21国家应急空中指挥所

21.NationalEmergencyAirborneCommandPostTheE-4BisdesignedtoprovideNationalCommandAuthorities(NCA)withasurvivablecapabilitytodirectandcontrolmilitaryforcesinalllevelsofconflict,includingnuclearwar.Unlikeground-basedcommandsitesthatarevulnerabletoattack,theE-4Bhasthemobilitytoescapedirectassault.Itscommunicationssystemishardenedtowithstandthemassiveelectromagneticpulseofanuclearburst,sothatthecommunicationnetworkwillfunctionfollowinganenemyattackandenabletheNCAtodirectaretaliatory1strike2.Asaircraftoperationsandmaintenanceareself-contained,operationarepossiblefromalargenumberofcivilian,abandonedordamagedairfieldswhosenumberanddistributionfurtherincreasetheE-4B’ssurvivability.FourGeneralElectricCF6-50Eenginesgivethemodified747-200Bacertifiedmaximumtake-offgrossweightof362,874kg.ThisprovidessufficientfuelfortheE-4Btoremainairborne3for12hours