Plain English Meaning

The pattern of how an aircraft slows down as it flies an arrival, including where it should be at each speed. Procedures are built around the assumption that aircraft will slow down at certain points, not all at once.

Full Definition

Planned reductions in aircraft speed at specific points along an arrival or approach procedure, used by procedure designers to ensure aircraft slow down in a predictable, manageable way before reaching speed-restricted segments, fixes, or the final approach course.

Context Anchor

Seen when briefing or flying a published instrument arrival route, especially one flown with area navigation guidance.

Derivation

From Latin 'de-' (down, away) plus 'celer' (swift) -- literally 'making less swift.' A is simply the planned shape of that slowing-down distance and time.