[laminar]

Thanks for sharing your experience and ideas, Sebastien.

Thanks Frank for your excellent comments.

A couple of questions, though, Sebastien:

1. What was your progression to 72m like? What dives preceeded it in terms of depth and difficulty? Did you jump 5-10 metres or was it incremental? How long you've been diving to these depths in this particular session?

2. Barotrauma can happen at any depth (I believe) given specific conditions. So an increase from 60m-70m is fair game for it because there are so many variables.

3. Diving below RV is not "squeeze" as Frank has pointed out. I dive below RV most of the time with the exhale/FRC method. I believe that this approach when done "properly/cautiously" (not referring to any standard or rule here, just my own judgement), squeeze risk is minimized.

4. Packing: Interestingly, it seems that studies are being considered to see how much regular packing practice increases RV (see PFI's Dr. Ralph Potkin...others too are looking into this, I believe). So by saying that packing is the only way you can get to 70m, it may also be the cause of increased RV and thus make it more likely for you to get squeezed, especially given the pressure effect of packing that fpernett descibed so well and I have theorized about in laymans terms on other threads. Ideally, your RV would be as small as possible to begin with and the dive response would activate quickly and be strong enough to protect your lungs. Harder to do with packing, I think. Much easier with FRC/exhale style diving.

5. A proper mouthfill will likely get you deeper than 72m (depending on your physiology). Are you using a mouthfill from a depth shallower than 30m for all your remaining equalizations or are you drawing air from your diaphragm for repeated frenzels?

It's frustrating to think that you're being careful and have a "squeeze" incident. That's why I've cut back progressions and line diving considerably and only venture into it with a commitment to a very slow progression, while recognizing that it's not failsafe. FRC diving has also eliminated squeeze incidents when I've been careful, also you can easily overdo it, too.

Pete