CONTROLLED TIME OF ARRIVAL- Arrival time  assigned during a Traffic Management Program. This  time may be modified due to adjustments or user  options.  CONTROLLER- (See AIR TRAFFIC CONTROL SPECIALIST.)  CONTROLLER [ICAO]- A person authorized to  provide air traffic control services.  CONTROLLER PILOT DATA LINK COMMUNICATIONS (CPDLC)- A two-way  digital communications system that conveys textual  air traffic control messages between controllers and  pilots using ground or satellite-based radio relay  stations.  CONVECTIVE SIGMET- A weather advisory  concerning convective weather significant to the  safety of all aircraft. Convective SIGMETs are issued  for tornadoes, lines of thunderstorms, embedded  thunderstorms of any intensity level, areas of  thunderstorms greater than or equal to VIP level 4  with an area coverage of $^{4}$/$_{10}$ (40%) or more, and hail  $^{3}$/$_{4}$ inch or greater.  (See AIRMET.)  (See AWW.)  (See CWA.)  (See SIGMET.)  (Refer to AIM.)  CONVECTIVE SIGNIFICANT METEOROLOG- ICAL INFORMATION- (See CONVECTIVE SIGMET.)  COOPERATIVE SURVEILLANCE- Any surveil- lance system, such as secondary surveillance radar  (SSR), wide-area multilateration (WAM), or ADS- B, that is dependent upon the presence of certain  equipment onboard the aircraft or vehicle to be  detected.  (See AUTOMATIC DEPENDENT  SURVEILLANCE-BROADCAST.)  (See NON-COOPERATIVE SURVEILLANCE.)  (See RADAR.)  (See WIDE AREA MULTILATERATION.)  COORDINATES- The intersection of lines of  reference, usually expressed in degrees/minutes/  seconds of latitude and longitude, used to determine  position or location.  COORDINATION FIX- The fix in relation to which  facilities will handoff, transfer control of an aircraft,  CROSS (FIX) AT OR ABOVE (ALTITUDE)- Used  by ATC when an altitude restriction at a specified fix  is required. It does not prohibit the aircraft from  crossing the fix at a higher altitude than specified;  however, the higher altitude may not be one that will  CROSS (FIX) AT (ALTITUDE)- Used by ATC  when a specific altitude restriction at a specified fix  is required.  CRITICAL ENGINE- The engine which, upon  failure, would most adversely affect the performance  or handling qualities of an aircraft.  CPL [ICAO]- (See ICAO term CURRENT FLIGHT PLAN.)  CPDLC- (See CONTROLLER PILOT DATA LINK  COMMUNICATIONS.)  a.  The intended direction of flight in the horizontal  plane measured in degrees from north.  b.  The ILS localizer signal pattern usually  specified as the front course or the back course.  (See BEARING.)  (See INSTRUMENT LANDING SYSTEM.)  (See RADIAL.)  COURSE- COUPLED APPROACH- An instrument approach  performed by the aircraft autopilot, and/or visually  depicted on the flight director, which is receiving  position information and/or steering commands from  onboard navigational equipment. In general, coupled  non-precision approaches must be flown manually  (autopilot disengaged) at altitudes lower than 50 feet  AGL below the minimum descent altitude, and  coupled precision approaches must be flown  manually (autopilot disengaged) below 50 feet AGL  unless authorized to conduct autoland operations.  Coupled instrument approaches are commonly flown  to the allowable IFR weather minima established by  the operator or PIC, or flown VFR for training and  safety.  COPTER- (See HELICOPTER.)  CORRECTION- An error has been made in the  transmission and the correct version follows.  or coordinate flight progress data. For terminal  facilities, it may also serve as a clearance for arriving  aircraft.  8/15/19 7/16/20  Pilot/Controller Glossary Pilot/Controller Glossary  PCG C-8 