Plain English Meaning
The radials from VOR stations that are used to draw or define a route or fix on the chart. They are the radials that 'form' the route or the crossing point.
Full Definition
The specific VOR radials used to define the boundaries of an airway, route segment, or intersection. A formation radial is one of the radials whose intersection establishes a fix, or whose centerline forms the path of a route.
Context Anchor
Seen on instrument charts and in altitude discussions where a fix controls when to climb, descend, or meet a minimum altitude.
Derivation
From 'formation' (the act of forming or shaping) and 'radial' (a line outward from a VOR station). Together: the radials that form or define the route or fix.
Why Pilots Care
Prevents altitude deviations and mid-air conflicts during formation flight under IFR.
Intuition Check
Do not read formation as meaning aircraft flying together in a formation. Here, it means the radials that form or define a navigation fix.
Example Sentence 1
The intersection is established by the formation radials from two nearby VORs crossing at a specific point.
Example Sentence 2
Altitude restrictions on the formation radials were briefed prior to departure.