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When ATR decreases to 5 minutes, an alarm strikes which means that only 5 minutes
remain before your air supply will be reduced to the minimum level necessary to perform
a safe ascent, including any planned (Deep and Safety) stops and required (Deco) stops,
and still provide a tank pressure reserve upon surfacing.
When ATR decreases to 0 (min), an alarm will strike again. There is no need to panic,
calculations allow for the air you will consume while making a safe controlled ascent, in-
cluding that the stops, and still provide the surfacing tank pressure reserve.
ASCENDING TO THE SURFACE
While ascending to shallower depths, the segments that have filled up the TLBG will begin
to recede, offering a graphic representation of your multilevel diving capability.
By backing off on the TLBG (maintaining fewer segments), you can
establish a personal level of conservatism and margin of protection.
If you entered Decompression, you must not complete your ascent until the TLBG is inside
the No Decompression Zone. You should make every effort to complete all of your ascents
with the TLBG inside of the No Decompression Zone.
While you cannot provide a guarantee against the occurrence of decompression sickness,
you may choose your personal zone of caution based upon your individual age, physique,
excessive weight, training, experience, etc. to reduce the statistical risk.
(continued on page 20)
