Interesting query by Quero.
http://www.scubaboard.com/forums/aqua-lung/423981-zuma-trim-weight-pockets.html
This hints at the fact she was used to diving overweighted while being sensitive to her trim and balance.
The analysis in this thread paints a clearish picture as to the likely chain of events, but leaves some blanks which may never be filled in.
One of those blanks looks to be that she had a plan(her own plan not communicated to the rest of the team, but neverless, a plan). Evidence shows that she was well aware of being overweighted, and experienced and comfortable being overweighted.
Has there actually been an autopsy released with cause of death?
Was the dive computer AI?
Many questions will be answered when that information becomes available.
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Lessons can and will be learned, and indeed it has stimulated introspection. In my personal diving, and as an underwater photographer, it has begged me to ask if I can improve my team skills. Can I be a better buddy?
Professionally, I've extensively discussed this situation with the candidates in my current DM class.
How could the group have done better? What can we learn and apply to our diving?
Some of our discussion:
1. Communication, predive planning, post dive debriefing.
A.) Quero's straying on previous dives had frustrated the group. A plan to alleviate those frustrations should have been implemented. If no consensus could be reached, they could have cancelled the next dive.
B.) Define and agree on expectations of teammates. Buddy contact and obligations vary among individuals.
2. Mid-Dive (assumed) buddy switch.
A.) Divers 1&2 started together. Divers 3&4 started together. If diver 2 decides to go with diver 4 part of the way through the dive, all parties should be aware and in agreement. Assuming that diver 2 is proceeding with diver 4, without confirmation, just relies on luck.
3. Define the goal for the dive and who will lead.
A.) Was the goal to photograph Weedy Sea Dragons? Were they all there to support Quero's quest to do that. Was she (in her mind) by default leading the group in her quest?
4. Regardless of level of frustration, finish the dive together.
or thumb it
or insist on immediate behavior change.
5. Who hasn't gotten a little looser at the end of an easy shore dive, in shallow water?
....Especially if everyone in the group is very experienced....
Less diligent buddy contact, taking back gas below reserve, assumption that everyone can easily finish the dive and exit on their own, are dangerous practices.
The likelihood of OOG, DCI, dehydration, hypothermia, hypoglycemia, and exhaustion, are greater at the end of a dive.