This includes its communications suite. Not only does the aircraft offer satellite communications for worldwide communications, it also carries a 5-mile long spool antenna for the VLF (very low frequency) transmissions, allowing those aboard the plane to communicate directly with the nation's fleet of nuclear-armed submarines up to 3,000 miles away.

The Air Force only has four E-4B's in total with one fully-fueled on standby at all times, often within a stone's throw of Air Force One so that if the President's plane is compromised, he's got a back-up at the ready. The other three not on standby also serve a number of non-end of the world functions such as ferrying FEMA crews to natural disaster sites then acting as temporary command posts until the situation on the ground stabilizes. [The Aviationist - Defense Industry Daily - FAS 1, 2 - Boeing]