Are additional services provided on a mandatory basis?

The reason the response indicating that additional services are required only as workload permits is accurate relates to how air traffic control services are structured and their operational flexibility. In the context of air traffic management, additional services such as flight advisories, traffic advisories, or any supplemental information are provided based on the available resources of the controller and the current air traffic workload.

In busy airspace or during peak operational periods, controllers may prioritize essential services to ensure safety and efficiency, which means they may not be able to provide all additional services at all times. Conversely, during less busy periods, controllers have the ability to offer more comprehensive services without compromising safety. This flexibility ensures that controllers focus their efforts where they are most needed while also accommodating additional services when feasible.

The other options suggest that additional services are either fully optional or mandatory in all cases, which does not accurately represent the nuanced nature of air traffic control responsibilities. While certain services may be required under specific circumstances, the requirement ultimately hinges on the workload and resource availability, leading to the correct understanding that additional services are provided as workload allows.