"I wonder why he didn't land," George said.
"He was checking to see if the landing strip was plowed," the man answered.
As they made a second approach, George glanced out the window and said, "It looks plowed to me."
"No," said the other passenger. "It hasn't been cleared for some time."
"How can you tell?" George asked.
"Because," the man replied, "I'm the guy who drives the plow."