What is an altitude readout in radar displays?

An altitude readout in radar displays refers to the altitude transmitted by an aircraft's Mode C transponder, which provides information about the aircraft's altitude in 100-foot increments. This data is crucial for air traffic controllers as it aids in maintaining proper vertical separation between aircraft, ensuring safe and efficient operations within controlled airspace.

Mode C transponders are equipped in most commercial aircraft and automatically transmit the aircraft's altitude along with its identity and position information. This enables radar systems to accurately display an aircraft's altitude in real-time, allowing controllers to monitor and manage multiple aircraft effectively.

In contrast, other options do not accurately describe an altitude readout: speed is unrelated to altitude readouts, while 50-foot increments are not typically used in this context. A visual representation of flight paths pertains more to flight trajectory than current altitude data. Thus, knowing that an altitude readout comes from a Mode C transponder and is displayed in 100-foot increments is essential for understanding how altitude information is processed in air traffic control systems.