Avionics
Basic

DME Slant Range Correction

DME measures the direct (slant) distance to the beacon; the true ground distance is found by removing the height component.

Formula

d=Ds2−h2d = \sqrt{D_s^2 - h^2}

Variables

dGround distance
D_sDME slant range
hHeight above the station

Example

Slant 10 nm, 6076 ft (1 nm) high: d = √(10²−1²) ≈ 9.95 nm

Did You Know?

Directly overhead a DME station the slant range equals your altitude, so the cockpit reads your height above the beacon rather than zero — the classic “slant-range error”.

dmeslant rangedistance measuringnavigation

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