NTSB Chairman Mark Rosenker told the Austin (Texas) American-Statesman Monday that things "could fall apart" if the control system isn't constantly improved.

"When we start adding complacency to the equation, you create an environment where mistakes can be made," he said.

Rosenker was reacting to a report by the U.S. Department of Transportation that stated controllers at the busy Dallas-Fort Worth airport had deliberately misclassified incidents in which planes nearly collided in order to downplay their seriousness.

He told the newspaper he is also worried that the risk of a disastrous collision on the ground due to runway incursions could be growing.