WASHINGTON – The Federal Aviation Administration on Friday replaced three high-level managers in the nation’s air traffic control system following embarrassing incidents of controllers sleeping on the job and making potentially dangerous mistakes.

In a shake-up of the system, new managers were appointed to key positions that oversee the operation of airport towers and regional radar centers that handle planes flying at high altitudes as well as approaches and departures, the agency said in a statement. A new manager was also appointed to run a regional radar center near Cleveland. The previous managers are being reassigned.

The performance of mid-level managers is also being reassessed, the FAA said. And teams of experts are examining several of the agency’s more complex facilities, including the Cleveland center and one on Long Island in New York, to ensure agency policies are being followed and professional standards upheld.

“This sends a powerful message, and it’s the right message,” said Gregory McGuirk, an associate professor of air traffic management at Embry-Riddle Aeronautical University in Daytona Beach, Fla. “It’s one way to shake up the culture.”

But Missy Cummings, an associate professor at the Massachusetts Institute of Technology, said shuffling managers doesn’t get at the root cause of many of the incidents.

The limits of human physiology necessarily mean that night shift workers in all industries, not just controllers, are going to fall asleep on the job from time to time, said Cummings, a human factors expert. Boredom is also a factor. The less activity there is to keep workers’ minds engaged in the dead of night, the more likely they are to fall asleep, she said.

Earlier this month, a controller working an overnight shift at the Cleveland center was suspended for watching a DVD movie while he was supposed to be directing air traffic. In February, a supervisor at the Long Island center complained that controllers on late night shifts routinely took naps during breaks and played electronic games when traffic was light.

On Wednesday, FAA replaced the acting manager of a regional radar facility in Warrenton, Va., that handles approaches and departures for airports in Virginia and Maryland. The action came a week after a controller at the facility allowed a plane carrying first lady Michelle Obama and Jill Biden, wife of Vice President Joe Biden, to fly less than three miles behind a much larger military cargo jet as the planes approached Andrews Air Force Base in Maryland.

FAA regulations require a separation of at least five miles when the plane in the lead is significantly larger to prevent the trailing plane from encountering dangerous wake turbulence. Controllers at Andrews also directed Obama’s plane to abandon its landing and circle the air base to give the cargo jet time to get off the runway.

Also Friday, FAA named a five-member review panel composed of internal, labor, industry and academic safety experts to evaluate the agency’s training of new controllers.

“This is just the beginning of the process to make sure we have the best possible team in place,” Transportation Secretary Ray LaHood said.

The changes are part of a comprehensive review that LaHood and FAA Administrator Randy Babbitt promised after a series of incidents that have embarrassed the agency, made controllers the butt of jokes by late night comedians, and raised public jitters about the safety of flying.

Since late March, the FAA has disclosed five incidents of controllers sleeping on the job. Three of those controllers have been fired, while two others and a manager involved in the incidents have been suspended. In one case, a plane transporting a critically ill patient had to circle Reno-Tahoe International Airport because the pilot was unable to reach the lone controller working an overnight shift in the tower. In another, two airliners landed at Reagan National airport near Washington without control tower assistance because the lone controller on duty at midnight had fallen asleep.

The controller who watched the movie in Cleveland and a manager at that center also have been suspended. So have two controllers at an airport tower in Lubbock, Texas, who were unreachable for a period of time while working an overnight shift.