Air Traffic Control Systems and Procedures Practice Test 2026 – Your All-in-One Guide to Mastering ATC Success!

The main idea is that primary radar and SSR obtain information in two different ways. Primary radar sends out a pulse and measures the echoes off any object. It can show you where something is in range and bearing, and it can detect non-cooperative targets, but it provides no identity or altitude data because there’s no data coming from the target itself.

SSR, on the other hand, is a two-way system. The ground radar interrogates, and the aircraft’s transponder replies with coded information. That reply carries the aircraft’s identity (flight ID) and altitude (Mode C, and more with Mode S). Because it relies on the aircraft’s transponder, SSR data is only available if the aircraft is cooperative and transponding.

So the correct statement captures that primary radar detects objects by echoes without identity/altitude data, while SSR uses transponder replies to identify and supply altitude and flight data, and it requires a cooperative transponder. The other choices misstate how SSR or primary radar obtain information or whether SSR can operate without a transponder.