They're said to be the Air Force's indestructible last line of defense but two of four E-4B airborne command post aircraft have been taken out by the Nebraska weather. The two aircraft, based on Boeing 747-200B civilian airliners, were damaged by a tornado that hit Offutt Air Force Base on June 16. Seven RC-145 reconnaissance planes, which are Boeing 707 derivates, suffered minor damage but six were quickly returned to service. The Air Force did not detail the damage to the big planes, officially designated as the National Airborne Operations Center when they're airborne, but did confirm they have been taken off the flight line.
This is a companion discussion topic for the original entry at https://www.avweb.com/recent-updates/business-military/tornado-damages-doomsday-planes