At 8:48, while the controller was still trying to locate American 11, a New York Center manager provided the following report on a Command Center teleconference about American 11:

Manager, New York Center: Okay. This is New York Center. We're watching the airplane. I also had conversation with American Airlines, and they've told us that they believe that one of their stewardesses was stabbed and that there are people in the cockpit that have control of the aircraft, and that's all the information they have right now.¹²⁴

The New York Center controller and manager were unaware that American 11 had already crashed.

At 8:51, the controller noticed the transponder change from United 175 and tried to contact the aircraft. There was no response. Beginning at 8:52, the controller made repeated attempts to reach the crew of United 175. Still no response. The controller checked his radio equipment and contacted another controller at 8:53, saying that "we may have a hijack" and that he could not find the aircraft.¹²⁵

Another commercial aircraft in the vicinity then radioed in with "reports over the radio of a commuter plane hitting the World Trade Center." The controller spent the next several minutes handing off the other flights on his scope to other controllers and moving aircraft out of the way of the unidentified aircraft (believed to be United 175) as it moved southwest and then turned northeast toward New York City.¹²⁶

At about 8:55, the controller in charge notified a New York Center manager that she believed United 175 had also been hijacked. The manager tried to notify the regional managers and was told that they were discussing a hijacked aircraft (presumably American 11) and refused to be disturbed. At 8:58, the New York Center controller searching for United 175 told another New York controller "we might have a hijack over here, two of them."¹²⁷

Between 9:01 and 9:02, a manager from New York Center told the Command Center in Herndon:

Manager, New York Center: We have several situations going on here. It's escalating big, big time. We need to get the military involved with us.. . . We're, we're involved with something else, we have other aircraft that may have a similar situation going on here.¹²⁸

The "other aircraft" referred to by New York Center was United 175. Evidence indicates that this conversation was the only notice received by either FAA headquarters or the Herndon Command Center prior to the second crash that there had been a second hijacking.

While the Command Center was told about this "other aircraft" at 9:01, New York Center contacted New York terminal approach control and asked for help in locating United 175.

Terminal: I got somebody who keeps coasting but it looks like he's going into one of the small airports down there.

Center: Hold on a second. I'm trying to bring him up here and get you-There he is right there. Hold on.

Terminal: Got him just out of 9,500-9,000 now.

Center: Do you know who he is?

Terminal: We're just, we just we don't know who he is.We're just picking him up now.