Sliney had left air traffic control a few times to practice law, most recently at the beginning of the 1990s. In late 2000 he again became a controller. “I had come back three or four times,” he says in a New York accent. He took a seat in Herndon as a rank-and-file operations guy. “I’d been out for 10 years. I said, ‘Let me be a journeyman for a while.’ I wanted to get all the equipment and tools under my belt.” In a year, he was promoted to national operations manager, the top decision maker on the floor. Sliney’s first day on that job was Tuesday, September 11.
At 8:46 a.m. he was on a routine conference call when an airplane struck the north tower of the World Trade Center. Sketchy information followed: American Airlines flight 11, out of Boston, had shut off its transponder, and a flight attendant on board had been stabbed. The military liaison at the command center suggested putting CNN up on one of the screens at the front of the room; the cable network reported that a small airplane had hit the tower.
“I said, ‘That’s no small plane’—the conflagration was huge,” Sliney recalls.
New York controllers reported that the pilots of United 175, also out of Boston, weren’t responding. That airplane’s transponder was still active. At 9:03, the airplane arrived at the tip of Manhattan.
“He made a hard left turn and dove like a manhole cover,” Sliney recalls. On their data screens, he and his staff watched the 767’s altitude plunge, and looked up in disbelief at the screen as the airliner rammed into the south tower. “It was the most horrifying sight I think any air traffic controller could ever see,” he says.
He ordered a ground stop, which keeps flights from taking off, for the entire continental United States. Nationwide, en route centers were told to report any airplane that shut off a transponder, ceased voice contact, or altered course or altitude without clearance. Sliney set up a white board at the front of the room, where his team listed suspect flights. The list included American flight 77 and United flight 93. At 9:37, flight 77 struck the Pentagon, outside Washington, D.C. Sliney ordered the first-ever unplanned grounding of all airplanes in the nation.
“I gave that order, and I had maybe 30 type-A personalities gathered around me—these people wanted to do something,” says Sliney. The controllers ordered all pilots to divert immediately to the nearest airport. “I expected to get a lot of push-back [from pilots],” says Sliney. “Well you know what? I had one specialist come back to me and say, ‘So-and-so wants to know if they can go to this airport instead of that one,’ and I said, ‘No, they have to land at the nearest,’ on the supposition that I don’t know who’s in that cockpit.”
Sliney’s team watched United 93. “It kind of meandered,” he recalls. “It didn’t seem to be heading anywhere until it started toward Washington.” At 10:03 a.m. it went down in a field near Shanksville, Pennsylvania.
By noon, about 4,000 commercial airplanes had landed. It would be two days before any commercial flights were allowed to take off, and then, only on a case-by-case basis. More than a week would pass before general aviation airplanes were allowed to fly under visual flight rules, but with restrictions on airspace.
“When [command center manager] Jack Kies had wanted me to take the job as national ops manager,” recalls Sliney, “I asked him, ‘What is the scope of my authority with regard to the national airspace?’ And he replied that it was unlimited. That figured in my mind when I decided to land everyone. I had asked him directly, and he had told me directly.