( 2 ) Selector Identifier
SELCAL Selective.Calling.System..A.system.used.in. conjunction.with.HF.and.VHF.communication. systems.that.allows.a.ground-based.radio. operator.to.call.a.single.aircraft.or.group.of.aircraft. without.the.aircraft.personnel.monitoring.the.
ground station radio frequency.
SENS Sensor Sensitivity An instruction given to the TCAS equipment for
Level control.of.its.threat.volume.. Command SEPC Secondary.Electrical.Power.Contactor SEPP Stress.Evaluation.Prediction.Program SERNO Serial.Number SEU (.1.).Single.Event.Upset..
(.2.).Seat.Electronics.Unit SFAR Special.Federal.Aviation.Regulation SFDF Subsystem.Fault.Detection.Function SFE Supplier Furnished Equipment SG Signal.Generator SGML Standard.Generalized.Markup.Language. SGS Surface.Guidance.System SI (.1.).Selective.Interrogation..
(.2.).Standby.Instruments.. (.3.).Supporting.Interrogator.. (.4.).Supplementary.Information
SIAP Standard.Instrument.Approach.Procedure
SICAS Secondary.Surveillance.Radar.Improvements.and. Collision.Avoidance.System
SICASP Secondary.Surveillance.Radar.Improvements. And.Collision.Avoidance.System.Panel
SID Standard.Instrument.Departure
Sidetone The.reproduction.of.sounds.in.a.headset.(or. speaker).from.the.transmitter.of.the.same. communication.set..This.allows.a.person.to.hear. his/her.own.voice.when.transmitting.
SIF (.1.).Standard.Interchange.Format.. (.2.).System.Integration.Facility
SIGMETS Significant Meteorological Observations
SIL (.1.).Systems.Integration.Lab.. (.2.).Service.Information.Letter
Simplex A.communication.operation.that.uses.only. a.single.channel.for.transmit.and.receive. operations..Communications.can.take.place.in. only.one.direction.at.a.time.
SINAD Signal-plus-Noise-plus-Distortion.to.Noise-plus-Distortion-Ratio
SIP Single.In-line.Package
SITA Societe.Internationale.de.Telecommunications.
Aeronautiques
SITP/D System.Integration.Test.Plan/Description SIT System.Integration.and.Test SITR System.Integration.Test.Report SIU Satellite.Interface.Unit SKP Skip Skywave A radio wave that is reflected by the ionosphere.
Depending.upon.the.state.of.the.ionosphere,.the.
reflected radio wave may propagate along the layer of the ionosphere or be reflected at some
angle..It.is.also.known.as.ionospheric.or.indirect. wave.
SL Sensitivity.Level S/L Sub-Level SLA Service.Level.Agreement Slant Range The.line-of-sight.distance.from.the.aircraft.to.a.
DME.ground.station. SLC Synchronous.Link.Control SLH System.Level.Health SLI System.Level.Interface SLM Standard.Length.Message SLoC Source.Lines.of.Code SLS Side-Lobe.Suppression..A.system.that.prevents.
a.transponder.from.replying.to.the.side-lobe. interrogations.of.the.SSR..Replying.to.side-lobe. interrogations.would.supply.false.replies.to.the. ATC.ground.station.and.obscure.the.aircraft. location.
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