Youneverseehimbutthey'rewithyoueverytimeyoufly.Theyrecordwhereyouaregoinghowfastyou'retravelingandwhethereverythingonyourairplaneisfunctioningnormally.Theirabilitytoendurealmostanydisastermakesthemsee
Youneverseehimbutthey'rewithyoueverytimeyoufly.Theyrecordwhereyouaregoinghowfastyou'retravelingandwhethereverythingonyourairplaneisfunctioningnormally.Theirabilitytoendurealmostanydisastermakesthemseemlikesomethingoutofacomicbook.They'reknownastheblackbox.
WhenplanesfallfromtheskyasaYemeniairlinerdidonitswaytoComorosIslandsintheIndiaoceanonJune302009theblackboxisthebestbetforidentifyingwhatwentwrong.SowhenaFrenchsubmarine(潜水艇)detectedthebox'shomingsignalfivedayslaterthediscoverymarkedahugesteptowarddeterminingthecauseofatragedyinwhich152passengerswerekilled.
In1958AustralianscientistDavidWarrendevelopedaflight-memoryrecorderthatwouldtrackbasicinformationlikealtitudeanddirection.ThatwasthefirstmodeforablackboxwhichbecamearequirementonallU.S.commercialflightsby1960.Earlymodelsoftenfailedtowithstandcrasheshoweversoin1965theboxwascompletelyredesignedandmovedtotherearoftheplane–thearealeastsubjecttoimpact–fromitsoriginalpositioninthelandingwells(起落架舱).ThesameyeartheFederalAviationAuthorityrequiredthattheboxeswhichwereneveractuallyblackbepaintedorangeoryellowtoaidvisibility.
Modernairplaneshavetwoblackboxes:avoicerecorderwhichtrackspilots'conversationsandaflight-datarecorderwhichmonitorsfuellevelsenginenoisesandotheroperatingfunctionsthathelpinvestigatorsreconstructtheaircraft'sfinalmoments.Placedinaninsulated(隔绝的)caseandsurroundedbyaquarter-inch-thickpanelsofstainlesssteeltheboxescanstandmassiveforceandtemperaturesupto2000℉.Whensubmergedthey'realsoabletoemitsignalsfromdepthsof20000ft.ExpertsbelievetheboxesfromAirFranceFlight447whichcrashednearBrazilonJune12009areinwaternearlythatdeepbutstatisticssaythey'restilllikelytoturnup.Intheapproximately20deep-seacrashesoverthepast30yearsonlyoneplane'sblackboxeswereneverrecovered.
【小题1】Whatdoestheauthorsayabouttheblackbox?
A．Itisanindispensabledeviceonanairplane. B．Theideaforitsdesigncomesfromacomicbook.C．Itsabilitytoavoiddisaste