IWC Schaffhausen Spitfire UTC Mode D'emploi page 25

Adjusting the hour hand and the date
22 | 23
Pull the crown to position 1. By rotating the crown, you
can now adjust the hour hand forwards or backwards in
steps of one hour. The movement is not stopped by this
operation, and the set time in minutes and seconds is
unaffected by this adjustment. If the hour hand is ad-
justed past midnight, the date will move forwards to the
next day or backwards to the previous day. This function
is used for setting the date or is required when crossing
from one time zone to another.
UTC (Universal Time Coordinated)
Regardless of the local time, UTC time is used throughout
the world as a uniform reference point for aircraft. UTC is
the time basis for worldwide operational control by the
majority of airlines and for air traffic control.
TZC (Time Zone Corrector)
Local times throughout the world are, for the most part,
divided into time zones with a time difference of exactly
one hour in each case. The functions of the TZC (Time
Zone Corrector) permit rapid adjustment of the time
display in steps of one hour.