Aviation Week & Space Technology, December 17, 2001
Crisis at Herndon: 11 Airplanes Astray
By DAVID BOND
To understand fully why the U.S. government brought down 4,546 aircraft within 3 hr. on the morning of Sept. 11, all you need to know is this: The second of two hijacked airliners is flown into the World Trade Center at 9:03 a.m. EDT. Minutes later, the FAA's air traffic control command center in Herndon, Va., tells field facilities to advise it of any aircraft that aren't in communication or are flying unexpected routes.
The facilities report 11 such aircraft. Hijackers fly one of them into the Pentagon at 9:41.
Ten are left.
The order to empty the skies goes out 4 min. later . . .
At about 7:15 a.m. on the morning of Sept. 11, 2001, air traffic control personnel at the FAA's ATC System Command Center in Herndon, Va., began a normal daily teleconference with airline and FAA field facility representatives to develop the day's game plan for keeping U.S. aviation as close to schedule as possible.
Approaching the end of a summer with markedly better weather and system performance than the delay-riddled summer of 2000, Herndon had reason to be optimistic about Sept. 11. It started out as a very normal day, recalled Linda Schuessler, manager of tactical operations at the command center. The weather was absolutely gorgeous. The only thing that was atypical as the day began was how good everything looked.
The first suggestion of trouble came at the start of Herndon's next routine event, the daily 8:30 a.m. senior staff meeting, which reviews the previous day's operations and discusses the current day's weather forecast and game plan. During the previous half hour, four aircraft that would make Sept. 11 an infamous and historic date had taken off from Boston, Newark and Washington (see timeline).
THE NATIONAL OPERATIONS manager (NOM), in charge of supervisors and ATC specialists on the command center's operational floor, normally a key participant in the staff meeting, reported a possible hijacking in progress, and returned to the floor. Later, a supervisor interrupted the meeting to report that a flight attendant on the hijacked aircraft may have been stabbed. The meeting broke up. Returning to the floor, the meeting participants got a CNN report that a small aircraft had crashed into one of the World Trade Center towers. It was 8:46 a.m.
Herndon set up a teleconference with FAA facilities in the New York area -- the en route center, the Tracon, the regional office. The participants decided jointly to divert all air traffic that otherwise would enter the area, either to land or to overfly. They [New York area ATC personnel] would continue to work what they'd been working, but we wouldn't give them any more, Schuessler said. The decision did not affect takeoffs from the area.
Then, within a few minutes, a second aircraft crashed into the World Trade Center, Schuessler said. It was obvious that it was a commercial jet . . . [O]ne of our big screens [at the command center] was watching CNN, so we were seeing it live, like so much of the rest of the country. We expanded the telecon we were holding with the New York facilities to include our FAA headquarters office, the secretary of transportation's office and other agencies. It was expanded quite a bit.
At this point we had two crashes. We in the command center started receiving information from FAA field facilities about unusual things that were going on. We started among ourselves trying to decipher the information that was coming in . . . The NOM, three first-level supervisors and I were gathering information from around the country that the specialists were getting. Every few minutes, we would gather in the middle of the operational floor and share the information and discuss what some of our options might be, what we needed to be doing. A manager kept the telecon line open.
The kind of government-industry coordination Herndon relies on to deal with bad weather turned instead to crisis management. As usual, the Air Transport Assn. (ATA) and the National Business Aircraft Assn. were represented on the operational floor. In a fluke, so was what Herndon calls the military cell -- the Air Traffic Services Cell, created by the FAA and the Defense Dept. for use when needed to coordinate priority aircraft movement during warfare or emergencies. The Pentagon staffs it only three days per month for refresher training, but Sept. 11 happened to be one of those days.
Schuessler secured the command center, because we didn't know exactly what the situation was and what was going on. Non-Herndon, non-FAA people were asked to leave.
We were continuing to call the air traffic facilities, and at one point we asked them to advise the command center if they had any radar targets that started dropping off the radar scope, or any deviations from their route of flight, or any loss of communication. These things happen routinely, and usually the facilities handle it. But we felt that we had an unusual situation, so we were reaching out to them, saying, Let us know in a very timely manner of anything unusual, whatsoever.
Once we started putting those feelers out, we started getting more and more calls about bomb threats, about aircraft that we had lost communication or radar identification with . . . We had a [whiteboard] on the operational floor, and we used it to put down the call signs of various aircraft that we had gotten reports on . . . We were tracking 11 aircraft that we had gotten unusual information on, that we thought seemed worthy of keeping a closer eye on.
Two of the 11 aircraft were American Airlines Flight 77, which was flown into the Pentagon at 9:41 a.m., and United Airlines Flight 93, which crashed in southwestern Pennsylvania at 10:10. The anomalies that caused controllers to flag the other nine aircraft were explained later to Herndon's satisfaction. We followed up on that, at the end of the day and the following day, Schuessler said. People here continued to say [they had] a little discomfort about the information [they] received. We followed up with the security people and got enough information that the specialists here felt very comfortable that they understood the situation.
One of the nine aircraft was identified in later press reports as a Delta Air Lines transcontinental flight out of Boston. The FAA declined to provide information about any of the nine for this report, however. An agency official said the FAA has no open issues regarding the flights with respect to ATC, but it doesn't know their status in the FBI's criminal investigation of the Sept. 11 terrorist attacks.
Since commercial operations resumed after Sept. 11, major areas of U.S. airspace have been monitored continuously by E-3 AWACS (airborne warning and control system) aircraft and patrolled by F-15s and F-16s.
Schuessler said the nine aircraft involved only a few airlines and, partly because it was not much past 6 a.m. on the West Coast, most of them were in the eastern U.S. Herndon coordinated with the ATA throughout, and officials were on the phone often with airline personnel, people we would typically talk to on a routine basis.
As the reports of out-of-the-ordinary operations grew, Herndon issued a ground-stop order, the first in U.S. history, at 9:26 a.m. No aircraft were to take off. We just thought, OK, enough is enough, let's keep them on the ground and see what we've got, Schuessler said. And then at 9:41 the third aircraft crashed into the Pentagon. We had been discussing various options off and on, the management team here, in concert with the people we had on our telephone. [Immediately after the Pentagon crash], a decision was made to have all airborne aircraft land at the nearest airport as soon as practical, regardless of their original destination, and we also decided to prohibit all international traffic from landing in the United States . . . Shortly thereafter, the fourth aircraft crashed southeast of Pittsburgh. Herndon paid particular attention to the nine aircraft remaining on its whiteboard, to make sure they landed safely.
The ground-stop and land-all-aircraft decisions were by consensus, adopting options that had been explored as the situation developed, Schuessler said. We were pulling all this information together, and it was done collaboratively . . . All these decisions were corporate decisions. It wasn't one person who said, Yes, this has got to get done.
The FAA's 325 en route centers, Tracons and towers, and the air traffic controllers who staff them, did a superb job getting all aircraft out of the sky in little more than 2 hr., Schuessler said. But it was all in a day's work, however extraordinary the day, according to John Carr, National Air Traffic Controllers Assn. (NATCA) president.
At any given time before Sept. 11 there would be about 5,000 aircraft airborne, Carr commented, and when FAA ordered all aircraft down, there were 4,546. The number had been reduced because of the ground stop 19 min. earlier. Airplanes were landing at their destinations during this period, but none were taking off.
THUS CONTROLLERS WEREN'T handling more aircraft than they usually do; they were simply bringing all of them down, Carr noted. They landed them about twice as fast as they would have done normally, but with no takeoffs the numbers weren't unusual. Controllers used minimum spacing and maximum efficiency, Carr said, but we didn't cheat. They broke no rules. With no commingling of departures and arrivals, and no need for en route separation of climbers and descenders, the job was simpler in many respects. Everybody was a descender, Carr said. This was not unlike a very, very heavy arrival rush for every airport in the country.
Considering that controllers hadn't ever tested or trained for clearing the sky, the process was surprisingly smooth, Carr said. The easiest aircraft to deal with were commercial flights that were near their destinations, and general aviation (GA) aircraft -- low, slow flyers, perhaps in the vicinity of the airports they were headed into or out of. For the GA pilots, it was a question of sending an order to land, finding the nearest available and suitable airport, directing them to that airport and bringing them down.
The hardest part often turned out to be overcoming disbelief among pilots, even a few airline pilots, that everyone was going to land. Some GA pilots flying VFR didn't know what had happened.
Another problem was commercial aircraft that were too big for the nearest available airports. It was up to flight crews to determine whether they could land at airports to which they were being directed, and in some cases airline operations people told pilots where the carrier wanted them to land. These factors produced what Carr termed give and take between flight crews and controllers about where to land. There were more than a few instances where controllers had to talk pilots into understanding what they were being directed to do, he said.
Coordination between en route centers, Tracons and airport towers was normal. Whatever facility was controlling an aircraft at 9:45 continued to control it until a normal handoff. Communication between pilots and controllers is no different during an emergency than it is during a normal operation, Carr said. Air traffic control is a very tightly woven net of responsibility. It is not unlike a relay race, with airplanes as batons. Aircraft were passed in sequence from centers to Tracons, to towers, to ground controllers, to gates. It wasn't hard, Carr said. It's what we do. We work airplanes . . . We didn't find it to be even the least bit extraordinary. We found it to be challenging, extremely important, deserving of due caution and care . . . But I don't think you could find a single controller who would tell you they did something extraordinary that day. They did their job.