Unless instructed otherwise by ATC, what transponder code should pilots operating VFR select when flying at or below 12,500 feet ASL?

When flying under Visual Flight Rules (VFR) at or below 12,500 feet Above Sea Level (ASL), pilots are required to set their transponder to code 1200, which is the standard VFR code. This code allows air traffic control (ATC) to identify VFR flights in the radar environment and is crucial for maintaining situational awareness and safety in the airspace.

The code 1200 indicates that the aircraft is not operating under instrument flight rules (IFR) and helps to differentiate VFR traffic from IFR traffic. Therefore, selecting this transponder code when flying VFR ensures compliance with regulations and enables ATC to effectively manage the airspace.

Other transponder codes, such as 1400, 1300, and 1500, are not the standard VFR codes and may lead to confusion or misidentification in the radar system. Hence, pilots must use 1200 when operating VFR below 12,500 feet unless ATC provides different instructions specific to the flight operation.