Chicago - O'Hare International Airport, one of the busiest airports in the world, may be too busy for air traffic controllers to handle.
There were two incidents last year where they accidentally put two planes on a collision course. A tragedy was averted because the pilots were able to take evasive action in time.
A professor at DePaul University says the problem is O'Hare is an older airport with crossing patterns, creating major traffic issues in the air.
The FAA says there is now a warning signal that goes off in the control tower and the controllers sit right next to each other.