Pilot/Controller Glossary 

3/21/24 

CLUTTER

−

 In radar operations, clutter refers to the reception and visual display of radar returns caused by 

precipitation, chaff, terrain, numerous aircraft targets, or other phenomena. Such returns may limit or preclude 

ATC from providing services based on radar. 

(See CHAFF.) 
(See GROUND CLUTTER.) 
(See PRECIPITATION.) 
(See TARGET.) 
(See ICAO term RADAR CLUTTER.) 

CMNPS

−

 

(See CANADIAN MINIMUM NAVIGATION PERFORMANCE SPECIFICATION AIRSPACE.) 

COA

−

 

(See CERTIFICATE OF WAIVER OR AUTHORIZATION.) 

COASTAL FIX

−

 A navigation aid or intersection where an aircraft transitions between the domestic route 

structure and the oceanic route structure. 

CODES

−

 The number assigned to a particular multiple pulse reply signal transmitted by a transponder. 

(See DISCRETE CODE.) 

COLD TEMPERATURE CORRECTION

−

 A correction in feet, based on height above airport and temperature, 

that is added to the aircraft’s indicated altitude to offset the effect of cold temperature on true altitude. 

COLLABORATIVE TRAJECTORY OPTIONS PROGRAM (CTOP)

−

 CTOP is a traffic management program 

administered by the Air Traffic Control System Command Center (ATCSCC) that manages demand through 

constrained airspace, while considering operator preference with regard to both route and delay as defined in a 

Trajectory Options Set (TOS). 

COMBINED CENTER-RAPCON

−

 

An air traffic facility which combines the functions of an ARTCC and a 

radar approach control facility. 

(See AIR ROUTE TRAFFIC CONTROL CENTER.) 
(See RADAR APPROACH CONTROL FACILITY.) 

COMMON POINT

−

 A significant point over which two or more aircraft will report passing or have reported 

passing before proceeding on the same or diverging tracks. To establish/maintain longitudinal separation, a 

controller may determine a common point not originally in the aircraft’s flight plan and then clear the aircraft 

to fly over the point. 

(See SIGNIFICANT POINT.) 

COMMON PORTION

−

 

(See COMMON ROUTE.) 

COMMON ROUTE

−

 That segment of a North American Route between the inland navigation facility and the 

coastal fix. 

OR 

COMMON ROUTE

−

 

(See SEGMENTS OF A SID/STAR) 

COMMON TRAFFIC ADVISORY FREQUENCY (CTAF)

−

 A frequency designed for the purpose of carrying 

out airport advisory practices while operating to or from an airport without an operating control tower. The CTAF 

may be a UNICOM, Multicom, FSS, or tower frequency and is identified in appropriate aeronautical 

publications. 

(See DESIGNATED COMMON TRAFFIC ADVISORY FREQUENCY (CTAF) AREA.) 
(Refer to AC 90-66, Non

−

Towered Airport Flight Operations.) 

PCG C

−

6