Pilot/Controller Glossary

AAI-
(See ARRIVAL AIRCRAFT INTERVAL.)

AAR-
(See AIRPORT ARRIVAL RATE.)

ABBREVIATED IFR FLIGHT PLANS- An
authorization by ATC requiring pilots to submit only
that information needed for the purpose of ATC. It
includes only a small portion of the usual IFR flight
plan information. In certain instances, this may be
only aircraft identification, location, and pilot
request. Other information may be requested if
needed by ATC for separation/control purposes. It is
frequently used by aircraft which are airborne and
desire an instrument approach or by aircraft which are
on the ground and desire a climb to VFR-on-top.
(See VFR-ON-TOP.)
(Refer to AIM.)

ABEAM- An aircraft is "abeam" a fix, point, or
object when that fix, point, or object is approximately
90 degrees to the right or left of the aircraft track.
Abeam indicates a general position rather than a
precise point.
ABORT- To terminate a preplanned aircraft
maneuver; e.g., an aborted takeoff.
ACC [ICAO]-
(See ICAO term AREA CONTROL CENTER.)

ACCELERATE-STOP DISTANCE AVAILABLE-
The runway plus stopway length declared available
and suitable for the acceleration and deceleration of
an airplane aborting a takeoff.
ACCELERATE-STOP DISTANCE AVAILABLE
[ICAO]- The length of the take-off run available plus
the length of the stopway if provided.
ACDO-
(See AIR CARRIER DISTRICT OFFICE.)

ACKNOWLEDGE- Let me know that you have
received and understood this message.
ACL-
(See AIRCRAFT LIST.)

ACLS-
(See AUTOMATIC CARRIER LANDING
SYSTEM.)

ACLT-
(See ACTUAL CALCULATED LANDING TIME.)

ACROBATIC FLIGHT- An intentional maneuver
involving an abrupt change in an aircraft"s attitude, an
abnormal attitude, or abnormal acceleration not
necessary for normal flight.
(See ICAO term ACROBATIC FLIGHT.)
(Refer to 14 CFR Part 91.)

ACROBATIC FLIGHT [ICAO]- Maneuvers intentionally performed by an aircraft involving an abrupt
change in its attitude, an abnormal attitude, or an
abnormal variation in speed.
ACTIVE RUNWAY-
(See RUNWAY IN USE/ACTIVE RUNWAY/DUTY
RUNWAY.)

ACTUAL CALCULATED LANDING TIME-
ACLT is a flight"s frozen calculated landing time. An
actual time determined at freeze calculated landing
time (FCLT) or meter list display interval (MLDI) for
the adapted vertex for each arrival aircraft based upon
runway configuration, airport acceptance rate, airport
arrival delay period, and other metered arrival
aircraft. This time is either the vertex time of arrival
(VTA) of the aircraft or the tentative calculated
landing time (TCLT)/ACLT of the previous aircraft
plus the arrival aircraft interval (AAI), whichever is
later. This time will not be updated in response to the
aircraft"s progress.
ACTUAL NAVIGATION PERFORMANCE
(ANP)-
(See REQUIRED NAVIGATION
PERFORMANCE.)

ADDITIONAL SERVICES- Advisory information
provided by ATC which includes but is not limited to
the following:
a. Traffic advisories.
b. Vectors, when requested by the pilot, to assist
aircraft receiving traffic advisories to avoid observed
traffic.
c. Altitude deviation information of 300 feet or
more from an assigned altitude as observed on a
verified (reading correctly) automatic altitude
readout (Mode C).
d. Advisories that traffic is no longer a factor.