I would like to make an observations about multi-step safety procedures in general, and I would like to start by talking about something not remotely related to scuba.
When I first became involved with scoring student writing assessments, we were given a scoring guide that was incredibly complete and complex. I immediately wondered how it was possible to use something that complex, and I soon realized that it wasn't possible. The people scoring the assessments were doing it more by personal whim than by careful design. I came up with a theory of my own: when a system is too complex to be used as intended, users will ignore it, so an overly complex system is the same as no system. As I moved on to more professional assessment systems, I saw procedures that were far simpler and much more usable.
My earliest technical diving training required us to use a very, very careful and complex system to ensure we made correct gas switches at depth. Following that procedure made it downright impossible to make a mistake. The problem was that it took forever. The initial deep stops are very short, and during a deeper gas switch, we would have to go far, far beyond the deco stop time to complete the process. Once certified and doing dives outside of instruction, I immediately noticed that divers, including my instructor, were very much skipping steps, ignoring that laborious procedure. It was the same as assessing student writing--if you don't follow the approved procedure, than you don't have an approved procedure.
Switching agencies to complete my trimix instruction, I learned a much simpler system, and my years of diving later on showed that pretty much everyone uses that simpler approach. Is it more dangerous? I guess in theory it is, but the reality is that gas switch errors are very rare. As I pointed out earlier n this thread, almost all cases of breathing an incorrect mix at depth, including what we know of this one, did not involve a faulty switch procedure.
When I first became involved with scoring student writing assessments, we were given a scoring guide that was incredibly complete and complex. I immediately wondered how it was possible to use something that complex, and I soon realized that it wasn't possible. The people scoring the assessments were doing it more by personal whim than by careful design. I came up with a theory of my own: when a system is too complex to be used as intended, users will ignore it, so an overly complex system is the same as no system. As I moved on to more professional assessment systems, I saw procedures that were far simpler and much more usable.
My earliest technical diving training required us to use a very, very careful and complex system to ensure we made correct gas switches at depth. Following that procedure made it downright impossible to make a mistake. The problem was that it took forever. The initial deep stops are very short, and during a deeper gas switch, we would have to go far, far beyond the deco stop time to complete the process. Once certified and doing dives outside of instruction, I immediately noticed that divers, including my instructor, were very much skipping steps, ignoring that laborious procedure. It was the same as assessing student writing--if you don't follow the approved procedure, than you don't have an approved procedure.
Switching agencies to complete my trimix instruction, I learned a much simpler system, and my years of diving later on showed that pretty much everyone uses that simpler approach. Is it more dangerous? I guess in theory it is, but the reality is that gas switch errors are very rare. As I pointed out earlier n this thread, almost all cases of breathing an incorrect mix at depth, including what we know of this one, did not involve a faulty switch procedure.
