Which equipment suffix indicates a transponder with Mode C capability?

The correct suffix that indicates a transponder with Mode C capability is /U. Mode C is essential for aircraft to provide altitude information in addition to identification codes, allowing air traffic control to have a three-dimensional picture of traffic. This capability enhances situational awareness and maintains safe separation between aircraft.

In the context of transponder equipment suffixes, each designation serves a specific function. The /U suffix designates a transponder that is equipped to utilize both Mode A (which provides a basic squawk code) and Mode C (which adds altitude reporting). This combination is critical for operations in controlled airspace where altitude awareness is vital.

Other suffixes do indicate different capabilities, but they do not represent transponder Mode C specifically, highlighting the distinct role of the /U suffix in air traffic management.