Suunto D6 User Manual page 54

The STOP sign appears in the display and when you reach the depth zone between
6 m and 3 m/20 ft and 10 ft, the CEILING label, ceiling depth, and the calculated Safety
Stop time also appear in the display. You should wait until the Mandatory Safety Stop
warning disappears. The total length of the Mandatory Safety Stop time depends on
the seriousness of the ascent rate violation.
WHEN CEILING AND STOP ARE
DISPLAYED, MAKE A ONE MINUTE
MANDATORY SAFETY STOP IN THE
DEPTH ZONE BETWEEN 6 M AND 3 M.
You must not ascend shallower than 3 m/10 ft with the Mandatory Safety Stop warning
on. If you ascend above the Mandatory Safety Stop ceiling, a downward pointing arrow
will appear and a continuous beeping starts. You should immediately descend to, or
below, the Mandatory Safety Stop ceiling depth. If you correct this situation at any
time during the dive, there are no effects on the decompression calculations for future
dives.
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