I can second Thalasmania's response when you add both his threads together. First, a diver who uses properly maintained equipment and follows their dive plan and reads their gauges regularly will likely NEVER have a no air emergency. A diver who stay in close proximity to a buddy (and that is the whole poit of having a buddy) will always be able to acquire air from them. If for some unknowable reason, a true out of air emergency arises with no air available, every diver should train for that emergency. Things like exploiting any air in the bc, being reasonably able to slowly expel the last breath as you ascend, and so on, are skills that any diver can and should learn at some point in your training. As to the use of the term"criminal negligence," though, Thalasmania is incorrect. If there is a true out of air situation the diver alone is the negligent one in most cases, and in very rare occasions, it may be an equipment manufacturer or more likely the person who improperly serviced the gear, or the entity that rented out faulty gear. ( I've been an attorney doing civil and criminal trial work for over 33 years) Every diver needs to take responsibility for their skills, their equipment, and their activities.
DivemasterDennis
DivemasterDennis