A 20-year FAA air traffic control supervisor working in the tower at Washington National airport told the US National Transportation Safety Board (NTSB) investigators that he fell asleep "for a period of time while on duty" early on the morning of 23 March.
During that time, two passenger flights arrived at the airport and could not contact the tower, forcing one aircraft to perform a missed approach. American Airlines flight 1012, a Boeing 737-800 inbound to National from Miami, circled back to the airport while talking to approach controllers in a nearby facility in Virginia and landed 15min later, handling the landing "as an arrival to an uncontrolled airport", says the NTSB.
Another inbound flight, a United Airlines Airbus A320 from Chicago, also landed without any contact with the tower.
Investigators say the controller, who FAA administrator Randy Babbitt has suspended from "all operational duties", was working his fourth consecutive overnight shift (2200-0600), raising the suspicion that fatigue may have been a factor.