4/20/23 

Pilot/Controller Glossary 

D 

D

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ATIS

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(See DIGITAL-AUTOMATIC TERMINAL INFORMATION SERVICE.) 

D

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ATIS [ICAO]

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(See ICAO Term DATA LINK AUTOMATIC TERMINAL INFORMATION SERVICE.) 

DA [ICAO]

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(See ICAO Term DECISION ALTITUDE/DECISION HEIGHT.) 

DAIR

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(See DIRECT ALTITUDE AND IDENTITY READOUT.) 

DANGER AREA [ICAO]

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An airspace of defined dimensions within which activities dangerous to the flight 

of aircraft may exist at specified times. 

Note: The term “Danger Area” is not used in reference to areas within the United States or any of its 

possessions or territories. 

DAS

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(See 

DELAY ASSIGNMENT

.) 

DATA BLOCK

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(See ALPHANUMERIC DISPLAY.) 

DATA LINK AUTOMATIC TERMINAL INFORMATION SERVICE (D

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ATIS) [ICAO]

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 The provision of 

ATIS via data link. 
DCT

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(See DELAY COUNTDOWN TIMER.) 

DEAD RECKONING

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 Dead reckoning, as applied to flying, is the navigation of an airplane solely by means 

of computations based on airspeed, course, heading, wind direction, and speed, groundspeed, and elapsed time. 
DEBRIS RESPONSE AREA (DRA)

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Used by ATC. Areas of airspace that may be activated in response to 

unplanned falling debris in the NAS. 
DECISION ALTITUDE/DECISION HEIGHT [ICAO Annex 6]- A specified altitude or height (A/H) 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. 

1. Decision altitude (DA) is referenced to mean sea level and decision height (DH) is referenced to the threshold 

elevation. 

2. Category II and III minima are expressed as a DH and not a DA. Minima is assessed by reference to a radio 

altimeter and not a barometric altimeter, which makes the minima a DH. 

3. The required visual reference means that section of the visual aids or of the approach area which should have 

been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change 

of position, in relation to the desired flight path. 
DECISION ALTITUDE (DA)

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 A specified altitude (mean sea level (MSL)) on an instrument approach 

procedure (ILS, GLS, vertically guided RNAV) at which the pilot must decide whether to continue the approach 

or initiate an immediate missed approach if the pilot does not see the required visual references. 
DECISION HEIGHT (DH)

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With respect to the operation of aircraft, means the height at which a decision must 

be made during an ILS or PAR instrument approach to either continue the approach or to execute a missed 

approach. 

(See ICAO term DECISION ALTITUDE/DECISION HEIGHT.) 

PCG D

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