Which of the following is a function of radar guidance in air traffic control?

Radar guidance in air traffic control primarily serves to provide navigational assistance. One of its key functions is to offer pilots specific headings to follow, helping to ensure safe and efficient flight paths. This capability is crucial in busy airspaces where aircraft must be properly spaced and routed to prevent collisions and ensure orderly traffic flow.

Additionally, radar systems track the position and movement of aircraft in real-time, allowing controllers to communicate necessary adjustments in headings, altitude, and speed as needed. This active guidance helps manage air traffic and enhance safety by keeping aircraft separated.

The other options provided do not capture the core functions of radar guidance in air traffic control. For instance, while route establishment is part of air traffic management, it is a broader concept not limited to radar functions alone. Visual tracking of aircraft is typically performed by air traffic controllers using radar displays rather than direct visual observation. Monitoring pilot health and performance is not a function of radar systems; rather, it falls under different procedures related to flight safety and operational assessments.