Plain English Meaning

A fake glideslope reading that appears higher up than the real one. The instrument shows you're on the glideslope when you're actually on a much steeper, false beam that won't bring you safely to the runway.

Full Definition

A secondary glideslope indication produced by the ILS glideslope antenna at an angle steeper than the published glide path, typically near twice the normal glide slope angle. It results from the way the glideslope signal pattern radiates and is not a usable approach reference. Pilots can avoid capturing it by intercepting the glideslope from below at the published intercept altitude.

Context Anchor

Seen during instrument approach procedures, especially when a glideslope indication appears while flying a localizer back course approach.