【Youneverseehimbutthey'rewithyoueverytimeyoufly.Theyrecordwhereyouaregoinghowfastyou'retravelingandwhethereverythingonyourairplaneisfunctioningnormally.Theirabilitytowithstandalmostanydisastermakesthem】
Youneverseehimbutthey'rewithyoueverytimeyoufly.Theyrecordwhereyouaregoinghowfastyou'retravelingandwhethereverythingonyourairplaneisfunctioningnormally.Theirabilitytowithstandalmostanydisastermakesthemseemlikesomethingoutofacomicbook.They'reknownastheblackbox.
WhenplanesfallfromtheskyasaYemeniairlinerdidonitswaytoComorosIslandsintheIndiaoceanJune302009theblackboxisthebestbetforidentifyingwhatwentwrong.SowhenaFrenchsubmarine(潜水艇)detectedthedevice'shomingsignalfivedayslaterthediscoverymarkedahugesteptowarddeterminingthecauseofatragedyinwhich152passengerswerekilled.
In1958AustralianscientistDavidWarrendevelopedaflight-memoryrecorderthatwouldtrackbasicinformationlikealtitudeanddirection.ThatwasthefirstmodeforablackboxwhichbecamearequirementonallU.S.commercialflightsby1960.Earlymodelsoftenfailedtowithstandcrasheshoweversoin1965thedevicewascompletelyredesignedandmovedtothebackoftheplane–thearealeastsubjecttoimpact–fromitsoriginalpositioninthelandingwells(起落架舱).ThesameyeartheFederalAviationAuthorityrequiredthattheboxeswhichwereneveractuallyblackbepaintedorangeoryellowtoaidvisibility.
Modernairplaneshavetwoblackboxes:avoicerecorderwhichtrackspilots'conversationsandaflight-datarecorderwhichmonitorsfuellevelsenginenoisesandotheroperatingfunctionsthathelpinvestigatorsreconstructtheaircraft'sfinalmoments.Placedinaninsulated(隔绝的)caseandsurroundedbyaquarter-inch-thickpanelsofstainlesssteeltheboxescanresistmassiveforceandtemperaturesupto2000℉.Whensubmergedthey'realsoabletoemitsignalsfromdepthsof20000ft.ExpertsbelievetheboxesfromAirFranceFlight447whichcrashednearBrazilonJune12009areinwaternearlythatdeepbutstatisticssaythey'restilllikelytoturnup.Intheapproximately20deep-seacrashesoverthepast30yearsonlyoneplane'sblackboxeswereneverrecovered.
小题1:Whatdoestheauthorsayabouttheblackbox?A.Itensuresthenormalfunctioningofanairplane.B.Theideaforitsdesigncomesfromacomicbook.C.Itsabilit
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