Under what conditions can an IFR aircraft be vectored by a radar controller?

The correct answer is based on the regulatory framework guiding air traffic control procedures for IFR aircraft. An IFR (Instrument Flight Rules) aircraft can be vectored by a radar controller specifically within controlled airspace and at or above the designated minimum altitude.

Controlled airspace is where air traffic control services are provided, and proper vectoring is essential for maintaining safe aircraft separation and efficient traffic flow. The appropriate minimum altitude refers to heights established to ensure safe vertical separation from obstacles, terrain, and other air traffic. By requiring that aircraft be at or above this altitude when vectored, it helps to maintain safety standards.

The other options do not align with established procedures for IFR operations. For instance, vectoring in uncontrolled airspace is generally not permitted, as there is no air traffic control service to provide the necessary safety oversight. Similarly, allowing vectoring below the minimum en route altitude (MEA) could compromise safety because it may not provide the necessary obstacle clearance. Lastly, visual flight rules (VFR) involve different operational parameters and are not applicable to controlled radar vectoring procedures for IFR flights.