Definition
A published arc, defined by a specified DME distance from a navigation aid, used as a transition path or holding boundary at the outer edge of a terminal arrival or approach procedure. Aircraft fly along the arc to align with the inbound course or to remain within protected airspace during sequencing.
Plain English
A curved flight path at a set distance from a ground-based navigation station, flown at the outer edge of an arrival or approach procedure to line the aircraft up for the next segment.
Context Anchor
Seen in arrival sequencing, traffic management, and air traffic control planning for busy terminal areas.
Derivation
"Outer" indicates the farther of two or more arcs in the procedure. "Fix" is a defined position in space. "Arc" comes from Latin arcus meaning bow or curve — the aircraft tracks a curved path rather than a straight line.
Why Pilots Care
Flying the arc correctly keeps the aircraft inside protected airspace and positions it for a stabilized final approach.
Analogy
It is like drawing a curved checkpoint line on a map before a busy entrance. Anyone crossing that line is noticed early so the flow can be organized before everyone reaches the same point.
Intuition Check
Fix does not mean repair here; it means a known navigation point. Outer does not mean outside controlled airspace; it means farther away from the selected fix in the traffic planning area.
Example Sentence 1
Cleared via the outer fix arc, the crew maintained 15 DME from the VOR until intercepting the inbound course.
Example Sentence 2
ATC cleared the flight direct to the outer fix to begin the arc segment of the approach.