IWC Schaffhausen Spitfire UTC Mode D'emploi page 23

Setting the date
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If a month has fewer than 31 days, you must set the date
by hand to the first day of the following month. Release
the screw-in crown and pull it out to position 1. By rotating
it to the left, you can now move the hour hand forwards
in steps of 24 hours. You have now corrected the time dis-
play by one day while the movement continued to run.
As the hour hand passes midnight, the date is advanced
to the next day.
Setting the time and the 24-hour display
Pull the crown to position 2. The movement is stopped in
this position and with it the seconds hand. The minute
hand and the 24-hour display can now be set. The 24-
hour display can only be adjusted in combination with
the minute hand (the hour hand is set separately with the
crown in position 1). Push the crown back to position 0
to start the movement.
Important: Although the watch is water-resistant in posi-
tions 0, 1 and 2, the crown must nevertheless always be
screwed down again for normal use (position X).