But try telling them that.
Several participants in the "5K on the Runway" race made mock jet sounds and threw out their arms to pantomime an airplane. Some even ran with floppy plastic jets on their heads.
Real jets using adjacent runways screamed just hundreds of feet overhead during the race, and bright red signs along the route warned they were in an area where aircraft were moving.
The event was designed as a community outreach effort to unveil the airport's newest runway since 1971. Proceeds will support a $750,000 sculpture called "Runners" that will be installed at O'Hare.