The air traffic controller who the Federal Aviation Administration says slept for five hours while seven planes landed at a Knoxville, Tenn., airport made a bed out of couch cushions and took a blanket into the control tower so he could nap comfortably, a federal official said Thursday.

Another federal employee, alarmed by the silence, several times entered the room where the napper was the sole controller on the overnight shift and shook him awake, the official said.

Each time the controller was awakened, he promised he would stay alert and resume his duties. But he would return to his makeshift bed and resume sleeping when the colleague departed, the official said.

The official spoke on the condition of anonymity because the official was not authorized to provide details on the Feb. 19 incident.

The FAA is moving to fire the controller. The National Transportation Safety Board was evaluating the incident but had not determined whether a formal investigation is necessary.

An audio recording of radio traffic between pilots and the radar controller indicated that more than once the controller responded, his voice difficult to understand, only to fall silent again within a few minutes when pilots tried to make contact.

At one point shortly before 2 a.m., he returned to the airwaves after an absence, gave mumbled instructions to a departing aircraft for six seconds and then fell silent again as other pilots asked for guidance.

The federal official said there were three people in the McGhee Tyson Airport control building at the time of the incident — a tower controller handling planes as they landed and took off, another federal employee and the napping radar controller. Radar controllers turn pilots toward their final landing approach while tower controllers guide them to the tarmac and boarding gates.

Each of the three was working in a different office when pilots began telling the tower controller they were getting no response from the radar controller. Unable to get a response by phone or over a direct voice system, the tower controller sent the other person in the building to the radar room, which is on a lower floor.

She found the radar controller sleeping beneath the blanket on the bed of cushions, the official said. She shook him awake and elicited a promise that he was returning to his post but returned more than once to find him sleeping again.

The incident came to light Wednesday in testimony by FAA Administrator Randy Babbitt before a House transportation subcommittee.

“This was a willful violation,” Babbitt said.

The incident occurred six weeks before a similar occurrence at Reagan National Airport. At Reagan, a controller supervisor working alone in the tower admitted to dozing while two passenger planes landed on their own.

Babbitt suspended the controller supervisor at National, and the NTSB was investigating the incident.

Not all airports served by commercial aircraft are staffed with controllers 24 hours a day. Experienced pilots regularly land at “uncontrolled” airports.

When an airport is uncontrolled, 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. With no guidance from the tower, there is a risk of collision because pilots might be unaware of equipment or airplanes on the tarmac, and ground crews might not be aware of approaching planes.

The recent events involving controllers sleeping on the job and a near-collision in January involving an American Airlines jumbo jet carrying 259 people and a pair of 200-ton military cargo jets over New York have increased concern about air safety.

Recorded errors by air traffic controllers increased last year by 51 percent nationwide.