Definition
A mathematical error-detection method applied to navigation database files to verify that the data has not been altered or corrupted between the database provider and the avionics in the aircraft. The provider runs a calculation across the data and stores the resulting value with the file; the receiving system runs the same calculation when the data is loaded and compares the result. If the two values match, the data is accepted as intact. If they differ, the data is rejected.
Plain English
A built-in check that confirms the navigation data loaded into your avionics is exactly the same as what the database provider sent, with nothing missing, changed, or corrupted along the way.
Context Anchor
Seen in discussions of navigation database quality, database loading, and the work done by database providers before data is used by avionics.
Derivation
‘Cyclic’ refers to the repeating mathematical operation used in the check. ‘Redundancy’ means extra information added to the data — not for content, but for verification. ‘Check’ is the comparison step. Together: an extra calculated value, produced by a repeating process, used to check that the data is intact.
Why Pilots Care
Confirms that approach, departure, and enroute data remain accurate, preventing navigation errors from corrupted files.
Analogy
A CRC is like a tamper check on a sealed package. It does not tell you everything inside the package, but it can show that the package is not in the same condition it was expected to be in.
Intuition Check
A CRC does not correct the database by itself. It is mainly a warning method that tells the system whether the data still matches the expected data.
Example Sentence 1
When the new navigation database was loaded, the avionics ran a CRC and confirmed the file was intact before allowing it to be used for flight.
Example Sentence 2
A CRC mismatch during database update halts the process and alerts the crew to reload the data.