What is the prescribed rest time for a flight crew before returning to service after scuba diving?

The prescribed rest time for a flight crew before returning to service after scuba diving is indeed 12 hours. This guideline is based on the fact that when a diver ascends from underwater, nitrogen can be absorbed in the body tissues. If an individual were to fly soon after diving, the reduced pressure in the aircraft cabin could lead to the release of nitrogen, potentially resulting in decompression sickness, commonly known as "the bends."

The 12-hour period is recommended to allow sufficient time for this nitrogen to dissipate from the body, thus minimizing the risk of any medical emergencies related to residual nitrogen in the tissues. While some may think that shorter durations could be allowable, the 12-hour limit is established based on precautionary measures aimed at ensuring the safety and well-being of flight crews and passengers. This practice reflects a careful consideration of both physiological factors impacted by diving and operational safety standards.