c. ASDE-3X- an ASDE-X system that uses the
ASDE-3 Surface Movement Radar.
AIRPORT SURVEILLANCE RADAR- Approach
control radar used to detect and display an aircraft's
position in the terminal area. ASR provides range and
azimuth information but does not provide elevation
data. Coverage of the ASR can extend up to 60 miles.
AIRPORT TAXI CHARTS-
(See AERONAUTICAL CHART.)
AIRPORT TRAFFIC CONTROL SERVICE- A
service provided by a control tower for aircraft
operating on the movement area and in the vicinity of
(See MOVEMENT AREA.)
(See ICAO term AERODROME CONTROL
AIRPORT TRAFFIC CONTROL TOWER-
AIRSPACE CONFLICT- Predicted conflict of an
aircraft and active Special Activity Airspace (SAA).
AIRSPACE FLOW PROGRAM (AFP)- AFP is a
Traffic Management (TM) process administered by
the Air Traffic Control System Command Center
(ATCSCC) where aircraft are assigned an Expect
Departure Clearance Time (EDCT) in order to
manage capacity and demand for a specific area of the
National Airspace System (NAS). The purpose of the
program is to mitigate the effects of en route
constraints. It is a flexible program and may be
implemented in various forms depending upon the
needs of the air traffic system.
AIRSPACE HIERARCHY- Within the airspace
classes, there is a hierarchy and, in the event of an
overlap of airspace: Class A preempts Class B, Class
B preempts Class C, Class C preempts Class D, Class
D preempts Class E, and Class E preempts Class G.
AIRSPEED- The speed of an aircraft relative to its
surrounding air mass. The unqualified term
"airspeed" means one of the following:
a. Indicated Airspeed- The speed shown on the
aircraft airspeed indicator. This is the speed used in
pilot/controller communications under the general
(Refer to 14 CFR Part 1.)
b. True Airspeed- The airspeed of an aircraft
relative to undisturbed air. Used primarily in flight
planning and en route portion of flight. When used in
pilot/controller communications, it is referred to as
"true airspeed" and not shortened to "airspeed."
AIRSTART- The starting of an aircraft engine while
the aircraft is airborne, preceded by engine shutdown
during training flights or by actual engine failure.
AIRWAY- A Class E airspace area established in the
form of a corridor, the centerline of which is defined
by radio navigational aids.
(See FEDERAL AIRWAYS.)
(See ICAO term AIRWAY.)
(Refer to 14 CFR Part 71.)
(Refer to AIM.)
AIRWAY [ICAO]- A control area or portion thereof
established in the form of corridor equipped with
radio navigational aids.
AIRWAY BEACON- Used to mark airway segments
in remote mountain areas. The light flashes Morse
Code to identify the beacon site.
(Refer to AIM.)
(See AUTOMATED INFORMATION
ALERFA (Alert Phase) [ICAO]- A situation wherein
apprehension exists as to the safety of an aircraft and
ALERT- A notification to a position that there
is an aircraft-to-aircraft or aircraft-to-airspace
conflict, as detected by Automated Problem
(See SPECIAL USE AIRSPACE.)
ALERT NOTICE- A request originated by a flight
service station (FSS) or an air route traffic control
center (ARTCC) for an extensive communication
search for overdue, unreported, or missing aircraft.
ALERTING SERVICE- A service provided to notify
appropriate organizations regarding aircraft in need
of search and rescue aid and assist such organizations
(See ALERT NOTICE.)
ALONG-TRACK DISTANCE (ATD)- The distance
measured from a point-in-space by systems using