<item><hi format=bold>Configuration options:</hi> the E-4 is configured as an AABNCP (Advanced Airborne National Command Post); its upper deck serves as a crew rest area; the main deck holds the President (as Commander-in-Chief of US forces) and his battle staff in five compartments: the flight crew section, the NCA (National Command Authority) work area, a conference room, battle staff, and C3I (command, control, communications and intelligence) area; the aircraft is shielded against EMP
<item><hi format=bold>Advanced airborne national command post (AABNCP):</hi> the E-4B cruises typically at 580 mph (933 km/h) at 32,000 ft (9,754 m), is refueled in flight, and meets a requirement to stay aloft for 72 hours; in a nuclear war, this duration could be extended to a full week, the E-4B's sustainability aloft being limited only by oil lubricant of its engines