| C | Degrees Celsius (Centigrade); Concrete; Aircraft Category,: Crossing (Chartdesignator) |
| C | ATC |
| CAA | Civil Aeronautics Administration |
| CADIZ | Canadian Air Defence Identification Zone |
| CAR | Caribbean OCAO Region) |
| CARS | Community Aerodrome Radio Station |
| CAT | Clear Air Turbulence |
| CAT
(+number) | ILS Category
|
| CAT (+letter) | Aircraft Category |
| CCW | Counterclockwise |
| CDA | Continuous Descent Approach |
| CDI | Course Deviation Indicator |
| CDR | Conditional Route |
| CDT | Central Daylight Time |
| CEIL | Ceiling |
| CERAP | Combined Centre/Radar Approach Control |
| CFM | Confirm |
| CFP | Company Flight Plan |
| CFR | Contact Flight Rules |
| CFR | Airport Crash Fire Fighting and Rescue Services |
| CGAS | Coast Guard Air Station |
| CGL | Circling Guidance Lights |
| CH | Channel |
| CH | Critical Height |
| CHG | Changes: Modification |
| CIRCL | Circling |
| CIV | Civil |
| CL | Centre Line |
| CL | Centreline Light’s |
| CLBR | Calibration |
| CLG | Ceiling |
| CLR | Clearance. Clearance Delivery |
| CLSD | Closed |
| Cm | Centimetre |
| CMB | Climb |
| CMNPS | Canadian Minimum Navigation Performance Specification |
| CMPL | Completion: Completed; Complete |
| CNF | Computer Navigation Fix |
| CNL | Cancel or Flight Plan Cancellation Message |
| CNS | Continuous |
| CO | Country |
| COMLO | Compass Locator |
| COM | Communication/communicate |
| Comm | Communications |
| CONC | Concerning |
| CONC | Concrete |
| COND | Condition (s) |
| CONST | Construction: Constructed |
| CONT | Continuous/continue |
| COORD | Co-ordinate (s) |
| COP | Change-Over Point |
| COR | Correction/correct/corrected |
| CORR | Corridor |
| CP | Command Post |
| CPL | Current Flight Plan Message |
| Clot | Clearance (Pre-Taxi Procedure) |
| CRP | Compulsory Reporting Point |
| CRS | Course |
| C/S | Call Sign |
| CSM | Cartographic Specification Manual |
| CST | Central Standard Time |
| CS/T | Combined Station/Tower |
| CTA | Control Area |
| CTAF | Common Traffic Advisory Frequency |
| CTAM | Climb to and maintain |
| CTC | Contact |
| CTL | Control |
| CTOT | Calculated Take-off Time |
| CTN | Caution |
| CTR | Control Zone |
| CUST | Custom |
| CVFR | Controlled Visual Flight Rules |
| CVSM | Conventional Vertical Separation Minima |
| CW | Clockwise |
| C/W | Continuous Wave |
| CWY | Clearway |
| CY | Company |
