I guess that is the part that just seems wrong. Taking a diver that is not certified for deco and has no training for deco (i.e. they're not doing that as part of a DP class) on a dive where they incur deco seems like it would be a standards violation with ANY agency. Weird.
In that scenario, I assume the student does their deco on back gas? And how do they know their ascent profile? Are they just expected to fly their computer? They're screwed if their computer dies?
It depends on the instructor, but in my full cave class deco with O2 was the norm. At a minimum, the cave relevant skills that must be taught are proper placement of the bottle on the line in the cavern and switching to O2 on exit.
Gas switch protocols need to be covered, but with a limited number of dives to cover the requisite Cave skills as well as decompressions skills, students don't have the time or the bandwidth to focus on meaningful levels of decompression training - not to the same extent they would have in an AN/DP class where it is the primary focus of the class.
The same thing applies to the nuances of high percentage O2 use. That's made even more critical when you look at the use of nitrox on long cave dives, where you'll also be using high percentage O2 decompression mixes - 100% O2 is the norm in N FL, but it's not always the optimum choice, and it's vital that things like oxygen toxicity and back gas breaks are covered.
If you polled a number of cave divers Cave certified through agencies that don't offer AN/DP and who never had AN/DP training, I suspect most of them were not exposed to the planning implications of a long dive with a high PP02 bottom mix, and extended deco on O2, particularly on a repetitive deco dive.
Part of the reason for omitting that in training may be an artifact of the Cave training standards being applicable to places other than just N FL. In N FL caves are deep and deco on a long dive at the full cave level is the norm. However in other places, the caves used for training may be shallower and deco may never be encountered. I suspect that's why deco isn't addressed in detail in the Cave course requirements.
But that doesn't eliminate the need for proper deco theory to be taught for divers who are learning and diving in those environments, along with lost deco gas contingency planning, and maintaining enough reserve to enable you to do the much longer back gas deco that may be required.
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Trimix poses the same challenge to a Cave diver as the planning and techniques you'd use offshore don't fully translate to trimix planning or diving in caves. But fortunately for divers at the full cave level, so one seems to get upset when a Cave instructor takes a Cave certified student below 130' on a training dive, because the END should still not exceed 130'.
But given that all the important bottle and gas switching skills are learned in AN/DP and only reviewed and refined in Trimix, it's important for the trimix student to have that AN/DP level of training somewhere, and it's preferable for a cave diver if they can get in a cave.
