Following is a list of tips to remember when Altitude Diving.
1. Any dive between 1000 feet and 10,000 feet is an Altitude Dive
2. There is relatively little test data for altitude diving, flying after diving or driving to altitude after diving.
3. At sea level, the diver is surrounded by one atmosphere of pressure. At 10,000 feet, the pressure is .714 atmospheres (a 30% decrease in pressure). This is the same pressure change as 10 feet of seawater, which we know makes a big difference in our no-decompression limits. As we’ll see, this must be accounted for when using the RDP or any other dive table or dive computer.
4. Besides decompression sickness, there are heightened concerns for Hypoxia and Hypothermia when divng at Altitude.
5. Unless the actual depth is converted to a theoretical depth for table use and special procedures are followed, at altitude the pressure ratio can exceed the maximum limit intended by the table or dive computer, increasing the possibility of decompression sickness.
6. There are several equipment considerations when diving at altitude: (1) Air, trapped inside the cells of a wetsuit, expands at altitude, possibly making you more buoyant. Do a buoyancy check. (2) Different Gauges act differently at altitude, check with your gauge manufacturer and know what kind of gauge you have and how altitude effects it. (3) Computers either automatically adjust for altitude, need to be manually adjusted for altitude or have no adjustment for altitude. Know your computer!
7. When using an RDP or Table to plan your dive, consult the Theoretical Depth Conversion chart first and plan your dive using your theoretical depth, not your actual depth. Adjust your safety stop accordingly.
8. Ascend from depth on an altitude dive at a rate not to exceed 30 feet per minute. Safety stops are mandatory on all dives.
9. Make no more than two dives per day when diving altitude.
10. When arriving at altitude, wait 6 hours for your body to acclimitize or adjust your dive profiles to account for the residual nitrogen in your system as a result of the increase in altitude. When diving above 8000 feet, always wait 6 hours.
11. When using charts and tables, always round conservatively - whether it be up or down.
12. Consult your certification agency or Divers Alert Network for recommendations on altitude or flying after diving. It is generally recommended not to increase your altitude more than 2000 feet for a period of 24 hours after diving.
13. Do not make repetitive dives at different altitudes. Always wait a minimum of 6 hours when diving between altitudes.
14. If you are diving at altitude, seek proper training and get certified. Tip sheets and articles found on the Internet are no substitute for training. Dive within your training limits.