US air traffic controllers should be prohibited from providing supervisory oversight while performing operational air traffic duties, the National Transportation Safety Board is recommending.
The NTSB submission to the Federal Aviation Administration is not directly related to an incident in which a Washington National airport tower controller admitted falling asleep while working alone on the midnight shift, his fourth such consecutive shift.
But the net effect of the recommendation could address the problem by requiring at least two controllers to be on duty.
Early on the morning of 23 March, several aircraft were attempting to land at National but could not contact the tower after receiving a hand-off from terminal radar approach controllers. Two aircraft landed at the airport using "uncontrolled airport" procedures before the controller came back on line.
The NTSB lists several examples of recent incidents that occurred when individual controllers were attempting to perform both supervisory and air traffic control duties, leading to errors.
One was at Washington Dulles in September 2007, when a controller-in-charge was also manning all positions in the tower while a second controller was on break - in which time a Bombardier Learjet 35 was cleared to take off on a closed, unlit runway that had only just been vacated by a work crew.
While regulations allow controllers to perform both functions "on a limited basis such as during periods of low activity" the NTSB says it is "unrealistic to expect an ATC team or a lone controller to consistently predict periods of low activity in an ATC environment".
In response to the Washington National incident, FAA administrator Randy Babbitt says the FAA is "instituting an interim plan" to ensure the situation does not happen again while the agency reviews "overnight staffing at selected airports around the country".
The interim plan requires terminal radar approach controllers to contact towers before handing off an incoming aircraft "to confirm that there is a controller prepared to handle the incoming flight".
Babbit says: "In addition, I have reminded all air traffic controllers that proper procedures dictate that they must offer pilots the option to divert to another airport if they do not make contact with the control tower." He adds that he has ordered a nationwide review to confirm back-up procedures and equipment are in place.