KEY POINTS
  • The E-4B Advanced Airborne Command Post, or "doomsday plane," is a highly survivable flying fortress.
  • Designed during the Cold War, each plane is built to endure the immediate aftermath of a nuclear detonation.
  • "It's like a backup Pentagon," a U.S. Air Force crew member told CNBC aboard the aircraft. "There's always one plane on alert and ready to go 24 hours, seven days a week."

MARINE CORPS AIR STATION MIRAMAR, Calif. — There is nothing quite like the Air Force's E-4B aircraft.

Born and bred for battle, the modified Boeing 747s are nearly six stories tall, equipped with four colossal engines and designed to survive a nuclear attack.