CHAPTER 9 Air Decompression
Change A 9-41
From Table 9-4, repetitive group upon arrival at 6000 feet is Group E. During 90
minutes at altitude, the diver will desaturate to Group D. From Table 9-3, sea level
equivalent depth for a 100 fsw dive is 130 fsw. From Table 9-7, residual nitrogen
time for a 130 fsw dive in Group D is 11 minutes. The diver should add 11
minutes to bottom time.
Table 9-4 can also be used when a diver who is fully equilibrated at one altitude
ascends to and dives at a higher altitude. Enter Table 9-4 with the difference
between the two altitudes to determine an initial repetitive group.
Example: Divers equilibrated at a base camp altitude of 6000 feet, fly by heli-
copter to the dive site at 10,000 feet. The difference between the altitudes is 4000
feet. From Table 9-4, the initial repetitive group to be used at 10,000 feet is Group
Altitudes above 10,000 feet can impose serious stress on the body
resulting in significant medical problems while the acclimatization
process takes place. Ascents to these altitudes must be slow to allow
acclimatization to occur and prophylactic drugs may be required. These
exposures should always be planned in consultation with a Diving
Medical Officer. Commands conducting diving operations above 10,000
feet may obtain the appropriate decompression procedures from
Diving At Altitude Worksheet. Figure 9-21 is a worksheet for altitude diving. To
determine Sea Level Equivalent Depth (SLED) and corrected decompression
stops for an altitude dive, follow these steps:
Corrections for Depth of Dive at Altitude and In-Water Stops.
Table 9-4. Repetitive Groups Associated with Initial Ascent to Altitude.