Pilot/Controller Glossary  8/15/19  A  ACLT- (See ACTUAL CALCULATED LANDING TIME.)  AAI- (See ARRIVAL AIRCRAFT INTERVAL.)  AAR- (See AIRPORT ARRIVAL RATE.)  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.)  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.  ACROBATIC FLIGHT [ICAO]- Maneuvers inten- tionally performed by an aircraft involving an abrupt  change in its attitude, an abnormal attitude, or an  abnormal variation in speed.  (See RUNWAY IN USE/ACTIVE RUNWAY/DUTY  RUNWAY.)  (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.  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.  ABORT- To terminate a preplanned aircraft  maneuver; e.g., an aborted takeoff.  (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.  ACC [ICAO]- (See REQUIRED NAVIGATION  PERFORMANCE.)  ACTUAL NAVIGATION PERFORMANCE  (ANP)- ACTIVE RUNWAY- 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.)  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.  PCG A-1 