by Gabe BullardPilots are practicing now for Saturday's Thunder Over Louisville air show, and while clear skies are predicted, many fliers will face unique challenges.Thunder is held in a smaller space than many air shows, and stunt pilot Michael Wiskus says he's taking precautions to keep his biplane between the bridges and above the river."Normally at air shows, you're over a runway and you've got all this length and all this time and all this altitude and no end restrictions or anything like that and it's never a problem," he says. "In this case, you've got a lot of barriers around that you've got to keep an eye on and make sure you keep your distance with."This is Wiskus' second year flying in Thunder. The air show begins at 3:00 and ends at 9:30. It's followed by fireworks.