Plain English Meaning

The lowest altitude and visibility you're allowed to use on an ILS approach when the glideslope isn't working or isn't being used, so you're flying with side-to-side guidance only.

Full Definition

The descent altitude and visibility values published on an ILS approach chart that apply when only the localizer (lateral guidance) is used, without glideslope (vertical) guidance. Because the approach becomes non-precision in this case, the minimum descent altitude is higher and the required visibility is typically greater than the full ILS minimums shown on the same chart.

Context Anchor

Seen on instrument approach charts, especially when the vertical guidance for an approach is unavailable or when the procedure is flown as a localizer-only approach.