Many divers are taught a shoulder drop and/or arm sweep method for recovering their regulator. Often that does not work. The idea of an emergency procedure that you can not count in is a strange one to me. I teach: Left hand goes under the tank and lifts, right hand reaches over the top to the regulator first stage, encircles the IP hose and then pulls outward and slides down the hose. Now the second stage is in your hand and you're reay to go. I've watched too many divers flail, and fail, and flail again, doing armsweep after paniced armsweep.
There have been a few accidents over the years involving divers who lost their regulator from their mouth and continued to perform arm sweep after arm sweep, without success, in an attempt to effect a recovery. In the two cases that I am most familiar with, the divers also lost concentration on buoyancy control and were last seen dropping like a stone by buddies who could not catch up with them, and abandoned the chase at significant depth. In both these cases the description was the same, “… sunk out of sight over the wall, kept doing arm sweeps.” It would appear that the technique had been so ingrained and their perception had so narrowed that that was all they could do.
This problem is especially true when it involves a change in gear that demands a change in procedure. Those two arm sweep incidents occurred with moderately experienced divers shortly after the introduction of auxiliaries, so why didn’t they just shift to their auxiliary and then go looking for their primary? Reverting to old learning under pressure is a well-understood principle. It is similarly illustrated by a story regarding a
fighter jet from the 1960s. Pilots ejected whenever anything went wrong. The engineers couldn’t find any pattern to the ejections. It didn’t matter whether the failure was a stall, a spin, hydraulics, a flame out, locked ailerons, no matter what happened, the pilot became a member of the Martin-Baker Tie Club. When the pilots’ flight histories were reviewed, it was found that all had transitioned to this aircraft from the same former aircraft. Furthermore, the cockpits of the two aircraft were almost identical. But there was a critical difference, the throttle and ejection seat handle positions had been switched. Pilots flying the new plane had no problem until something went wrong, when it did they reverted to old behavior and mistakenly ejected when they wanted to apply power.
So what do we do? I feel that a combination of training techniques is required. Divers need to have confidence in their ability to fix things on the fly within a given timeframe. We typically work with what are calling “dynamic drills” in thirty second blocks, (e.g., if you can’t solve it in 30 seconds you’re not going to solve it). Why 30 seconds? That’s rather arbitrary, but we established that guideline based on two criteria, and that‘s where the combination of things comes into play: a thirty second breath hold is not a big deal for our students, even if the problem is discovered after exhaling and while attempting to inhale; and all of the dynamic drills that we do can be accomplished in less than 30 seconds from onset to resolution, with the exception of the deep ESAs that we no longer teach.
The reach back and follow the hose has to work (if it doesn't you've much larger troubles than you thought) yet I've watched lots of divers (in real and other classes) do arm sweep after arm sweep, with each one getting faster and more spasmodic, until having reached critical mass they bolt for the surface. One of my instructors even started using an arm sweep as the hand signal for, "look out boss ... he's-a-gonna go!"