Which operational situation requires that an aircraft must be equipped with DME?

The requirement for an aircraft to be equipped with Distance Measuring Equipment (DME) is closely tied to the use of VOR navigation systems. When pilots navigate using VOR stations, they often need to know their distance from the VOR in addition to their bearing. DME provides this essential distance information, allowing for more precise navigational guidance and situational awareness.

While VOR is a crucial part of the navigation system, the inclusion of DME enables pilots to effectively determine the exact distance to their targeted VOR station, enhancing safety and efficiency during flight. Thus, the correct operational situation that necessitates DME is directly linked to the use of VOR receivers, reinforcing the importance of this equipment in ensuring accurate navigation.

In contrast, the other options do not align with the requirements for DME. International flights may have specific navigation requirements, but DME is not universally mandated for all international operations. Uncontrolled airspace does not inherently require DME, as regulations would depend on other navigation needs. Lastly, operating below 5,000 feet does not automatically necessitate DME; rather, the requirement is closely tied to the operating procedures and systems in use, particularly VOR navigational systems.