Caution — Page 24, Lesson 26

I want to walk you through a set of aviation abbreviations and definitions that you’ll see in charts, flight plans, and communications. These are part of the standard shorthand used by pilots and air traffic control, so let’s go through them in order. Starting with CTOT — that stands for Calculated Take-off Time. This is the precise time assigned by air traffic flow management that your aircraft must be ready to take off, usually to manage slot times at busy airports. Next, CTR is Control Zone. That’s a controlled airspace extending upwards from the surface around an aerodrome, designed to protect arriving and departing traffic. CU means Cumulus — the puffy, cotton-like cloud type. CUF is Cumuliform, which describes any cloud with a heaped, billowing shape, not just cumulus itself. CUST is simply Customs — the customs authority at an airport. CW stands for Continuous Wave. This is a type of radio transmission where a carrier wave is transmitted without modulation, often used in older Morse code or certain navigation aids. CWY is Clearway — an area beyond the runway, cleared of obstacles, that an aircraft can use during the initial climb when calculating take-off performance. Now we have the letter D with different meanings depending on context. When used as a prefix in graphics, D... means DME Range — the distance from a Distance Measuring Equipment station. When used as a suffix to a VOR or ILS frequency in graphics, D indicates DME Frequency pairing — that the VOR or ILS frequency is paired with a DME channel. When followed by an identification, D... means Danger Area — a defined airspace where hazardous activities may take place. And when used as a tendency indicator for RVR — Runway Visual Range — during the previous ten minutes, D means Downward — the visibility is decreasing. DA is Decision Altitude — the altitude on a precision approach at which you must decide to continue the approach or execute a missed approach, referenced to mean sea level. DAAIS is Danger Area Activity Information Service — a service that provides information about activity within danger areas. DACS is Danger Area Crossing Service — a service that helps aircraft cross danger areas safely. DBC is Comecon Data Bank — a data bank associated with the former Comecon economic bloc, used in some European aviation contexts. DBE is Eurocontrol Data Bank — the data bank maintained by Eurocontrol for flight planning and traffic management. DCD is Double Channel Duplex — a communication mode using two separate channels, one for transmit and one for receive, allowing simultaneous two-way communication. DCKG is Docking — the process of parking an aircraft at a gate. DCS is Double Channel Simplex — a mode using two channels but only one direction at a time, so you transmit on one and receive on the other, but not simultaneously. DCT means Direct — used in relation to flight path clearances and type of approach, meaning you’re cleared to fly directly to a point without following a published route. DDM is Difference in Depth of Modulation — a technical term used in ILS (Instrument Landing System) to measure the difference in modulation depth between the 90 Hz and 150 Hz tones, which tells the aircraft how far left or right of the localizer centerline it is. DEC is December. DECR is Decrease. DEG is Degrees — for angles or temperature. DENEB is Fog Dispersal Operations — a system used at some airports to clear fog. DEP can mean Depart or Departure, and it’s also used as a message type designator in aeronautical messages. DER is Departure End of Runway — the far end of the runway from which you begin your take-off roll. DES means Descend to or Descending to. DEST is Destination — your arrival airport. DETR is the Department of the Environment, Transport and the Regions (UK) — a former UK government department. DETRESFA — note the dagger symbol — means Distress Phase. This is the phase of an emergency where an aircraft is in grave and imminent danger and requires immediate assistance. DEV is Deviation or Deviating — a change from the planned path or clearance. DF is Direction Finding — a technique to determine the bearing of a radio signal source. DFR is Departure Flow Regulator — a system or position that manages the rate of departures from an airport. DFTI is Distance From Touchdown Indicator — a display showing how far the aircraft is from the touchdown point on the runway. DH is Decision Height — similar to Decision Altitude, but referenced to the height above the runway threshold, used on precision approaches. DIF means Diffuse — describing scattered or non-directional light or cloud cover. DIST is Distance. DIV means Divert or Diverting — going to an alternate airport. DLA is Delay or Delayed. DME — with a double-dagger symbol — is Distance Measuring Equipment, the system that gives you slant-range distance from a ground station. DNG means Danger or Dangerous. DOC is Designated Operational Coverage — the published coverage area of a navigation aid within which it meets performance standards. DOM is Domestic — within one country. DP is Dew Point Temperature — the temperature at which air becomes saturated and condensation begins. DPT is Depth — for example, depth of water or snow. DR is Dead Reckoning — a method of navigation using estimated position based on heading, speed, and time. DR... — followed by DU, SA, or SN — means Low Drifting. For example, DRDU is low drifting dust, DRSA is low drifting sand, and DRSN is low drifting snow. DRG is During. DS is Dust Storm. DSB is Double Sideband — a type of radio transmission where both sidebands are transmitted, used in some older communications. DTAM is Descend to and Maintain — an instruction to descend to a specific altitude and then level off. DTG is Date-time Group — a standard format for expressing date and time in aviation messages. DTRT means Deteriorate or Deteriorating — used for weather or visibility. DTW is Dual Tandem Wheels — a landing gear configuration with two wheels in a row on each side. DU is Dust. DUA is Dedicated User Area — a reserved portion of airspace or data for a specific user. DUC is Dense Upper Cloud — thick cloud at high altitude. DUR is Duration — a length of time. DVOR is Doppler VOR — a more accurate version of VOR (VHF Omnidirectional Range) that uses Doppler principles to reduce siting errors. And finally, DW — that’s all we have in this excerpt for that entry. These definitions are the building blocks of aviation shorthand. Every time you see one of these in a NOTAM, a flight plan, or a weather report, you’ll know exactly what it means.