Now the Federal Aviation Administration is investigating, and local authorities are considering charges.
"We're all pretty dumbfounded," said Lincolnshire Police Chief Randy Melvin. "I don't have any idea what the guy was thinking. He was going to park his plane across the street like nobody would notice."
Kadera, a 65-year-old electrical engineer, flew his 14-year-old son, Isaac, in a four-seat 1949 Piper Clipper from their Lake Villa home to the golf course in Lincolnshire across a highway from the tennis club. They were on their way to the tennis club when authorities stopped them.
The plane had had to circle twice before landing Saturday afternoon, and witnesses called police, fearing there had been a crash.
Kadera, a Navy veteran with about 40 years of flying experience, wasn't allowed to fly the plane home, and it had to be towed.
He said he thought flying his son would be "a convenient way to get him down there and get him to his tennis on time."
And next time, he said, he'll drive.