AFC  ( 1 ) Automatic Frequency Compensation.
( 2 ) Automatic Frequency Control
AFCAS Automatic.Flight.Control.Augmentation.System AFCS Automatic.Flight.Control.System AFD (.1.).Adaptive.Flight.Display..
(.2.).Advanced.Flight.Deck.. (.3.).Autopilot.Flight.Director AFDC Autopilot.Flight.Director.Computer AFDS Autopilot.Flight.Director.System AFDX Avionics.Full.Duplex.Switched.Ethernet AFEPS ACARS.Front.End.Processing.System AFI Authority Format Identifier AFIS (.1.).Airborne.Flight.Information.System. (.2.).Automatic.Flight.Information.Service AFM Aircraft.Flight.Manual AFN ATS Facilities Notification
AFS  (.1.).Aeronautical.Fixed.Service. (.2.).Airborne.File.Server.. (.3.).Automatic.Flight.System
AFSS Automatic.Flight.Service.Station AFSK Audio Frequency Shift Keying AFTN Aeronautical.Fixed.Telecommunications AFTRCC Aerospace.and.Flight.Text.Radio.Coordinating.
Council A/G Air/Ground AGACS Automatic.Ground-Air.Communication.System..It.
is.also.known.as.ATCSS.or.DATA.LINK. AGATE Advanced.General.Aviation.Transport.Experiment AGC Automatic.Gain.Control..AGC.is.used.to.maintain.
the.output.level.of.the.receiver. AGIS Air.Ground.Intermediate.System AGL Above.Ground.Level. AGS ARINC.661.Graphics.Server

AH  Alert.Height:.A.height.above.the.runway.based. on.the.characteristics.of.the.aircraft.and.its.fail. operational.landing.system,.above.which.a. Category.III.approach.would.be.discontinued.and. a.missed.approach.initiated.if.a.failure.occurred.in. one.of.the.redundant.parts.of.the.fail.operational. landing.system,.or.in.the.relevant.ground. equipment. 
AHC  Attitude.Heading.Computer:.A.computer.that.is. part.of.the.AHRS..Generates.information.for.the. pitch.and.roll.displays. 
AHRS  Attitude/Heading.Reference.Systems:.System. which.measures.and.outputs.aircraft.attitude.and. heading. 
AHS  Attitude/Heading.System:.Either.an.AHRS.or.an. IRS. 
AIDS  Aircraft.Integrated.Data.System 
AIT  Advanced.Intelligence.Tape.-.used.for.the.storage. of digital video and audio files