[This post has been updated]

The Federal Aviation Agency is moving to fire an air traffic controller who decided to nap on the job while working the midnight shift in the radar room at a Tennessee airport in February.

Unlike a controller supervisor at Reagan National Airport who told officials he inadvertently dozed off while working the overnight shift in the tower last month, FAA administrator Randy Babbitt said the controller at Knoxville’s airport intentionally napped while seven planes landed over a five-hour period.

The Feb. 19 incident came to light Wednesday in Babbitt’s testimony before a House transportation subcommittee. He said he learned of it following the March 23 incident at National.

Landing procedures at Knoxville differ from those at National.

At National planes are turned toward their final landing approach by radar controllers based in a Warrenton facility that serves the entire region. Those controllers hand off the planes to the National tower for guidance to the tarmac and boarding gate.

At Knoxville’s McGhee Tyson Airport both the radar controller and the tower controller work on different floors of the same facility.

When the radar controller opted to nap, the tower controller stepped in to assume his duties and guide the planes to the runway.

“The FAA will not tolerate this type of unprofessional and inappropriate behavior,” the FAA said in a statement indicating the napping Knoxville controller would be fired. “The agency is committed to ensuring the safety of the traveling public and is conducting a nationwide review of the air traffic control system, including overnight staffing at selected airports around the country.”

Babbitt suspended the National controller after two planes carrying a total of 165 passengers landed on their own while he slept. After learning of the incident, U.S. Transportation Secretary Ray LaHood ordered that two controllers be regularly assigned to the overnight shift at National. Federal officials are still investigating the incident at National.

The National Air Traffic Controllers Association, which voiced concern over single-staffing of overnight shifts when the National incident came to light, reiterated that position on learning of the Knoxville event.

“Once again, we’re talking about the midnight shift,” said union spokesman Doug Church. “We continue to be concerned with the issue of safe staffing on the midnight shifts and are working collaboratively with the FAA to determine appropriate staffing levels at all facilities nationwide on all shifts.”

Not all of the nation’s airports served by commercial aircraft are staffed with controllers 24 hours a day. Experienced pilots land at what are called “uncontrolled” airports with some regularity.

There is a risk posed by a critical difference between an uncontrolled airport and one where the tower or radar controller falls asleep or becomes ill on the job. When an airport is uncontrolled, the incoming and departing pilots are on the same radio frequency as the ground crews who conduct runway and aircraft maintenance through the night.

But when controllers are on duty, ground crews and pilots work on different radio frequencies, each getting guidance from the tower controller. When that tower controller falls silent, there is a risk of collision because pilots may be unaware of equipment or airplanes on the tarmac, and ground crews may not be alerted of approaching planes.