The first dive profile tested was to 60 feet for 55 minutes. The results from this series of tests showed that at surface intervals up to 10 hours divers still experienced symptoms of DCS when exposed to simulated altitude conditions. However, no symptoms of DCS were seen in subjects who had a surface interval of 12 hours or longer. This could be interpreted as supporting DAN's recommendation of a surface interval longer than 12 hours for divers who make multiple dives. A Conservative View Michael Emmerman, director of the Special Operations Support Group and an independent researcher who has worked and published extensively on the subject of flying and diving, feels that the recent DAN research is significant.
Most researchers agree that chamber dives are less strenuous than open-water dives.
If one were to add an additional 50 percent to this interval, then we're back to the 24-hour recommended surface interval. Emmerman says further research is needed in this area before definite answers are known and accepted as scientifically valid, but in the interim he feels that the current recommendations are reasonable, and supported by the emerging data. According to Dr. Richard Vann, DAN's research director, there have been a total of 540 chamber dives conducted to date, with 22 suspected DCS hits. These ongoing projects aim to obtain information from over one million actual dives. However, Vann points out that even though participants are asked to record pre-flight surface intervals, the flying after diving question is not what the project has been designed to address, and is unlikely to provide any definitive answers.