Aeronautical Terms beginning with D
D.C.
Direct Current.
DA
Decision Altitude.
DACS
Digital Aeronautical Chart Supplement
Database Identifier
A specific geographic point in space identified on an aeronautical chart and in an aviation database, officially designated by the controlling state authority or derived by Jeppesen. It has no ATC function and should not be used in filing flight plans nor used when communicating with ATC.
DBRITE
Digital Bright Radar Indicator Tower Equipment
Deceleration error
A magnetic compass error that occurs when the aircraft decelerates while flying on an easterly or westerly heading, causing the compass card to rotate toward South.
Decision Altitude (DA)
A specified altitude in the precision approach at which a missed approach must be initiated if the required visual reference to continue the approach has not been established. The term Decision Altitude (DA) is referenced to mean sea level and the term Decision Height (DH)is referenced to the threshold elevation. Even though DH is charted as an altitude above MSL, the U.S. has adopted the term DAas a step toward harmonization of the United States and international terminology. At some point, DA will be published for all future instrument approach procedures with vertical guidance.
Decision height (DH)
A specified height above the ground in an instrument approach procedure at which the pilot must decide whether to initiate an immediate missed approach if the pilot does not see the required visual reference, or to continue the approach. Decision height is expressed in feet above ground level.
Deice
The act of removing ice accumulation from an aircraft structure.
Delay Indefinite (Reason If Known) Expect Further Clearance
Used by ATC to inform a pilot when an accurate estimate of the delay time and the reason for the delay cannot immediately be determined; e.g., a disabled aircraft on the runway, terminal or center area saturation, weather below landing minimums, etc.
Departure End of Runway (DER)
The end of runway available for the ground run of an aircraft departure. The end of the runway that is opposite the landing threshold, sometimes referred to as the stop end of the runway.
Departure procedure (DP)
Preplanned IFR ATC departure, published for pilot use, in textual and graphic format.
DER
Departure End of The Runway
Descend Via
A descend via clearance instructs you to follow the altitudes published on a STAR. You are not authorized to leave your last assigned altitude unless specifically cleared to do so. If ATC amends the altitude or route to one that is different from the published procedure, the rest of the charted descent procedure is canceled. ATC will assign you any further route, altitude, or airspeed clearances, as necessary.
Deviation
A magnetic compass error caused by local magnetic fields within the aircraft. Deviation error is different on each heading.
Deviations
A. A departure from a current clearance, such as an off course maneuver to avoid weather or turbulence.
B. Where specifically authorized in the CFRs and requested by the pilot, ATC may permit pilots to deviate from certain regulations.
DF Approach Procedure
Used under emergency conditions where another instrument approach procedure cannot be executed. DF (Direction Finding) guidance for an instrument approach is given by ATC facilities with DF capability.
DGPS
Differential Global Positioning System.
DH
Decision Height
Differential Global Positioning System (DGPS)
A system that improves the accuracy of Global Navigation Satellite Systems (GNSS) by measuring changes in variables to provide satellite positioning corrections.
Digital ATIS (D-ATIS)
An alternative method of receiving ATIS reports by aircraft equipped with datalink services capable of receiving information in the cockpit over their Aircraft Communications Addressing and Reporting System (ACARS) unit.
Direct indication
The true and instantaneous reflection of aircraft pitch-and-bank attitude by the miniature aircraft, relative to the horizon bar of the attitude indicator.
Direct User Access Terminal System (DUATS)
A system that provides current FAA weather and flight plan filing services to certified civil pilots, via personal computer, modem, or telephone access to the system. Pilots can request specific types of weather briefings and other pertinent data for planned flights.
Distance circle
The circle depicted in the plan view of an IAP chart that typically has a 10 NM radius, within which chart the elements are drawn to scale. (also, reference circle)
Distance measuring equipment (DME)
A pulse-type electronic navigation system that shows the pilot, by an instrument-panel indication, the number of nautical miles between the aircraft and a ground station or waypoint.
Diverse Vector Area (DVA)
An airport may establish a diverse vector area if it is necessary to vector aircraft below the minimum vectoring altitude to assist in the efficient flow of departing traffic. DVA design requirements are outlined in TERPS and allow for the vectoring of aircraft immediately off the departure end of the runway below the MVA.
DME
Distance Measuring Equipment.
DME arc
A flight track that is a constant distance from the station or waypoint.
DME/N
Standard DME
DME/P
Precision DME
Doghouse
A turn-and-slip indicator dial mark in the shape of a doghouse.
Domestic Reduced Vertical Separation Minimum (DRVSM)
Additional flight levels between FL 290 and FL 410 to provide operational, traffic, and airspace efficiency.
Double gimbal
A type of mount used for the gyro in an attitude instrument. The axes of the two gimbals are at right angles to the spin axis of the gyro, allowing free motion in two planes around the gyro.
DP
Departure Procedure.
DPs
Departure Procedures
Drag
The net aerodynamic force parallel to the relative wind, usually the sum of two components: induced drag and parasite drag.
Drag curve
The curve created when plotting induced drag and parasite drag.
Drift Angle
Angle between heading and track.
DRT
Diversion Recovery Tool
DRVSM
Domestic Reduced Vertical Separation Minimums
DSR
Display System Replacement
DUATS
Direct User Access Terminal System (shut down May 16, 2018).
Duplex
Transmitting on one frequency and receiving on a separate frequency.
DVA
Diverse Vector Area
DVRSN
Diversion
Dynamic Magnetic Variation
A field which is simply a computer model calculated value instead of a measured value contained in the record for a waypoint.
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