Definition
Reporting points along an airway or flight route, depicted on aeronautical charts as solid (filled-in) triangles, at which a pilot must report position to ATC when not in radar contact.
Plain English
Specific points on your route where you are required to tell air traffic control where you are, unless ATC is already tracking you on radar.
Context Anchor
Seen on IFR route charts and used during en route position reporting, especially when ATC needs pilots to report their progress without relying on radar.
Derivation
Compulsory comes from the Latin compellere, meaning to force or require. The word signals that the report is not optional — the pilot must make it when passing the point, unless ATC has waived the requirement.
Why Pilots Care
Missing a required report can cause ATC to lose accurate flight progress data, potentially leading to traffic conflicts or delays in search-and-rescue response.
Intuition Check
Do not read “compulsory” as “recommended.” A compulsory reporting point is a required report point unless ATC has removed that requirement.
Example Sentence 1
After losing radar contact, the controller reminded the pilot to make position reports at all compulsory reporting points along the airway.
Example Sentence 2
Because the next compulsory reporting point was 50 miles ahead, the crew noted the time and fuel remaining before calling.