Three out of four
The E-4B in the foreground is the one that, when this photograph was taken, is known as the "alert" plane. That means its crew is on a week-long alert and ready to go airborne within minutes, should such a situation arise. Which plane is on alert depends on many factors, among the most important of which is the maintenance schedule.
The planes are also sometimes used to flying the U.S. secretary of defense on international trips.
July 23, 2013 4:00 AM PDT
Photo by: Daniel Terdiman/CNET
| Caption by: Daniel Terdiman
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