How accurate is DME?

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Multiple Choice

How accurate is DME?

DME accuracy is governed by the signal path and the measurement tolerances. The readout is designed to be within one half mile or within 3% of the distance, whichever is greater. This means near stations, you’ll see about 0.5 NM of error, while farther away the error can grow with distance up to 3% of what you’re actually reading. An unobstructed line of sight is essential for a valid DME reading; once terrain, curvature, or other obstructions block that path, the signal may be degraded or lost, so the reading becomes unreliable. That’s why this option best matches how DME works: it’s driven by line-of-sight availability, with accuracy defined by a 0.5 NM or 3%–of–distance rule depending on how far you are.

DME accuracy is governed by the signal path and the measurement tolerances. The readout is designed to be within one half mile or within 3% of the distance, whichever is greater. This means near stations, you’ll see about 0.5 NM of error, while farther away the error can grow with distance up to 3% of what you’re actually reading. An unobstructed line of sight is essential for a valid DME reading; once terrain, curvature, or other obstructions block that path, the signal may be degraded or lost, so the reading becomes unreliable.

That’s why this option best matches how DME works: it’s driven by line-of-sight availability, with accuracy defined by a 0.5 NM or 3%–of–distance rule depending on how far you are.

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