I am so sorry to hear about your family's loss. Please know that we do not know how you and your family feel exactly, but we certainly do care and will be keeping your family in our thoughts and prayers.
I am fairly new to diving with around 50 dives, so this is sooo much that I do not yet know. Here is a little of what I know from my own limited diving experience. Let's say and Aluminum 80 cubic foot tank will last me about 2 hours breathing on the surface. If I go down that same AL 80 will last me about 60 minutes at 33 feet or 1 atmosphere. If I go down to 66 feet or 2 atmospheres, it lasts me somewhere around 30 minutes. The deeper I go, the less time I personally have on a tank. My mood and how I feel physically also affect how long a tank will last for me.
Once I became upset on a dive and it only took me 15 minutes to drain a tank. My breathing became very rapid and my heart was racing. I kept telling myself to calm down, but had a hard time doing just that. 5 minutes into the dive I had a problem and had to surface. Did a slow swim back up and incline and when I got out after only 15 minutes in the water, I was below 500psi. Had I waited even another minute or two, I most likely would have been out of air. The guys I was diving with still had close to 2500 psi out of the original 3000 psi in there tanks when we made it back to the surface.
500psi means I still have 500 pounds of persure in the tank. You are supposed to always plan on getting out of the water with a good bit air in your tank so that if there is an emergency you will have some air to spare to get you out of trouble. You are not supposed to plan on using all the air in your tank.
My explanation of how gas/tank air works under pressure on how your physical and emotional well being play into how long a tank will last is quite elementary. There are thousands more on this board who know much more than I do. Any specific questions that you might have, folks will go more than out of their way to answer if such answer are able to be found, especially to the family. As I said, I am new to diving and certainly open to correction from the more seasoned among us.
Some questions that you might want to ask if you can get the information are:
What was his size of tank? Had he used this tank on another dive?
How many dives had he done that day, depth, time?
What were the conditions, visibility current, temperature waves and so forth?
Did he have a dive computer? The dive computer records depth, dive time, temp, average depth, and maximum depth. Many computers also record what is happening during the dive to show what was going on 30 seconds, 60, 90 and so forth. If his computer was air integrated, it will tell how and at what rate he consumed the air.
The above questions may or may not lead you to a better understanding what happend. It is hard to know until you ask the questions and see if the answers lead anywhere.
If you have some questions that you want to ask, but don't want to post publicity because you feel they are too sensitive, send a private message to one of the moderators on this board and I am sure they would be glad to talk with you off board or point you to someone who might be able to answer a sensitive question.
We will try to be respectful knowing that this diver's family is reading the thread. Sometimes we try to speculate what might have happened and who's fault it is not out of disrespect, but to try to figure out what might have gone wrong since we don't know all the facts, but we do know something went terribly terribly wrong on this dive. We try to speculate on what might have happened and talk about it on the surface while we have lots of air to breathe, so that if we are in a similar situation underwater and must react immediately we might pull from the lessons learned on this board and perhaps might emerge out of a very dire situation ourselves. If we could figure out what went wrong and share that with your Uncle before this fateful dive, I am sure he would have found it very useful to know what he was facing and perhaps could have recovered from the problem. We are not able to go back in time and do that, if we could do that we certainly would. We are able to discuss it so that future divers might learn.
With deepest regards and respect to your family,
Leah
