C/NO  Carrier-to-Noise Density Ratio 
CNS  Communication,Navigation,Surveillance 
CNS/A  Communications,Navigation,and Surveillance/Airborne 
CNS/ATM  Communications,Navigation,andSurveillance/Air Traffic Management 
Coasted Track  A track that is continued based on previous track characteristics in the absence of surveillance data reports (TCAS). 
CODEC  Coder/Decoder 
COMAC  ICAO’s Communications AdvisoryCommittee 
COMM  Communications 
Compass Locator  A low-powered radio beacon,used in conjunction with ILS. A compass locator has a 2-letter identifica tion and a range of at least 15 miles. 
COMP  Compressor 
CON  Continuous 
Cone of Confusion  An inverted conical shaped area extending vertically above a VOR ground facility which is void of the bear ing signal. 
Consolan  A low-frequency, keyed,CW, short baseline system using two antennas to radiate a daisy-shaped pattern for navigational aid purposes. The frequency range is in the 300-kHz region. It is in limited use today. 
Contour  Contour or iso-counter refers to a weather radar dis-play presentation that blanks the echo returns in the center of a storm cell. The area blanked out is called contour and corresponds to the return levels that exceed a predetermined threshold. 
CONUS  Contiguous United States 
Correction (SSEC)  A correction is applied to static source pressure mea surements to partly or completely correct for pres sure errors which are caused by airflow changes. It is computed as a function of Mach and altitude based on measured errors for a particular static system. 

Corrective  A resolution advisory that instructs the pilot to devi 
Advisory  ate from current vertical rate (e.g. DO NOT CLIMB 
when the aircraft is climbing). (TCAS) 
COTS  Commercial Off-The-Shelf 
CPA  Closest Point of Approach 
CPC  (1) Cabin Pressure Controller 
(2) Cursor Position Control 
CPCI  Computer Program Configuration Item. A CPCI num-
ber identifies the configuration of a computer soft-
ware program. 
CPDLC  Controller-Pilot Data Link Communications 
CPE  Circular Position Error 
CPI  Continuous Process Improvement 
CPM  Core Processor Module 
CPN  Collins Part Number 
CPRSR  Compressor