Plain English Meaning

An approach that uses one signal to keep you on the correct path toward the runway and a second signal that tells you exactly how far you are from the airport. Together they let you fly down to a safe minimum altitude even though there is no glide slope.

Full Definition

A non-precision instrument approach that combines a Simplified Directional Facility (SDF) for lateral course guidance with Distance Measuring Equipment (DME) for slant-range distance information from a designated ground station. The SDF provides a fixed final approach course similar to a localizer but with a wider course width (6° or 12°) and is not always aligned with the runway. DME provides continuous distance readouts that allow to , -down points, and the along the approach.