When arriving early at the first "D" stop, what is the action during an air stop?

When arriving early at the first "D" stop during an air dive, the appropriate action is to begin the stop time when the travel time is completed. This means that even if a diver arrives at the designated depth for the decompression stop before the calculated travel time has elapsed, the stop time should not start running until the entire ascent and travel time have been safely completed. This practice is essential because it ensures that the diver appropriately de-compresses at the required depths for the full duration as planned, thereby minimizing the risk of decompression sickness. Timing of stops is critical in diving physiology since it helps manage inert gas elimination from tissues, ensuring a safer ascent. This approach reflects a systematic adherence to established decompression protocols.