| ...C | Centre (preceded by runway designation number to identify a parallel runway) |
| C | Degrees Celsius (Centigrade) |
| CAA | Civil Aviation Authority |
| CAC | Circling Approach Chart |
| CAT | Category |
| CAT | Clear air turbulence |
| CAVOK | Visibility, cloud and present weather better than prescribed values or conditions |
| CB | Cumulonimbus |
| CC | Cirrocumulus |
| CDR | Conditional route |
| CDN | Coordination (message type designator) |
| CFMU | Central Flow Management Unit |
| CH | Channel |
| CHG | Modification (message type designator) |
| CI | Cirrus |
| CIDIN | Common ICAO Data Interchange Network |
| CIT | Near or over large town |
| CIV | Civil |
| CK | Check |
| CL | Centre line |
| CLA | Clear type of ice formation |
| CLBR | Calibration |
| CLD | Cloud |
| CLR | Clear or cleared to ... or clearance |
| CLSD | Close or closed or closing |
| CM | Centimetre |
| CMB | Climb to or climbing to |
| CMPL | Completion or completed or complete |
| CNL | Cancel or cancelled |
| CNL | Flight plan cancellation (message type designator) |
| CNS | Communications, navigation and surveillance |
| COM | Communications |
| CONC | Concrete |
| COND | Condition |
| CONS | Continuous |
| CONST | Construction or constructed |
| CONT | Continue or continued |
| COOR | Co−ordinate or co−ordination |
| COP | Change−over point |
| COR | Correct or corrected or correction (used to indicie corrected meteorological message |
| COV | Cover or covered or covering |
| CPDLC | Controller−pilot data link communications |
| CPL | Current flight plan (message type designator) |
| CRAM | Conditional route availability message |
| CRZ | Cruise |
| CS | Call sign |
| CS | Cirrostratus |
| CTA | Control area |
| CTC | Contact |
| CTL | Control |
| CTN | Caution |
| CTR | Control zone |
| CU | Cumulus |
| CUF | Cumuliform |
| CUST | Customs |
| CVR | Cockpit voice recorder |
| CVSM | Conventional vertical separation minimum |
| CWY | Clearway |
© 2012-21 Kristina Novotna