Here is some recent information provided by Dr. Richard Vann at DAN concerning their on-going studies about flying and returning to altitude after diving:
"After a 60 min dive to 40 fsw with dry resting divers, we were DCS-free in 23 exposures at 8000 ft simulated altitude with a 9 hr preflight surface interval. We had 5 DCS incidents in 41 exposures with an 8 hr surface interval."
DAN promulgates and recommends the following:
The final upshot of the debate is a DAN revised guideline which states:
a. A minimum surface interval of 12 hours is required before ascent in a commercial aircraft (8000 foot (2438 m.) cabin).
b. Wait an extended surface interval beyond twelve hours after daily, multiple dives for several days or dives that require decompression stops
c. The greater the diving the longer the duration recommended before diving.
The above is for sports diving and should not apply to commercial diving or nitrox diving. Because of the complex nature of DCS and because decompression schedules are based on unverifiable assumptions, there can never be a fixed flying after diving rule that can guarantee prevention of bends completely.
UHMS recommendations are located in a table at
http://www.scuba-doc.com/flyngaft.htm