Definition
The named portions of a Standard Instrument Departure (SID) or Standard Terminal Arrival (STAR) procedure. A SID is broken into a Departure Procedure segment (the initial climb out of the airport), a Common Route segment (the shared path most aircraft fly), and a Transition Route segment (the link from the common route to the en route structure). A STAR is broken into a Transition Route segment (the link from the en route structure to the common arrival path), a Common Route segment (the shared path into the terminal area), and an Arrival Procedure segment (the final portion leading to the approach environment).
Plain English
SIDs and STARs are published flight paths used to leave or arrive at busy airports. Each one is divided into named pieces: the part right after takeoff or right before approach, the shared middle part most aircraft fly, and the connecting piece that joins the procedure to the en route airway system.
Context Anchor
Seen on SID and STAR procedure charts, and when checking that the correct runway or route transition has been assigned or loaded.
Derivation
Segment comes from a Latin word meaning “a piece cut off.” That helps here because a SID or STAR is not treated as one loose line; it is divided into specific charted pieces that connect together.
Why Pilots Care
Each segment carries its own altitude and routing requirements that maintain terrain clearance, traffic separation, and compliance with the published procedure.
Analogy
Think of it like a trip made of connected road pieces: the ramp out of the parking lot, the shared highway, and the exit ramp. The whole trip works only if the correct pieces are connected in the correct order.
Intuition Check
Do not read “segments” as casual chunks of a line. In this context, the segments are specific published parts of the SID or STAR that affect what route the aircraft is expected to fly.
Example Sentence 1
After reviewing the STAR, the pilot briefed each segment in order: the transition route from the en route fix, the common route into the terminal area, and the arrival procedure leading to the approach.
Example Sentence 2
ATC cleared the aircraft direct to the next waypoint to begin the arrival segment of the STAR.