In 1975 when I became certified as an NACD cave instructor we used a gas management rule in high flow caves such as Little River and Devil's Eye/Ear known as half + 200. The rationale was since we were swimming against high flow on the way in and being pushed out by that same flow it was acceptable to use this gas management rule.
The way it worked was, for example if we started with 3000 psi we could penetrate until we hit 1700 psi. (3000/2)+200=1700 psi was turn pressure.
Since this was a solo dive the exact plan is unknown, however, we do know that the diver had stated previously that he intended to alter the gas management rules to extend his bottom times. The recovery divers were able to reconstruct some of the routes and jumps the victim made. The recovery team concluded that the victim made a navigational error during his exit, likely due to a siltout that caused zero, or near zero visibility.
The recovery team also concluded that the victim was eventually able to correct his navigational mistake and was able to head toward the exit after considerable time being lost in the cave.
The victim was found only a couple of hundred feet from the exit.
