The sole air-traffic controller responsible for directing planes to four small area airports and aircraft within 20 miles of Charleston International Airport fell asleep on the job early on the morning of Sept. 13, according to the Federal Aviation Administration.

The unidentified sleeping worker was discovered in the control tower at Charleston International around 6 a.m. by another controller who was getting ready to start the next work shift, according to FAA spokeswoman Kathleen Bergen.

Bergen said air traffic is typically light at that hour and no flights were affected.

However, Air Force jets often deploy from Charleston International early in the morning, and five commercial flights were scheduled to take off that day by 6:30 a.m., including a 5:50 a.m. U.S. Airways departure to Charlotte.

"We believe the controller just dozed off for just a few minutes," Bergen said. "We're looking into this as an isolated circumstance."

The FAA is still investigating the incident. The controller who fell asleep immediately sought medical attention but has since been cleared by FAA-certified doctors to return to work.

Bergen declined to comment on the controller's health, citing federal privacy rules. She also declined to say if the person was penalized.

The worker was alone in a dim, windowless room equipped with radar screens that track planes flying below 10,000 feet for 20 miles in all directions of Charleston International. The controller also was responsible for aircraft flying in and out of four smaller airports in Moncks Corner, Summerville, Mount Pleasant and on Johns Island.

The only other controller on duty at the time was in a different room at the top of the tower, directing planes on the ground and flights that had just taken off or were about to land at Charleston International. An air-traffic control facility near Jacksonville, Fla., controls all Charleston-area plane traffic over 10,000 feet.

The ill-timed nap happened as criticism of FAA work rules and staffing policies have risen to a clamor.

The federal air-traffic control system drew scrutiny just weeks before the Charleston incident. On Aug. 28, a Comair jet in the dark of morning crashed on takeoff in Lexington, Ky., killing 49 people.

The sole controller on duty at the time of the accident had slept only two hours since his previous shift and failed to warn the pilots they had turned onto a runway that was too short.

The National Air Traffic Controllers Association, a union, said most airport towers are understaffed.

There are 14,200 FAA air-traffic controllers in the United States, about 1,000 fewer than there were three years ago. Doug Church, a spokesman with the association, said six-day workweeks and mandatory overtime are becoming the norm at many airports.

"This is a tired work force, no doubt about it," he said. "There are fewer controllers handling more traffic than ever before."

After the Lexington crash, the FAA started reinforcing an old rule requiring that at least two controllers are on duty at all times in airports that handle commercial traffic. The FAA also threatened to suspend for up to 10 days controllers who nap during breaks.

The 23 FAA controllers who work at Charleston International, the state's busiest airport, handle about 490 takeoffs and landings a day.

At peak travel times, two controllers direct traffic from the top of the tower, while three others and a supervisor handle traffic from the radar room where the controller dozed off. Between the hours of 11 p.m. and 6 a.m., there are usually only two controllers on duty, working in separate rooms.

Officials at the Charleston County Aviation Authority and the adjacent Charleston Air Force Base declined to comment, saying that had no control over air-traffic control staff or policies.

The FAA does not keep statistics on how often its controllers fall asleep on the job and it is not required to report it when they do. The most recent such incident on record occurred in 1991 when an airline with about 100 passengers circled southern Spain for 40 minutes, while a controller snoozed thousands of feet below.

Tim Sieber, an aviation consultant with the Boyd Group in Colorado, said air-traffic controllers are the "most overworked" employees in the airline industry.

"I suspect that this probably happens more often than we think," Sieber said.

Reach Kyle Stock at 937-5763 or kstock@postandcourier.com.