What type of services are provided when the work situation permits?

The correct answer is Additional Services because this terminology typically refers to services that are not strictly necessary but are provided when circumstances allow. In aviation and air traffic control, these services enhance safety, efficiency, and the overall quality of the flight experience but do not pertain to essential operations.

Essential services are the core functions required for safe and efficient air traffic management, while standard services are the baseline operations provided under normal circumstances. Supplementary services could refer to those that support or complement the standard offerings but may not specifically articulate the idea of availability when the work situation allows. Thus, Additional Services captures the essence of offering extra support as conditions permit, representing the flexibility in operations that enables air traffic controllers to enhance service provision when possible.