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Displaying the time in a second time zone is one of the most popular complications found on fine mechanical wristwatches. Not only does it showcase the manufacturer's watchmaking expertise, it also serves a very practical purpose when you travel. Almost every luxury watch brand offers a few models equipped with this function in its lineup. Over time, several different technical solutions have been developed for these instruments, which are often referred to as GMT watches.
What Is the Point of a Second Time Zone on a Wristwatch?
Anyone traveling across time zones needs to keep a close eye on the time difference between home and their current location if they want to stay in touch with the people back home. Otherwise, they risk waking their loved ones in the middle of the night or hearing their company's voicemail announce that the office is unfortunately closed at the moment. A watch that can show the time in a second time zone alongside the current local time is extremely helpful in such situations. Beyond that, this additional function can also be useful for anyone who doesn't travel to distant countries all that often but is regularly in contact with relatives or business partners abroad.
Some fans of these dual-time complications also swear by a very particular side effect of wearing such a watch while traveling. Being able to see the time at your point of origin or destination and the current local time simultaneously is said to make adjusting to a different time zone easier and to ease unpleasant effects such as jet lag or sleep disturbances, at least a little.
Where Does the Name Come From?
The abbreviation GMT stands for "Greenwich Mean Time" and refers to the mean solar time at the Earth's prime meridian. It served as the international standard time from 1884 to 1928, but was replaced in this role by Coordinated Universal Time (UTC) as early as 1972. As a result, the term is now only commonly used in the United Kingdom and some countries in West Africa, where it refers to the Western European Time zone. For traditional reasons, however, the abbreviation still frequently appears in the model names of wristwatches that can display a second time zone, and on the models in question it is usually marked on the dial or the case. Where this is not the case, the watch's name often contains a corresponding reference.
Examples include the Carrera Calibre 7 Twin-Time from TAG Heuer and the Cellini Dual Time from Rolex.
What Types of GMT Watches Are There?
Watch connoisseurs generally don't need an explicit reference on the watch or in its name. A glance at the dial is usually enough for them to identify a dual-time watch as such. To display a second time zone, watches require – depending on the model – an additional hand and a 24-hour scale, an additional small subdial, or a rotating ring indicating the various time zones. The latter typically takes the form of city names, each of which serves as the reference city for its respective time zone.
On many models, the second time zone display also stands out thanks to distinctive color accents. On some models, such as the Breitling Avenger II GMT or the Omega Seamaster Planet Ocean GMT GoodPlanet Foundation, the additional hands are finished in a striking red or orange.
The Rolex GMT-Master II and the TAG Heuer Formula 1 Calibre 7 GMT Automatic 41 mm, by contrast, feature additional hour hands that look more understated thanks to their blue or green coloring. The corresponding 24-hour scale can be located on the bezel – as with the Formula 1 or the GMT-Master – or on the outer edge of the dial.
On other watches, such as the Hamilton Jazzmaster Traveler GMT, the Longines Heritage Avigation, or the Omega Seamaster Aqua Terra 150M GMT, the scale sits inside the regular hour markers on the dial, which is why the fourth hand is shorter on these models. Another distinctive feature of this type of watch, with a second time zone display placed on the edge of the dial or on the case, is the use of different colors to mark the daytime and nighttime hours.
This is the reason, for example, for the characteristic blue-and-red or black-and-red bezels of the GMT-Master versions, which are sometimes jokingly called the "Pepsi" or "Coke" Rolex precisely because of these color combinations.
Second Time Zone on a Subdial
Two examples of a small additional subdial that displays the second time zone with two hands are the TAG Heuer Carrera Calibre 8 GMT Automatic 41 mm and the previously mentioned Cellini Dual Time from Rolex.
In the case of a chronograph with a second time zone, the latter doesn't necessarily have to be read from one of the subdials; it can also be indicated by an additional hour hand on the main dial – as on the Omega Seamaster Aqua Terra Chronograph, for example.
A particularly exclusive example of watches that indicate the second time zone using the names of reference cities is the Breguet Classique GMT. On this model, however, the display appears in a dedicated window at 6 o'clock, so only one city name is fully visible at a time. On similar models from other manufacturers, by contrast, the names of the time zone reference cities are printed on the dial or the flange (rehaut) and are therefore always fully visible.
Watches for Pilots and Navigators: A Look at Watch History
The Rolex GMT-Master, incidentally, is considered the pioneer among watches with a second time zone. This model emerged in 1953 from a collaboration between the renowned Swiss manufacture with the crown logo and the American airline Pan American World Airways (Pan Am). It quickly became one of the most popular models worn by civil aviation pilots – and remains a favorite to this day.
Since pilots and navigators had to carry out calculations across time zones themselves until onboard computers were introduced, it comes as no surprise that a watchmaker with such strong ties to aviation as Breitling also offers numerous models with a GMT function.
Whether Avenger, Chronomat, or Navitimer – all of these Breitling classics are also available in versions with an additional hand for a second time zone. One technical challenge in developing mechanical watches with a second time zone, by the way, was making it possible to set the second time without having to stop the movement and reset the "main" time display.
For collectors of mechanical luxury watches, models with a GMT function often hold a very special appeal, as they offer an entry into the fascinating world of complications – at prices that are quite affordable compared to those of masterpieces with a perpetual calendar or tourbillon. So there are plenty of good reasons to buy a dual-time watch, even if you aren't constantly on the road – whether it's a fascination with watchmaking technology or simply the desire for a watch with a few distinctive visual touches.
