CHAPTER 9 Air Decompression
Change A 9-43
Determine dive site altitude by referring to a map. From Table 9-3, enter
the altitude in feet that is equal to, or next greater than the altitude at the
Enter the actual depth of the dive in feet of seawater.
Refer to paragraph 9-12.3 to correct divers depth gauge readings to actual
depths at altitude.
Read Table 9-3 vertically down the Actual Depth column. Select a depth
that is equal to or next greater than the actual depth. Reading horizon-
tally, select the Sea Level Equivalent Depth corresponding to an altitude
equal or next greater than that of your dive site.
Corrections for Equilibration.
Enter the Repetitive Group upon arrival at altitude from Table 9-4 for
the altitude listed on Line 1.
Record time in hours and minutes spent equilibrating at altitude prior to
the dive. If time at altitude is greater than 12 hours, proceed to step 7 and
Using Table 9-7, determine the Repetitive Group at the end of the pre-
dive equilibration interval.
Using Table 9-7, determine the Residual Nitrogen Time for the new
repetitive group designation from line 6 and the Sea Level Equivalent
Depth from line 3.
Enter the planned bottom time.
Add the bottom time and the residual nitrogen time to obtain the equiva-
lent Single Dive Time.
Line 10. Select the Decompression Table to be used.
Line 11. Enter the Schedule from the Decompression Table using the Sea Level
Equivalent Depth from line 3 and equivalent Single Dive Time from line
Line 12. Using the lower section of Table 9-3, read down the Table Water Stops
column on the left to the decompression stop(s) given in the Sea Level
Equivalent Depth Table/Schedule. Read horizontally to the altitude col-
umn. Record the corresponding altitude stop depths on the worksheet.
For surface decompression dives on oxygen, the chamber stops are not
adjusted for altitude. Enter the same depths as at sea level. Keeping
chamber stop depths the same as sea level provides an extra decom-