Abstract: An automatic system is provided for alerting ground personnel as to the existence of a threat to commercial aircraft in which the threat is determined by a classified system, but in which the local area network employed by the military missile warning is isolated from an unclassified local network coupled to the aircraft's transponder which transmits the threat existence and status to ground personnel. The barrier to transmitting classified information involves both filtering between the classified LAN and unclassified LAN, the use of only discrete signaling lines in the classified LAN isolated by opto-electronics to provide physical separation between the two local area networks, and communications formatting which precludes the transmission of classified information across the barrier between the classified local area network and the unclassified local area network.

Abstract: An automatic system is provided for alerting ground personnel as to the existence of a threat to commercial aircraft in which the threat is determined by a classified system, but in which the local area network employed by the military missile warning is isolated from an unclassified local network coupled to the aircraft's transponder which transmits the threat existence and status to ground personnel. The barrier to transmitting classified information involves both filtering between the classified LAN and unclassified LAN, the use of only discrete signaling lines in the classified LAN isolated by opto-electronics to provide physical separation between the two local area networks, and communications formatting which precludes the transmission of classified information across the barrier between the classified local area network and the unclassified local area network.