Well, it just goes to show you all that there is no perfect method. I happen to use the 45, have been teaching the sport for almost 15 yrs and teach my students the same. So far, there hasn't been any problems. Tom has a good point that I have been trying to get across to jumpers for awhile. Having over 2100 hrs myself flying jumpers, groundspeed and time isn't that bad of a method if you really know how to count accurately and do the basic math. As I said there is no perfect solution, I feel that you should use the method that seems to work best for you and your DZ. You don't have to go to MIT to realize that you really should leave more than a couple of seconds between groups Bill. And I really have a hard time with the fact that your otter pilot was flying in a level attitude!! How much separation do you really need? Where is it most important? I kind of think it is at the opening point. Have a great day Y'all.