Coordination (message type designator) — Page 24, Lesson 25

I want to walk you through the next set of definitions in the communications manual. We're looking at the Coordination message type designator, which is abbreviated as CDR. This is a standardised code used in aeronautical messages to indicate that the message is about coordination between air traffic control units. Let's go through these terms one by one. First, we have Conditional Rout, abbreviated CEU. This stands for Central Executive Unit — that's a specific organisational unit in air traffic management. Next, CF means Change Frequency to... — it's an instruction to switch to a different radio frequency. CFMU is the Central Flow Management Unit for Europe, which manages air traffic flow across the European network. CGL stands for Circling Guidance Light or Lights — these are lights that help pilots during circling approaches. CHAPI is the Compact Helicopter Approach Path Indicator — a visual aid specifically for helicopters. CH simply means Channel, referring to a radio channel. CHG is the Modification message type designator — used when a flight plan or message needs to be changed. CI stands for Cirrus, which is a type of high-altitude cloud. CIDIN is the Common ICAO Data Interchange Network — that's the network used by ICAO member states to exchange aeronautical data. CIT means Near or over large towns — a position or location reference. CIV stands for Civil, as in civil aviation. CK means Check — an instruction to verify something. CL is Centre Line, referring to the centre line of a runway or taxiway. CLA means Clear Type of Ice Formation — a meteorological term describing the type of ice that forms on aircraft. CLBR is Calibration — the process of checking and adjusting instruments. CLD is Cloud. CLG means Calling — used in radio communications to indicate you are calling a station. CLR stands for Clear or Cleared to... or Clearance — it can mean the weather is clearing, or that an aircraft is cleared to a certain altitude or route, or it can refer to an air traffic control clearance. CLSD means Close, Closed, or Closing — for example, a runway that is closed. CM is Centimetre — a unit of length. CMB means Climb to or Climbing to — an instruction to climb to a specific altitude. CMN is Control Motion Noise — a term related to aircraft handling characteristics. CMPL means Completion, Completed, or Complete — indicating that an action or procedure is finished. CNL means Cancel or Cancelled. It also appears as the Flight Plan Cancellation message type designator — used when a flight plan is being withdrawn. CNS stands for Communications, Navigation and Surveillance — the three core functions of air traffic management. Coded refers to the centre line lights of the approach light system — they are coded, meaning they flash in a specific pattern. COL means Column, as in tables and text. Colour tells us that runway centre line lights are coloured red over the final 300 metres, and alternately red and white in the penultimate 600 metres — that's the 600 metres before the last 300. COM is Communications. CONC is Concrete — a runway surface type. COND is Condition. CONS is Continuous. CONST means Construction or Constructed. CONT means Continue, Continues, or Continued. COOR means Coordinate or Coordination — the act of coordinating between units. CO-ORD stands for Geographical Coordinates — the latitude and longitude of a position. COP is Changeover Point — a defined point along an airway where pilots switch from one navigation aid to another. COR means Correct, Correction, or Corrected — it's used to indicate a corrected meteorological message, and it's also a message type designator. COSPAS is the Cosmos Rescue System from the USSR — a satellite-based search and rescue system. COT means At the Coast — a position reference. COV means Cover, Covered, or Covering — for example, cloud cover. CPL is the Current Flight Plan message type designator — used to transmit the current active flight plan between air traffic control units. CRM is the Collision Risk Model — a mathematical model used to assess the risk of mid-air collisions. CRZ means Cruise — the phase of flight after climb and before descent. CS is Cirrostratus — a high-altitude cloud type. CTA is Control Area — a controlled airspace extending upwards from a specified altitude. CTAM means Climb to and Maintain — an instruction to climb to a specific altitude and then stay there. CTC means Contact — as in contact a specific air traffic control unit. CTL is Control. CTMO is the Central Traffic Management Organisation. And CTN — that's the last one in this list — I don't have a full definition for it in this excerpt, but it would be another standard abbreviation in the communications code. These are all standardised abbreviations used in aeronautical communications and flight planning. Each one has a precise meaning so that messages are clear and unambiguous between pilots and controllers.