Complication · Time zones
GMT and Dual Time
Partially verifiedA display of a second time zone alongside local time.
Definition
A display of a second time zone alongside local time.
Historical origin
Driven by long-haul aviation from the mid-twentieth century, when crews needed reference time and local time together.
How it works
An additional hour hand geared to the same train shows a second zone, usually on a 24-hour scale so day and night are distinguished.
In more developed designs the local hour hand jumps independently so the wearer can change zone without stopping the watch.
Pocket watch context
Uncommon in pocket watches, which predate routine international travel.
Wristwatch context
One of the most practical modern complications, standard on pilot and traveller models.
Identification
- A fourth hand reading a 24-hour scale
- A rotatable 24-hour bezel in some designs
Servicing notes
This is specialist work. Levers, springs and cam profiles in complicated work are calibre-specific, and incorrect reassembly commonly damages parts that cannot be bought. Refer the movement to a watchmaker experienced with this mechanism.
General guidance only. Complicated mechanisms should be assessed and serviced by a qualified watchmaker or clockmaker specialist, not adjusted at home.
Related photographs
No confidently matched photograph of this subject has been found yet. These photographs show a closely related record, and are not examples of the type described on this page.
Sources & references
- de Carle, D., Watch and Clock Encyclopedia
- Britten, F. J., Old Clocks and Watches and Their Makers
- Horological Journal (British Horological Institute), technical articles
Where sources disagree, the disagreement is stated rather than resolved silently.