When operating the transponder on the VFR code 1200, what is the minimum mode the transponder must be in?

• A. Mode A
• B. Mode C
• C. Mode S
• D. Mode E

Answer: (A)

The essential idea is that for standard VFR flight using the 1200 squawk code, you only need a transponder that can identify your aircraft by a code. Transmitting Mode A provides a four-digit code to ATC, which is enough to identify you on radar as a VFR aircraft when you’re squawking 1200. Altitude information isn’t part of that code, so you don’t get altitude data with just Mode A. Altitude reporting (Mode C) is required only in airspace or situations where ATC requires altitude encoding, which isn’t a blanket requirement for all VFR flights. More advanced modes like Mode S offer extra capabilities but aren’t required for basic VFR squawking 1200. Mode E isn’t needed for this basic VFR operation either. So the minimum you need is Mode A.