all kinds from little home-built airplanes that they build out of steel tubing and wood to big jets. oshkosh airport becomes the busiest airport in the world for that week. there will be as many as 13,000 airplanes. >> during air venture, the population of oshkosh skyrockets as people pour into the city on highway 41. >> it's busy all day because people are going to and from the air show at all different times. >> the leff's are having an uneventful flight. >> the engine had been running smoothly. i even commented to my son on how good things were. >> 20 miles south of oshkosh over fond du lac, the engine dies. >> the engine totally quit at that point. the engine was shaking pretty violently. >> the plane loses altitude quickly. >> to be honest with you, the first thought came to my mind is this isn't good. >> bill knows there's a small airport in fond du lac.