modified from the Boeing 747-200B for the National Emergency Airborne Command Post (NEACP) program
four E-4B (3 upgraded from E-4A) are operated by 1st Airborne Command and Control Squadron of 595th Command and Control Group
E-4B - equipped with 52,500-lb CF6-50E2 engines. Has nuclear electromagnetic pulse protection, nuclear and thermal effects shielding, advanced electronics, and a wide variety of communications equipment.