What distance is displayed by a DME?

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Multiple Choice

What distance is displayed by a DME?

DME shows slant range—the straight-line distance from the aircraft to the DME ground station along the line of sight. It’s computed from the radio interrogation and reply timing, using the speed of light, so it naturally includes the aircraft’s altitude. Because the signal travels diagonally through space, the readout is the hypotenuse of the horizontal and vertical components, not just the horizontal ground distance. Only if you were at the same altitude as the station would slant range equal ground distance; vertical distance alone or pure horizontal distance aren’t what DME displays.

DME shows slant range—the straight-line distance from the aircraft to the DME ground station along the line of sight. It’s computed from the radio interrogation and reply timing, using the speed of light, so it naturally includes the aircraft’s altitude. Because the signal travels diagonally through space, the readout is the hypotenuse of the horizontal and vertical components, not just the horizontal ground distance. Only if you were at the same altitude as the station would slant range equal ground distance; vertical distance alone or pure horizontal distance aren’t what DME displays.

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