The E-4 has a top speed of 969 kilometers per hour, can fly for twelve hours before it needs to be refueled (on the ground or in the air). Its only limit to remaining airborne is its oil lubricant for the engines. But that does not limit the E-4B from flying to any point on the planet, non-stop. The E-4B maintains a wide variety of communications gear, both for communication with military forces and for broadcasting messages to the public via radio or telephone systems. Each plane also carries the equivalent to the White House situation room. It has three times the floor space of the older EC-135 Looking Glass aircraft, which were retired in 1998. The E-4Bs, which cost about a quarter billion dollars each (in current dollars), are loaded with communications gear, and are designed to survive the effects of a nuclear blast while airborne (it is hardened against electromagnetic pulse and the thermal effects of a nuclear weapon). It can carry up to 114 people. Of the four aircraft, one is always kept ready at all times, usually in a position near where the President and/or Secretary of Defense are. The others are usually based in a Nebraska air Force base.
There are other aircraft in the doomsday force. These are the sixteen E-6B Mercury aircraft, which cost $142 million each. These were originally designed to provide secure communications for the Navys force of ballistic missile subs (SSBNs). The E-6Bs are modified 707s procured in the early 1990s to replace the older EC-130 TACAMO aircraft. E-6Bs have a top speed of 981 kilometers per hour, and can loiter for six hours after flying 12,144 kilometers. These aircraft have a crew of 14, and average about 95 hours of flight time a month. Like the E-4B, the E-6B can be refueled in the air. These aircraft carry an Airborne Command Post (ABNCP) and large communications suite, including SATCOM, MILSTAR, and VLF systems. They are deployed to three alert bases (in Maryland, Nebraska and California), while the main operating base is in Oklahoma.
These are aircraft that have constantly stayed on alert, ready for doomsday. To date, they have not carried out that mission. These planes have, since the end of the Cold War, been detailed at times to regional commanders or to the Federal Emergency Management Agency (FEMA). Harold C. Hutchison (firstname.lastname@example.org)
Secretary of Defense Donald Rumsfelds airplane of choice when he is on long trips away from the United States is the E-4B National Airborne Operations Center. Originally introduced in 1974 as the E-4A National Emergency Airborne Command Post. This modified 747 is the doomsday plane intended to serve as an airborne command post in the event the nukes started flying. Rumsfeld has chosen this plane to not only keep in touch with his experts, but also to cut down on travel time. The ability to refuel in mid-air has saved as much as a day of travel during some long-distance trips. It takes two KC-135 tankers to fully refuel an E-4B, and this is often done on very long, non-stop flights.