What is the acceptable tolerance of DME indications?

The acceptable tolerance of DME (Distance Measuring Equipment) indications is set to ensure accurate distance reporting for navigation. The standard tolerance is defined as +/- 0.5 nautical miles or 3% of the distance, whichever value is greater. This means that as the distance increases, the tolerable error can also increase, which is essential for precision in navigation, especially over longer distances.

For distances less than approximately 16.67 nautical miles (in that case, +/- 0.5 NM would apply), the tolerance is fixed. Beyond that, the percentage becomes relevant since it accounts for larger distances where a static error margin would be insufficient. By enabling a dynamic tolerance, this specification ensures that pilots have reliable distance readings, which is crucial for maintaining safe navigation during flight operations.

In contrast, the other options provide different tolerances that do not align with the established standards for DME accuracy, thus making them unsuitable for maintaining the integrity required in aviation navigation.