When is a 'BC' clearance issued to a pilot?

A 'BC' clearance is specifically issued to a pilot for a back course approach. This type of approach is when an aircraft is navigating towards the final approach course using the back side of the localizer signal, which typically occurs in situations where the runway is not aligned with the current flight path.

In air traffic control, effective and clear communication is essential for ensuring safety and efficiency during landings and approaches. When a pilot receives a 'BC' clearance, it indicates that they should use the back course for their approach and be aware of any specific instructions or procedures that accompany this type of landing.

The other choices refer to different flight operations that do not pertain to back course approaches. For example, contact approaches are different procedures altogether that do not require a 'BC' clearance, and clearances related to the outer marker or climbing/descending are not specifically linked to back course operations. Thus, the context of the 'BC' clearance is unique and distinct, reinforcing that it is issued solely for back course approaches.