Time, Military

Most U.S. civilians equate military time with the 24-hour clock, a convention for counting the hours of the day from 0 to 24, and with the expression “Zulu time,” a code for the time of day at the meridian through Greenwich, England. But for the U.S. military’s global operations, precise time is crucial to navigation, geographical positioning for locating forces and targets, and secure communications. Military time, therefore, is more than a method for counting the hours. It is also an authoritative source of time and a set of methods to disseminate synchronized time worldwide.

The key system for relating time to location information has become the Global Positioning System (GPS). GPS employs a constellation of earth-orbiting satellites, depends on precise atomic frequency standards (also known ...