The morning Comair Flight 5191 went down, killing 49 people there was only one air traffic controller working.
The Air Traffic Controllers Union says that's a problem and they want a federal safety board to recognize the issue.
The union petition filed with the National Transportation Safety Board saying two controllers would have presented a better chance at stopping the Comair plane from using the wrong runway. They want that included in the board's findings on the 2006 crash. The NTSB did not cite understaffing of controllers as a contributing factor.