Definition
A compulsory reporting point on an IFR enroute chart, depicted as a filled (solid black) triangle, at which a pilot operating in non-radar airspace must make a position report to ATC.
Plain English
A spot on the chart, shown as a solid black triangle, where you are required to call ATC and report your position when you are not being watched on radar.
Context Anchor
Seen on instrument charts and used when making position reports in areas or situations where air traffic control is not using radar to track the aircraft.
Derivation
The symbol is filled in (solid) to distinguish it from an open (hollow) triangle, which marks a non-compulsory reporting point. The solid fill signals that the report is mandatory.
Why Pilots Care
It ensures air traffic control maintains aircraft separation when radar coverage is unavailable.
Intuition Check
Do not read the solid triangle as just a landmark symbol. In this context, the filled-in triangle means the point is compulsory for position reporting when non-radar reporting is in effect.
Example Sentence 1
Crossing the solid triangle reporting point, the crew called Center with their time, altitude, and next fix.
Example Sentence 2
We noted the next solid triangle reporting point on the chart before entering the non-radar segment.