Military Time is Zulu Time
For scientific reasons based on increased accuracy in measuring the earth's rotation, a new timescale, called Coordinated Universal Time (UTC), was adopted 1 January 1972. UTC replaces the previous term GMT (for Greenwich Mean Time). UTC refers to each of the world's time zones as being plus time or minus time from the Prime Meridian (Longitude Zero) that passes through the Royal Greenwich Observatory, in Greenwich, England, southeast of central London. For example, New York City is located in the U.S. Eastern Standard Time (EST) zone which is UTC minus 5 hours.
The U.S. military, as well as NASA, civil aviation and others, use the letter "Z" (phonetically "Zulu") to refer to the time at the Prime Meridian. Since the military has to coordinate operations on a world-wide basis, "Zulu Time" is used at all locations.
The Department of the Navy serves as the official timekeeper for the U.S. Department of Defense as well as for the Global Positioning System (GPS) utilizing the Master Clock at the Time Service Department, U.S. Naval Observatory, Washington, DC.
Military 24 Hour Time
The military 24 hour clock system.
The military expresses time based on a 24 hour clock, not the conventional twelve hour clock used in the civilian world. There is no AM or PM, just a four digit time that can express any minute of the day. The first two numbers are the hour and the last two are the minute. Here is how it works for some example times of the day (see clock above):
| Civilian Time | Military Time | How Spoken |
|---|---|---|
| Midnight | 2400 | twenty-four hundred |
| 1 minute after midnight | 0001 | zero-zero-zero-one |
| 30 minutes after midnight | 0030 | zero-zero-30 |
| 2:00 AM | 0200 | zero-two hundred hours |
| 11:59AM | 1159 | eleven fifty-nine |
| Noon | 1200 | twelve hundred |
| 2:00PM | 1400 | fourteen hundred |
| 5:30PM | 1730 | seventeen thirty |
| 11:00PM | 2300 | twenty-three hundred |
| 11:59PM | 2359 | twenty-three fifty-nine |
The word "hours" is sometimes added to the time, e.g. "seventeen thirty hours". Zero may be spoken as "oh". On radio transmissions, all numbers will be spoken to increase clarity, e.g. "one-seven-three-zero hours" for 5:30PM.
Military Date Format
The military uses a specific format for dates, again to eliminate any possible confusion or misinterpretation. The date format is in three parts:
- The day of the month
- The month name, often abbreviated to three capitalized letters
- The year using the last two digits or four digits if the month is spelled out in full
As an example, September 4, 2005 would be expressed as 4 September 2005 or 4 SEP 05. The month abbreviation is always the first three letters of the month, usually capitalized. Most dates on Olive-Drab.com follow the military style.
