What information does a transponder provide to air traffic control, and what is Mode S?

What information does a transponder provide to air traffic control, and what is Mode S?

• A. It transmits weather updates to ATC.
• B. It replies to radar interrogations with identification and altitude; Mode S adds selective addressing and data reporting for surveillance.
• C. It stores flight plans on demand.
• D. It provides engine health status to maintenance.

Answer: (B)

A transponder is part of the secondary surveillance radar system used by air traffic control. When ATC interrogates it, the transponder replies with coded information that helps identify the aircraft and report its altitude. This is how controllers know who is in the air and roughly how high they are. Weather updates, stored flight plans, or engine health data aren’t provided by the transponder itself. Mode S is an enhanced version of the transponder. It gives each aircraft a unique address, so ATC can selectively query a single airplane rather than everyone in the vicinity. This selective addressing reduces radar clutter and improves surveillance reliability. In addition to identification and altitude, Mode S supports data reporting for surveillance, meaning more information can be sent to ATC (and other systems) about the aircraft as needed.

A transponder is part of the secondary surveillance radar system used by air traffic control. When ATC interrogates it, the transponder replies with coded information that helps identify the aircraft and report its altitude. This is how controllers know who is in the air and roughly how high they are. Weather updates, stored flight plans, or engine health data aren’t provided by the transponder itself.

Mode S is an enhanced version of the transponder. It gives each aircraft a unique address, so ATC can selectively query a single airplane rather than everyone in the vicinity. This selective addressing reduces radar clutter and improves surveillance reliability. In addition to identification and altitude, Mode S supports data reporting for surveillance, meaning more information can be sent to ATC (and other systems) about the aircraft as needed.