About a week and a half ago, the Federal Aviation Administration closed the air space over Raleigh-Durham International Airport and several other corridors above North Carolina. For about 28 minutes on the afternoon of June 19, all flights were halted over much of the eastern half of the state.

Skies over the region were cloudy, but there was little wind and no hint of rain, and visibility was good. No emergency was reported; no special VIP aircraft was coming through; no threat had been registered.

The reason for the shutdown, it turned out, was earthbound. The lone air traffic controller on duty for the area had been working two people's jobs for more than eight hours, and he or she finally had to go to the bathroom and get something to eat, the air traffic controllers' union claimed. It said takeoffs from Raleigh-Durham were delayed, while flights already in the air had to be redirected.

Tammy Jones, a spokeswoman for the Federal Aviation Administration, confirmed the shutdown but said no flights were delayed and no planes were placed in any danger. Four controllers at the Washington Air Route Traffic Control Center in Leesburg, Va., the radar facility that handles flights over North Carolina and four other states, had been unable to come in, probably because of illness, and for a brief period, she said, no substitute was on hand. A second controller was quickly called in, she said.

Federal aviation records indicate - and the controllers union agrees - that staffing-related shutdowns like the one at Washington Center are extremely rare. But Patrick Forrey, president of the National Air Traffic Controllers Association, maintained that the so-called ATC-0 incident over North Carolina was symptomatic of a larger staffing crisis at the FAA.

NATCA is locked in a contract dispute with the FAA, which imposed its own work rules and froze controllers' salaries in 2006, so it has an interest in criticizing the agency's management. But federal records indicate it has a good case.