All depends on how many competitors and what frequencies are being used. I've seen anywhere from 2 to 14 planes in the air at once. The norm seems to be around 6 or 7 at once.

Best bet is to go to a Combat event and see what goes on there. Check the RCCA's Contest Calendar (linked to their homepage) for an event near you. There is also a Sport Combat event calendar at http://www.sportcombat.rcplanet.com/ and a New England combat calendar at http://www.demonrc.rcplanet.com

D