Pilot/Controller Glossary

4/3/14

PCG D−1

D

D-ATIS−

(See 

DIGITAL-AUTOMATIC TERMINAL

INFORMATION SERVICE

.)

DA [ICAO]−

(See ICAO Term DECISION

ALTITUDE/DECISION HEIGHT.)

DAIR−

(See DIRECT ALTITUDE AND IDENTITY

READOUT.)

DANGER AREA [ICAO]− 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−

(See 

DELAY ASSIGNMENT

.)

DATA BLOCK−

(See ALPHANUMERIC DISPLAY.)

DEAD RECKONING− 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.

DECISION ALTITUDE/DECISION HEIGHT

[ICAO]− 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.

Note 1: Decision altitude [DA] is referenced to

mean sea level [MSL] and decision height [DH] is
referenced to the threshold elevation.

Note 2: 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 HEIGHT− With respect to the operation

of aircraft, means the height at which a decision must

be made during an ILS, MLS, or PAR instrument

approach to either continue the approach or to execute

a missed approach.

(See ICAO term DECISION

ALTITUDE/DECISION HEIGHT.)

DECODER− The device used to decipher signals

received from ATCRBS transponders to effect their

display as select codes.

(See CODES.)
(See RADAR.)

DEFENSE AREA- Any airspace of the contiguous

United States that is not an ADIZ in which the control

of aircraft is required for reasons of national security.
DEFENSE VISUAL FLIGHT RULES− Rules

applicable to flights within an ADIZ conducted under

the visual flight rules in 14 CFR Part 91.

(See AIR DEFENSE IDENTIFICATION ZONE.)
(Refer to 14 CFR Part 91.)
(Refer to 14 CFR Part 99.)

DELAY ASSIGNMENT (DAS)− Delays are distrib-

uted to aircraft based on the traffic management

program parameters. The delay assignment is

calculated in 15−minute increments and appears as a

table in Traffic Flow Management System (TFMS).
DELAY INDEFINITE (REASON IF KNOWN)

EXPECT FURTHER CLEARANCE (TIME)− 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.

(See EXPECT FURTHER CLEARANCE (TIME).)

DELAY TIME− The amount of time that the arrival

must lose to cross the meter fix at the assigned meter

fix time. This is the difference between ACLT and

VTA.
DEPARTURE CENTER− The ARTCC having

jurisdiction for the airspace that generates a flight to

the impacted airport.
DEPARTURE CONTROL− A function of an

approach control facility providing air traffic control

service for departing IFR and, under certain

conditions, VFR aircraft.

(See APPROACH CONTROL FACILITY.)
(Refer to AIM.)