The air traffic controller at the center of the controversy surrounding a pair of flights that had to land at Ronald Reagan Washington National Airport early Wednesday morning without ATC clearance from DCA told NTSB investigators that he had fallen asleep, the Safety Board reported this evening. The 20-year-veteran controller, who the FAA suspended today, had been working his fourth consecutive overnight shift (10 p.m. to 6 a.m.)

According to today’s NTSB report, on March 23, between approximately 12:04 a.m. and 12:28 a.m. 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 (Tracon) could not 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 p.m. on Tuesday night. At 12:04 a.m. Monday, Tracon instructed American Airlines flight 1012, operating a scheduled passenger flight between Dallas-Fort Worth and DCA, to contact Washington tower. 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 could not establish contact. The Tracon approach controller advised the crew of Flight 1012 that the tower was apparently unattended, and that the flight would be handled as an arrival to an uncontrolled airport. 

The flight again received clearance for approach along with instructions to switch to the tower frequency. According to the NTSB report, “At 12:12 a.m., 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.”

Tracon then advised United Airlines flight 628T, operating a scheduled passenger flight from Chicago-O'Hare International Airport to DCA, of the service interruption. That crew subsequently transferred to the tower frequency at 12:22 a.m.

The United flight, unable to make contact with the tower, made position reports on the tower frequency while inbound, and landed at 12:26 a.m.

At 12:28 a.m., American flight 1012, on the ground at DCA, established contact with the tower controller and normal services resumed.

The NTSB said it will interview officials at the Tracon facility tomorrow.