby traffic
• C. An onboard collision avoidance system
• D. An air traffic advisory service

Answer: (B)

Data link traffic information services bring ground-based radar and ADS-B data into the cockpit to help you see other aircraft. The system uses information from the Mode S transponder and altitude encoding to determine and broadcast nearby traffic to the flight deck, so you can see and assess potential conflicts even when you’re scanning visually. This ground-based service enhances your see-and-avoid by providing real-time traffic relative to your position and altitude.

Radar displays for ATC are controlled by air traffic control, not a flight-deck data-link service you receive directly for see-and-avoid. An onboard collision avoidance system (TCAS) operates using its own transponder interrogations and own-ship data, independent of ground-based broadcast traffic. An air traffic advisory service is ATC guidance and coordination, not the cockpit data-link traffic information broadcast to you.