The air traffic controller who allegedly slept for most of five hours while on duty in Tennessee is on probation for an incident last year when police records say he dumped a drink on his girlfriend’s head and then pursued her to a local Waffle House, where witnesses said he brandished a handgun.

The Federal Aviation Administration suspended Jonathan Keith Poindexter, 27, and is taking steps to fire him after he allegedly was found sleeping Feb. 19 on a makeshift bed in the radar room of the Knoxville airport while working alone on the overnight shift.

In February 2010, Poindexter was removed from air traffic control duty and placed in an administrative post after his arrest for allegedly waving a gun during the dispute in Alcoa, a town adjacent to Knoxville’s McGhee Tyson Airport.

An FAA spokeswoman said Monday that Poindexter underwent a complete medical examination before being reinstated March 19, 2010. Poindexter had not been on duty the day of his arrest, and the conduct which led to it was not related to his job, the spokeswoman said.

Efforts to reach Poindexter were unsuccessful.

An Alcoa police report said Poindexter argued with his live-in girlfriend at the Naterz Sports Grill bar “because she was talking to another male at the bar, and [he] poured a drink on her.”

Poindexter stormed out, the police report said, and the girlfriend got a ride from the other man to a Waffle House next to the airport.

The man told police that “seconds after they arrived, Poindexter pulled up and began to run up on him with a gun in his hand. [The man] stated that he did not want any problems, so he got into his car and left. . . . Poindexter followed him into the parking lot of the Royal Extended Stay Motel. There Poindexter jumped out of the van with a handgun and began waving it in his direction, telling him, ‘You better stay away from my girlfriend, or I will bust one on you,’ ” the police report said.

After the man left, police said Poindexter got his girlfriend, “who appeared to be very intoxicated,” from the Waffle House and drove off. He later ordered her out of the van, and police found her crying near Airbase Road, the police report said.

When police caught up with Poindexter, they said they found a loaded Glock .40-caliber pistol in the van. He was charged with possession of a handgun while intoxicated and aggravated domestic assault.

The assault charge was dropped in Blount County General Sessions Court last year. Court records show that Poindexter pleaded guilty to weapons possession and was placed on supervised probation under a Tennessee practice called diversion that will allow him to seek to have his record expunged on June 16.

In the incident this year, the FAA said Poindexter was the lone controller working in the radar room in the Knoxville tower the night of Feb. 19. Another controller was working in the tower in the floor above him.

It’s the job of the radar controller to guide airplanes to and from cruising altitude while the tower controller handles takeoffs and landings. On the night that Poindexter allegedly opted to nap, the controller in the tower was still undergoing on-the-job training, said an FAA official who asked not to be named because he is not authorized to speak for the agency.

When the radar room went silent, pilots turned to the tower controller to provide the direction the radar controller normal dispenses. More than once during the five-hour period, the groggy voice of the radar controller returns to the radio for several seconds, only to fall silent again, taped recordings show.

Seven planes took off or landed during that period.

The National Air Traffic Controllers Association has been critical of the FAA’s practice of staffing some air traffic control facilities with a single controller when traffic is light during the overnight shift. Attention was called to the issue by a March 23 incident at Reagan National Airport, where a lone tower controller on the overnight shift dozed off while two passenger planes landed on their own.

Research Director Madonna Lebling contributed to this report.