What procedural step is necessary when using the RDP for dives higher than 1000 feet?

When utilizing the Recreational Dive Planner (RDP) for dives at altitudes exceeding 1000 feet, it is essential to allow a minimum of 6 hours to acclimatize to altitude before diving. This is because ascending to higher altitudes changes the atmospheric pressure and can influence how nitrogen is absorbed and released by the body. The RDP guidelines are designed to ensure divers are aware of and compensate for these changes to reduce the risk of decompression sickness.

Adhering to the recommendation of waiting at least 6 hours allows nitrogen levels in the body to stabilize, helping to maintain safe diving practices. This step is particularly crucial for divers who have recently traveled to altitudes above 1000 feet, as the changes in ambient pressure can markedly affect dive planning and execution.

In this context, the other choices do not align with the established guidelines. Diving closer to 1500 feet does not address the need for proper acclimatization; only skilled divers is not a standard criterion for altitude diving; and asserting that no special procedures are required overlooks the importance of altitude acclimatization in safe diving practices.