Plain English Meaning

Specific points on an approach where you are allowed to drop down to a lower altitude — but only once you have crossed the point. Until you reach it, you must stay at or above the higher altitude shown on the chart.

Full Definition

Designated points along an instrument approach segment that allow a pilot to descend to a lower published altitude only after the aircraft has passed that point. Each step-down fix has its own minimum crossing altitude, creating a stair-shaped descent profile that keeps the aircraft safely above terrain and obstacles between the fixes.