WASHINGTON, D.C. – The National Transportation Safety Board today opened an investigation into an air traffic control service interruption incident that occurred early Wednesday morning at Washington Ronald Reagan National Airport (DCA) in Arlington, Virginia.

On March 23, 2011, between approximately 12:04 am and 12:28 am EDT, an air traffic control service interruption occurred when two air carrier aircraft and controllers at the Federal Aviation Administration’s Potomac Terminal Radar Approach Control were unable to establish contact with the supervisory controller working alone in the DCA control tower.

The last radio transmission made by the tower controller before the service interruption occurred at 11:55 pm EDT on March 22. At 12:04 am EDT on March 23, American Airlines flight 1012, operating as a scheduled 14 Code of Federal Regulations part 121 flight between Dallas-Fort Worth and DCA, was instructed to contact Washington tower by approach controllers at TRACON.

Following numerous attempts to contact the DCA tower, the flight crew executed a missed approach. The crew reported to TRACON their inability to make contact with the DCA tower; TRACON then vectored the aircraft back to the airport for another approach.

The approach controller and the TRACON supervisor on duty made several attempts to contact the tower controller via telephone, but were unable to establish contact. The TRACON approach controller advised the crew of American flight 1012 that the tower was apparently unattended, and that the flight would be handled as an arrival to an uncontrolled airport.

The flight was again cleared for approach, and instructed to switch to the tower frequency. At 12:12 am, the crew returned to the tower frequency, still unable to make contact with the tower, made position reports while inbound, and landed on runway 1.

United Airlines flight 628T, operating as a scheduled 14 CFR 121 passenger flight from Chicago-O’Hare International Airport to DCA, was advised of the service interruption by the TRACON approach controller and subsequently transferred to the tower frequency at 12:22 am.

The United flight, unable to make contact with the tower, made position reports on the tower frequency while inbound, and landed at 12:26 am. At 12:28 am, American flight 1012, on the ground at DCA, established contact with the tower controller, and normal services were resumed.

The controller in the tower at the time of the incident, along with other FAA officials at DCA, were interviewed by the NTSB today. The controller, who had 20 years’ experience, 17 of those at DCA, indicated that he had fallen asleep for a period of time while on duty. He had been working his fourth consecutive overnight shift (10 pm – 6 am). Human fatigue issues are one of the areas being investigated.