A top official with the Federal Aviation Administration resigned Thursday amid the administration's embarrassment over sleeping air traffic controllers.
Hank Krakowski was the head of the agency's Air Traffic Organization, which is responsible for overseeing more than 9 million departures and arrivals at more than 400 airports every year.
"Over the last few weeks, we have seen examples of unprofessional conduct on the part of a few individuals that have rightly caused the traveling public to question our ability to ensure their safety," FAA Administrator Randy Babbitt said. "This conduct must stop immediately."
The latest incident happened Wednesday in Reno, Nev., when an emergency medical plane carrying a patient circled the airport waiting for clearance, but eventually had to land at its own risk when the pilot couldn't get a response from the tower.
The patient survived, but it was later revealed that the air traffic controller was asleep on the job.
The FAA is promising to put two people in every tower. An investigation has also been launched to analyze how well controllers are doing their jobs.
"I will make the guarantee tonight that there's two controllers in these control towers and that it will be safe to fly in and out of these airports," Transportation Secretary Ray LaHood.
John Mica, head of the House Transportation Committee, criticized the plan.
"Only in the federal government would you double up on workers...that aren't doing their job," he said.