Throughout the Persian Gulf War, television reporters kept telling US viewers what time it was locally in Saudi Arabia. They did that so their audience wouldn’t get confused about who was doing what to whom, when. The whole thing would have been easier if everybody simply had used Greenwich Mean Time or, in military parlance, “Zulu Time.”
That international time system was created precisely to solve such problems. As Zulu Time evolved, the world also acquired a better navigation system, a more reliable timepiece, and far more sensible railroad timetables.
Before all that could happen, somebody first had to break the natural day into identifiable parts. For that, we may well have to thank the forebears of today’s Iraqis. While the rest of the world was still counting on fingers and doing base-ten arithmetic, the ancient Mesopotamians fell in love with the number sixty–no one knows why–and used it to divide all sorts of things. By the time Mesopotamia became Iraq, the world was stuck with the twelve-month year (one-fifth of sixty), the twenty-four-hour day, the sixty-minute hour, the sixty-second minute, and the rest of it. Once you had the numbers, you could keep time with a sundial, an hourglass, a pendulum, any number of things. If you needed to be precise, you could check your local observatory. That worked fine for several centuries. Then another problem came up.
People emerged from the Middle Ages with a more powerful yen to travel and took to the sea in large numbers. For a while, they just wandered around, not caring too much when they got home, but before long ships were hauling goods between the continents. As this import-export business grew more competitive, traders needed to know more than just which way was home. They had to know where they were at any given time and how to get where they were going by the shortest route.
European astronomers worked out a navigation system. In 1675, King Charles II built a major new observatory at Greenwich, England, and set it to turning out star charts. With enough of those charts, a navigator could find his longitude and latitude any place in the world and keep to a precise course. All he needed was a sextant and a good clock.
What Was Missing
The bad news was that, though the Europeans had plenty of sextants, nobody had yet invented a really accurate timepiece. Ships still were getting lost at sea, sometimes permanently. By 1714, things were so bad that the British government offered a reward of £20,000 sterling to anyone who could produce a state-of-the-art, reasonably accurate timepiece.
A mechanic named John Harrison came up with a chronometer that, after making a trip to Jamaica, was found to be “off” by a mere five seconds. The British government accepted it. Modern maritime navigation was off and running.
With one thing and another, however, it took Harrison forty years to collect his prize money, and it wasn’t long afterward that world travelers faced another problem that the best of watches couldn’t solve.
In the early 1830s, steam-driven trains were introduced in Britain and the United States. Soon goods and people were moving around faster than ever before, and the railroads were knitting together hundreds, perhaps thousands, of villages.
The hitch was that all of these burgs and hamlets kept their own time. An 1841 timetable for Britain’s Great Western Railroad told bewildered passengers the following: “London time is kept at all stations, which is about four minutes earlier than Reading time, five and one-half minutes before Steventon time, seven and one-half minutes before Cirencester time, and fourteen minutes before Bridgewater time.”
As the railroads expanded, things got worse. By 1880, railroad companies around the world had laid more than 150,000 miles of track. Railroads in the United States alone were dealing with more than 100 separate time schemes. In 1883, Canadian and US railroad companies worked out a system to relieve the situation. One year later, the plan was adopted by an international conference.
The plan divided the Earth into twenty-four time zones, demarcated by meridians fifteen degrees apart. France wanted Paris to be the starting line. The Americans promoted Washington. However, because Britain still ruled the waves, and much else besides, the time-organizers finally agreed to run the Prime Meridian through the old observatory at Greenwich.
Standard Time Gets Airborne
By the time the Wright brothers took to the air, standard time was used in most of the civilized world. The Wrights’ first flights were too short to make full use of the system. Twenty years later, however, two Army Douglas World Cruisers circled the Earth, and global aviation was in business. The value of the standard time system became apparent.
As aviation shrank the globe, accurate navigation became even more vital. Over land, pilots could follow highways and railroad tracks; by the mid-1920s, they even had a system of lighted airways and radio beacons. However, flying in bad weather and over water was quite another story. Most pilots weren’t trained to cope.
Early in the 1930s, the US Army Air Corps created a unit at Bolling Field near Washington, D. C., to study the problem. It hired Harold Gatty, a navigator just back from a worldwide flight, as an advisor. Most of the needed tools were at hand. The Germans had developed an aerial sextant. Accurate drift meters had appeared soon afterward, along with slide rules for solving course and distance problems. The mariners’ star charts had been adapted to aerial almanacs. The Army had watches as accurate as the big shipboard chronometers. The trick was to teach flyers to use the stuff.
The Air Corps set up a navigation training program for pilots and later expanded it into a full five-month course for navigators. At the heart of the new air training was a centuries- old technique. It amounted to drawing a scale model of the plane’s course and airspeed and adding a line to represent wind speed “and direction. From that, the navigator could figure his heading, ground speed, and time of arrival. Originally it was called “deduced reckoning,” but the first word was abbreviated to “ded,” and the phonetic pronunciation “dead reckoning ” became the accepted term.
The process involved taking repeated position readings using everything from maps to celestial observation. Celestial fixes were made using star charts based on Greenwich Mean Time. The Army Air Forces adopted it not only for navigation but also for timing its worldwide operations. World War II navigators lived by it. Their premission “time hacks” took on the solemnity of religious rituals, and GMT bound the faithful together like some secret password. Army Air Forces navigators from Italy to the Far East could tell you to the second what time it was in that little town near London.
Since the war, technology has taken much of the drudgery out of navigation, and in many aircraft, black boxes have replaced human navigators altogether. Some systems even take their celestial “fixes” from man-made satellites rather than from the stars.
Time systems themselves have gone through a series of changes. Until well into this century, Greenwich Mean Day began at noon because astronomers didn’t want to change dates during their overnight vigils. That practice confused other people, but it was not until the 1920s that the schedule was revised. The stargazers still kept their system but renamed it Greenwich Mean Astronomical Time. The rest of us went on a midnight-to-midnight routine. Officially it is “Universal Time,” but most people continue to call it GMT or use the local British equivalent, “Greenwich Civil Time.”
Zero, Zebra, Zulu
As is typical of the military, it coined its own term. Since Greenwich is the site of the “zero meridian,” they called GMT “Zero Time” or simply “Z- Time.” In the phonetic alphabet that the flyers of the time used to make themselves understood on their radios, “Z” became “Zebra.” When the alphabet was changed, the call sign became “Zulu.”
Zulu Time no longer emanates from Charles II’s old observatory. In 1958, the Greenwich astronomers moved to the English coast to escape London’s fog and city lights. They still correct their observations to show the time at the Greenwich meridian, but the old building there has been converted to a museum.
Nor are the 1884 time zones still the neat parallel lines we envision. They wiggle around international borders and state boundaries and are redrawn every now and then. When US time lines were changed in 1963, they moved several west Texas towns into the Central Time Zone, where they are an hour ahead of parts of New Mexico that are farther east. In some countries, the time zones are based on half-hour differences from GMT. A few nations have not adopted standard time.
Some scientists and chronologists would like to dump the old, Mesopotamian system of keeping time and come out with metric clocks. Some firebrands proposed that change during the French Revolution, when the populace was trying to get rid of everything aristocratic, including the timepieces. They didn’t succeed. Later drives didn’t get any further.
Some sociologists think we already may have gone too far just by introducing digital clocks. If they take over completely, whole generations could grow up without ever seeing an analog clock face. They wouldn’t know what the gunner in an old war movie was talking about when he said, “Bandits at ten o’clock high!”
We’re probably in no immediate danger of going metric or all-digital, but there have been many subtler changes in the basic units of time. For centuries, for example, the second was the smallest division of the solar day. Then scientists discovered that electrical currents make quartz crystals oscillate at regular rates. Now atomic clocks use the natural resonance of cesium atoms to divide time even more finely, cutting it into millionths and billionths of a second.
Wait until somebody comes out with a powerplant able to kick a spacecraft along at close to the speed of light. At that speed, Albert Einstein maintained and subsequent experiments confirmed, your atomic Timex should slow to a crawl and your biological clock along with it. If Einstein was right, you could come back from a lengthy trip into the cosmos to find yourself younger than your grandchildren.
Chances are, if that happens, some operations type will be hanging around to make sure you close out your log on Zulu Time.
Bruce D. Callander is a regular contributor to AIR FORCE Magazine. Between tours of active duty during World War II and the Korean War, he earned a B.A. in journalism at the University of Michigan. In 1952, he joined Air Force Times, becoming editor in 1972. His most recent article for AIR FORCE Magazine, “The Sartorial Splendor of the Air Force That Was,” appeared in the June 1991 issue.
FAQs
Why does the military use Zulu time? ›
The U.S. military still uses Zulu time in its radio transmissions and documentation because of the confusion that can result when trying to coordinate activities with other countries that use different time standards. Zulu time eliminates this confusion by providing a single standard that can be applied universally.
Why do they call it Zulu time? ›Since Greenwich is the site of the “zero meridian,” they called GMT “Zero Time” or simply “Z- Time.” In the phonetic alphabet that the flyers of the time used to make themselves understood on their radios, “Z” became “Zebra.” When the alphabet was changed, the call sign became “Zulu.”
Is GMT the same as Zulu time? ›Prior to 1972, this time was called Greenwich Mean Time (GMT) but is now referred to as Coordinated Universal Time or Universal Time Coordinated (UTC). It is a coordinated time scale, maintained by the Bureau International des Poids et Mesures (BIPM). It is also known as "Z time" or "Zulu Time".
Where does Zulu time start? ›Dubbed Zulu Time, this constant clock is officially the time in Greenwich, England and is also known as Greenwich Mean Time (GMT). In 1884, Greenwich was designated the point of 0 degrees longitude or the prime meridian.
Does the US military use Zulu time? ›To avoid confusion in these matters, the military uses the time in Greenwich, England, which is commonly called Greenwich Mean Time. However, the U.S. Military refers to this time zone as Zulu time. The 'zulu' comes from the fact that each time zone is given a letter designation, 'z' being the 24th.
Why do military people say Bravo Zulu? ›“Bravo Zulu” is a Naval signal, conveyed by flag-hoist or voice radio, meaning “well done;” it has also passed into the spoken and written vocabulary.
Do airlines use Zulu time? ›Why Do Pilots Use “Zulu Time”? Pilots use Zulu time to avoid confusion arising from differences in the local time. To avoid this confusion, everyone in aviation agrees to use a single 'standard' time as a reference point. This is what “Zulu time” is in the simplest possible terms.
What is the difference between Zulu time and military time? ›Military time is based on a 24-hour clock which runs from midnight to midnight. Z, or GMT time, is also based on the 24-hour clock, however, its midnight is based on midnight local time at the 0° longitude prime meridian (Greenwich, England).
Who invented Zulu time? ›Zulu comes from the US military, which assigns global time zones with letter codes. The UTC time zone carries the letter Z, which in the phonetic alphabet is expressed as “Zulu.” And saying Zulu will make you sound more like a fighter pilot.
What countries use Zulu time? ›The countries in Zulu Time Zone include London England, Dublin Ireland, some cities in Ghana, Portugal, and all of Antartica. The civilians in these countries use the 12-hour clock. So, they use Zulu time in 12-hour format. They also refer to their time zone commonly as GMT or Greenwich Mean Time.
What does 1300 Zulu mean? ›
The time one minute after 1259 is 1300 (pronounced "thirteen hundred").
Does Zulu time ever change? ›No Daylight Saving Time in Zulu Time
Daylight Saving Time (DST) is not used for Zulu or any other military time zones.
Since the NATO phonetic alphabet word for Z is "Zulu", UTC is sometimes known as "Zulu time". This is especially true in aviation, where "Zulu" is the universal standard. This ensures that all pilots, regardless of location, are using the same 24-hour clock, thus avoiding confusion when flying between time zones.
Is Zulu time 4 or 5 hours ahead? ›Zulu time (also called 'Z' time) is the meteorological equivalent of Greenwich Mean Time, the time of day in Greenwich, England (which is a 0 longitude). During Eastern Standard Time (EST), we are 5 hours behind Zulu time, and during Eastern Daylight Time (EDT), we are 4 hours behind.
What time zone does the US Navy use? ›The military uses Coordinated Universal Time or Universal Time Coordinated (UTC) and refers to UTC+00:00 as Zulu (Z).
What time zone does the US Army use? ›Uniform Time Zone is often used in aviation and the military as another name for UTC -8. Uniform Time Zone is also commonly used at sea between longitudes 127.5° West and 112.5° West.
How do I get Zulu time on my Iphone? ›Zulu Time automatically adjusts for daylight savings and your local time zone. Add a widget to your Home Screen by long pressing on your Home Screen, then tapping the "+" in the upper left corner and selecting any of the Zulu Time Widgets.
What does Tango Mike mean? ›13. What does Tango Mike mean? Answer: It means “thank you,” or specifically, “thanks much.” In 1955, many military organizations, including NATO and the U.S. military, adopted a phonetic alphabet to aid in correctly transmitting messages.
What is Bravo Charlie Foxtrot? ›The ICAO phonetic alphabet has assigned the 26 code words to the 26 letters of the English alphabet in alphabetical order: Alfa, Bravo, Charlie, Delta, Echo, Foxtrot, Golf, Hotel, India, Juliett, Kilo, Lima, Mike, November, Oscar, Papa, Quebec, Romeo, Sierra, Tango, Uniform, Victor, Whiskey, X-ray, Yankee, Zulu.
What does tango mean soldier? ›In the NATO phonetic alphabet, established by the 1930s, the letter T is tango and became slang for target, or “enemy.” To down a target is “to shoot” them, especially when grounding an aircraft, but also “to neutralize” or “kill” them. Tango down thus means the enemy has been defeated.
What time is 0000 Zulu? ›
| UTC (Zulu) | PST/ ALDT | CDT/ EST |
|---|---|---|
| 0000* | 1600 | 1900 |
| 0100 | 1700 | 2000 |
| 0200 | 1800 | 2100 |
| 0300 | 1900 | 2200 |
The pilot (and the ATC) use the UTC (Coordinated Universal Time).
Are times in notams local or Zulu? ›Times used in the NOTAM system are Coordinated Universal Time (UTC/Zulu) unless otherwise stated, as in the body of Temporary Flight Restrictions, and must be stated in 10 digits for the year, month, day, hour, and minute (YYMMDDHHMM).
Why do pilots use Zulu time? ›Zulu time is most often used by the military, pilots, and by mariners. The reason is standardization. For the military, it is extremely important when multiple countries are coordinating across different time zones that events occur at the exact same moment.
What time is 0001 in military time? ›Speaking military time.
0001 (12:01am): “zero zero zero one” 0215 (2:15am): “zero two fifteen”
With the 2019 Fall release of the National Transportation Atlas Database (NTAD), a new map of the nation's time zones is featured, showing the geographical boundaries of four time zones in the continental U.S. and the five additional time zones used in Alaska, Hawaii and other U.S. territories.
Who runs on Zulu time? ›Zulu time is used extensively in aviation and military operations, where accurate and synchronized timekeeping is essential. Pilots and air traffic controllers use Zulu time to coordinate flight schedules and ensure that planes are operating on schedule.
What year did Zulu start? ›Zulu traces its origins to 1909, when the original founders paraded as a marching club. Between 1912 and 1914, the group had adopted an African theme for their costumes and became known as the Zulus.
What is the world standard clock? ›UTC is the time standard commonly used across the world. The world's timing centers have agreed to keep their time scales closely synchronized - or coordinated - therefore the name Coordinated Universal Time.
How long does it take to speak Zulu? ›Henning however comforts his students by telling them that it takes at least a year before one is comfortably conversational in Zulu. For those who don't have time to attend lessons, a range of self-study products are available online for sale on Learnzulu's website Learnzulu.
What is the current Zulu timestamp? ›
Current time: 14:49:40 UTC. UTC is replaced with Z that is the zero UTC offset. UTC time in ISO-8601 is 14:49:40Z. Note that the Z letter without a space.
What does 06z mean in weather? ›Common Z times are also 18Z (near noon in the U.S.) and 6Z (near midnight in the U.S.) It is always important to look at the time stamp on an image first before interpretation.
What is the last Time Zone on Earth? ›It is also referred to as the "latest time zone" on Earth, as clocks in it always show the 'latest' (i.e., most advanced) time of all time zones. UTC+14:00 stretches as far as 30° east of the 180° longitude line and creates a large fold in the International Date Line around the Pacific nation of Kiribati.
What major cities are in Zulu time? ›- Accra, Ghana.
- Reykjavik, Iceland.
- Yamoussoukro, Cote d'Ivoire (Ivory Coast)
- Lomé, Togo.
- Monrovia, Liberia.
- Bissau, Guinea-Bissau.
- Nouakchott, Mauritania.
- Dakar, Senegal.
There are 24 regions (Time Zones) around the world with a time difference of one hour. This system has been adopted internationally by setting the total time difference around the world as 24 hours.
What does Z stand for Zulu? ›All aspects of meteorology are based upon a world-wide 24-hour clock called Zulu time (Z), more commonly called Coordinated Universal Time (UTC).
What is Zulu one word answer? ›The Zulu is a tribal community mostly found in South Africa. Hence, 1st option is the correct answer. Zulu, a nation of Nguni-speaking people in KwaZulu-Natal province, South Africa.
How is Zulu time written? ›A timestamp in Zulu format would look like TZ. That is a date “YYYY-MM-DD” with the four-digit Year, two-digit month and two-digit day, “T” for “time,” followed by a time formatted as “HH:MM:SS” with hours, minutes and seconds, all followed with a “Z” to denote that it is Zulu format.
What is 12Z in weather? ›The most common Z times you will come across are 0Z (late afternoon in US), 18Z (near noon in US), 12Z (morning in US) and 6Z (near midnight in US).
Why is J omitted in Zulu time? ›The system originates with Nathaniel Bowditch's 1802 American Practical Navigator where time zones were labelled with letters: the letter "J" was skipped to avoid confusion with "I" (as was the custom of the time) and because some alphabets don't have one (such as Cyrillic).
Is Zulu time on the prime meridian? ›
This means you advance the clock 24 hours, or one day on the calendar. Moving east across the International Date Line means subtracting 24 hours from the clock, thereby reversing one day on the calendar. The 24-hour clock (Z-time) begins at midnight (00Z) at this prime meridian.
What is 2030 zulu time? ›20:30 UTC is 13:30 in your local time
Letter 'Z' in military time indicates ZULU Time Zone which is equivalent to UTC.
Why Do Pilots Use “Zulu Time”? Pilots use Zulu time to avoid confusion arising from differences in the local time. To avoid this confusion, everyone in aviation agrees to use a single 'standard' time as a reference point. This is what “Zulu time” is in the simplest possible terms.
What's the difference between military time and Zulu time? ›Military time is based on a 24-hour clock which runs from midnight to midnight. Z, or GMT time, is also based on the 24-hour clock, however, its midnight is based on midnight local time at the 0° longitude prime meridian (Greenwich, England).
What is Zulu in military code? ›Military Phonetic Alphabet Code Phrases
Charlie Mike: Continue mission. Oscar Mike: On the move. Bravo Zulu: Good job/well done.
What Time Is It in Zulu Time? Zulu has no UTC offset (UTC+0), so Zulu clock time is the same as UTC time. It is a military time zone primarily used in aviation, at sea, and in the army. Zulu is one of 25 military time zones and borders Alpha in the east and November in the west.
How many countries use Zulu time? ›The countries in Zulu Time Zone include London England, Dublin Ireland, some cities in Ghana, Portugal, and all of Antartica. The civilians in these countries use the 12-hour clock. So, they use Zulu time in 12-hour format.
What cities are in Zulu time? ›- Accra, Ghana.
- Reykjavik, Iceland.
- Yamoussoukro, Cote d'Ivoire (Ivory Coast)
- Lomé, Togo.
- Monrovia, Liberia.
- Bissau, Guinea-Bissau.
- Nouakchott, Mauritania.
- Dakar, Senegal.
"BZ" is widely used as shorthand vernacular amongst members of the sea services (i.e., navies, Marines, and those coast guards that are military services versus civilian agencies).
What does tango mean in military code? ›In the NATO phonetic alphabet, established by the 1930s, the letter T is tango and became slang for target, or “enemy.” To down a target is “to shoot” them, especially when grounding an aircraft, but also “to neutralize” or “kill” them. Tango down thus means the enemy has been defeated.
How do you convert Zulu to military time? ›
First, add 12 hours to 5:30 to determine your 24-hour time: 17:30 hours. Next, use a time conversion table to find the appropriate offset. In the Central Standard Time zone (Saint Louis local time) you must add six hours for standard time, but five hours for daylight-saving time.