Which type of navigational aid correlates with the need for an aircraft to be DME equipped?

DME, or Distance Measuring Equipment, is specifically designed to provide the pilot with information about the distance to a VOR station. Therefore, a VHF Omnidirectional Range (VOR) is directly related to the requirement for an aircraft to be equipped with DME. When pilots receive signals from a VOR, having DME enables them to obtain their distance from the VOR station, which is crucial for navigation and ensuring proper spacing during flight operations.

DME works in conjunction with VOR stations, enhancing navigational accuracy, especially in complex airspace or during approach and departure phases. The ability to determine the distance enhances the pilot's situational awareness and contributes to safer flight planning and execution. Thus, DME is integral to utilizing VOR navigation effectively rather than using other forms of navigation or instruments mentioned in the other options.