The Scubapro Pilot reg known to fail in a no air condition.
Show me the data on that. The design still has a downstream bias, so i suspect you'd find that any fault is not in the engineering but rather in the maintanence and adjustment of a Pilot. The Pilot is very difficult to adjust and is easy to improperly assemble as it has lots of very small parts that have to be properly oriented for it to work properly.
But to be fair, with a little thought you can improperly assemble most second stages in a manner where it will fail to deliver gas. Excessive lever play and improper engagement of the poppet are just two methods that will cause a second stage to fail closed.
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The CO2 detonator and free ascent training issues annoy me.
First, when I got certified to dive in 1985 (as opposed to "learned to dive" which occurred earlier) we all had CO2 inflators. Nobody died.
Second, we all practiced free bouyant ascents from 30'-40' of water as well as emergency swimming ascents. Again, no body died.
Third, being young, somewhat curious, and recognizing that a 32 gram CO2 cartridge was not going to produce a great deal of lift at even moderate depths, I actually tried it - first at about 60 feet and then at about 20 ft. Both were anti-climatic as at depth the lift is indeed fairly minimal and at shallow depths, the gas is easily dumped provided you have a suitably large OPV/dump valve. I concluded that even if activated accidentally, I was not going to end up imitating a sub launched ICBM.
In contrast once you drop a weight belt, especially in cold water where the belt is heavy, you are on your way to the surface, as the extra lift can't just be dumped.
In that regard a CO2 cartridge made a great deal of sense for emergency lift at the bottom (such as in an OOA event - perhaps due to an inadvertant activation of your J-Valve - where neither power inflation or oral inflation were valid options. Then, as now, dropping weights really only made sense as a means to get immediate positive buoyancy at the surface. But it seems the training agencies have gotten it all screwed up and are anti-CO2 inflator but pro "dump weights on the bottom".
With a flawed/poorly thought out protocols like that, and an absence of training in buoyant ascents, it's no surprise that there are a high number of accidents where a too rapid ascent is a causative factor. But it borders on criminal negligence when training agencies start defending their flawed protocols (drop weights at the bottom, no buoyant ascent training) by citing accident data to try to justify not changing their training protocols (i.e. buoyant ascent training would be dangerous as X number of divers are harmed during rapid ascents) when it is highly likely that their protocols are a significant contributor to both the rapid ascents and the injury to divers during those ascents.
