Analysis of Freediving Tragedy Beginning to Take Form
Posted By Paul Kotik on 22 October 2002
Analysis of the forensic data from Audrey Mestre's fatal accident has continued without pause throughout the nine days and nights that have passed since that dreadful day. The lead independent investigator is Kim McCoy of Ocean Sensors (kmccoy@oceansensors.com) a physical oceanographer with over 20 years' experience in marine instrumentation, who has certified many prior world record attempts and has completed the deepest biomedical experiments to date on divers. Kim McCoy participated in this world record attempt as an individual, at Audrey's request, to provide an independent authentication of her record depth.
McCoy, who provided the data recorder Audrey wore during the dive, was on the dive boat when the accident occurred. He has had full access to video and still imagery, examined the sled and other gear repeatedly after the accident. He has interviewed everyone involved with the dive, and preparations for the dive, both at the scene and again in the days afterward. He has spoken at length with Pascal Barnabe, the bottom trimix diver, several times since Pascal returned to France.
"My duty is that of reconciling the available data by constructing the highest-probability account of what happened", McCoy explained to me today. "I want to account for as much of the data as I can, making as few untestable assumptions as I can." Kim reminded me that Einstein once recommended that theories should be kept as simple as possible -- but no simpler.
The Ocean Sensors device is the analog of a commercial airliner's flight data recorder, the so-called 'black box' upon which investigations of aviation disasters rely. The device records depth measurements on a time line, at resolutions sufficient, for example, to allow McCoy to recognize in the graph when a sled diver has tilted her head back during ascent to look up at the surface.
When I talked to McCoy on Saturday, one week after the accident, he outlined the analytical process he had been carrying out since the investigation began, back in the Dominican Republic.
"First, I draw up outlines of every plausible scenario I can think of, setting aside, for the moment, any objections which might be made. I cast as broad a net as I can. For example, I would outline a scenario in which a whale shark parked itself under the sled as it descended. Anything plausible is on the table. Next, I identify the component assumptions in each scenario, the things that had to have happened in order for that scenario to have unfolded. Then, I characterize the logical relationships between these component assumptions."
Some assumptions are mutually exclusive, and cannot both be true. Others have conditional relationships : if one is true, so must be the other, or, one can only be true if the other is, too.
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