What information does a fully operational radar system provide regarding altitude?

A fully operational radar system provides current altitude and deviations. This is crucial for air traffic controllers as it allows them to monitor not only the altitude at which an aircraft is flying at any given moment but also any deviations from the planned flight levels. This information enables controllers to maintain safe vertical separation between aircraft, especially in congested airspace and during altitude changes.

Monitoring current altitude is essential for ensuring that aircraft comply with altitude assignments, and the ability to see deviations helps controllers intervene when necessary, enhancing safety and efficiency in air traffic operations. The radar system also tracks these changes in real time, providing a dynamic view of air traffic, which is vital for effective air traffic management.

The other answer choices miss critical aspects of altitude tracking. For instance, only the highest altitude reached does not provide valuable ongoing data about the aircraft's current status or any necessary adjustments. Planned altitude exclusively would not reflect real-time changes or compliance, which are crucial for safety. Lastly, altitude in relation to the ground alone does not account for established air traffic control altitudes and could lead to dangerous situations if not contextualized within controlled airspace.