Definition
Waypoints along an instrument approach or arrival procedure that mark points where the aircraft is permitted to descend to a lower published altitude after passing them. Each step down waypoint has its own minimum crossing altitude, and the aircraft must be at or above that altitude until the waypoint is crossed.
Plain English
Points on the approach where you are allowed to come down to a new, lower altitude — but only once you have passed the point.
Context Anchor
Seen on instrument approach charts and in procedure records for approaches that descend toward the runway in stages.
Derivation
Called 'step down' because the descent profile resembles a staircase — the aircraft levels off at one altitude, then 'steps down' to the next once past the waypoint.
Why Pilots Care
These waypoints ensure obstacle clearance and keep the aircraft at the proper altitude for each segment of the approach.
Grounding Statement
As the aircraft moves toward the runway, each step down waypoint is a location where the next lower altitude becomes available.
Intuition Check
Do not read “step down” as a casual suggestion to descend whenever it seems comfortable. In this context, it means descent is tied to specific published points and published altitudes.
Example Sentence 1
After crossing the step down waypoint, the pilot descended from 3,000 feet to the next published altitude of 2,200 feet.
Example Sentence 2
Reviewing the approach plate showed two step-down waypoints with minimum altitudes that had to be met for obstacle clearance.