C  BC —back course  BCA —benefit/cost analysis  BCN —beacon  BCR —benefit/cost ratio  BDAT —digitized beacon data  BERM —snowbank(s) containing earth/gravel  BLW —below  BMP —best management practices  BND —bound  BOC —Bell Operating Company  bps —bits per second  BRG —bearing  BRI —basic rate interface  BRITE —bright radar indicator terminal equipment  BRL —building restriction line  BUEC —back-up emergency communications  BUECE —back-up emergency communications equipment  BYD —beyond  C/S/S/N —capacity/safety/security/noise  CAA —civil aviation authority; Clean Air Act  CAAS —Class A Airspace  CAB —civil aeronautics board  CARF —Central Altitude Reservation Facility  CASFO —Civil Aviation Security Office  CAT —category; clear-air turbulence  CAU —Crypto Ancillary Unit  CBAS —Class B airspace  CBI —computer based instruction  CBSA —Class B surface area  CC&O —customer cost and obligation  CCAS —Class C Airspace  CCC —Communications Command Center  CCCC —staff communications  CCCH —central computer complex host  CCLKWS —counterclockwise  CCS7-NI —Communication Channel Signal-7-Network  Interconnect  CCSA —Class C surface area  CCSD —Command Communications Service Designator  CCU —Central Control Unit  CD —clearance delivery; common digitizer  CDAS —Class D Airspace  CDR —cost detail report  CDSA —Class D surface area  CDT —controlled departure time  CDTI —cockpit display of traffic information  CEAS —Class E Airspace  CENTX —central telephone exchange  CEP —capacity enhancement program  CEQ —council on environmental quality  CERAP —center radar approach control; combined center  radar approach control  CESA —Class E surface area  CFC —central flow control  CFCF —Central Flow Control Facility  CFCS —central flow control service  CFR —Code of Federal Regulations  CFWP —central flow weather processor  CFWU —central flow weather unit  CGAS —Class G Airspace; Coast Guard Air Station  CHG —change  CIG —ceiling  CK —check  CL —centerline  CLC —course line computer  CLIN —contract line item  CLKWS —clockwise  CLR —clearance, clear(s), cleared to  CLSD —closed  CLT —calculated landing time  CM —commercial service airport  CMB —climb  CMSND —commissioned  CNL —cancel  CNMPS —Canadian Minimum Navigation Performance  Specification Airspace  CNS —consolidated NOTAM system  CNSP —consolidated NOTAM system processor  CO —central office  COE —U.S. Army Corps of Engineers  COM —communications  COMCO —command communications outlet  CONC —concrete  CONUS —Continental United States  CORP —private corporation other than ARINC or MITRE  CPD —coupled  CPE —customer premise equipment  CPMIS —consolidated personnel management information  system  CRA —conflict resolution advisory  CRDA —converging runway display aid  CRS —course  CRT —cathode ray tube  CSA —communications service authorization  CSIS —centralized storm information system  CSO —customer service office  CSR —communications service request  CSS —central site system  CTA —controlled time of arrival; control area  CTA/FIR —control area/flight information region  CTAF —common traffic advisory frequency  CTAS —center-TRACON automation system  B-3 