The Boeing E-4B “Nightwatch,” often called the U.S. government’s “Doomsday plane,” has recently drawn public attention after being spotted flying toward Washington, D.C. Sightings of the rare aircraft quickly sparked speculation online due to its association with national emergencies.

The E-4B is one of four aircraft operated by the U.S. Air Force and serves as an airborne command center for senior government and military leaders. Its mission is to ensure continuity of government during extreme crises, including nuclear conflict or the loss of ground-based command facilities.

Designed during the Cold War, the aircraft is heavily hardened against electromagnetic pulses and cyber interference. It relies in part on analog systems, which are less vulnerable to digital disruption, and can remain airborne for several days using midair refueling.