An interim report from the commission's staff revealed a communication failure between FAA headquarters and the Pentagon's National Military Command Center as the attacks unfolded. Poor communication meant the military mistakenly thought American Airlines Flight 11, which crashed into the north tower of the World Trade Center, was headed to Washington, and NMCC was not notified that United Airlines Flight 93, which crashed in Pennsylvania, was hijacked until almost 40 minutes after the FAA confirmed the hijacking, according to a new timeline of the attacks compiled by commission staff.
"The most frustrating after-the-fact scenario for me to understand and to explain is the communication link on that morning between the FAA operations center and the NMCC," said Monte Belger, who was the acting FAA deputy administrator when the attacks occurred. "I know how it's supposed to work, but I have to tell you it's still a little frustrating for me to understand how it actually did work on that day."
FAA and Defense officials testified during the final public hearing of the National Commission on Terrorist Attacks Upon the United States on Thursday.
Belger said the FAA initiated a "hijacking net" at 9:20 a.m. that he thought included the NMCC.
"The hijacking net is an open communication net run by the FAA hijack coordinator, who is a senior person from the FAA security organization, for the purpose of getting the affected federal agencies together to hear information at the same time," he said.
"It was my assumption that morning, as it had been for my 30 years of experience with the FAA, that the NMCC was on that net and hearing everything real time," he added. "And I can tell you I've lived through dozens of hijackings in my 30-year FAA career, as a very low entry-level inspector up through to the headquarters, and they were always there."
Belger added that after initiating the hijacking net, he turned his attention to getting airplanes that were still in the air to land safely.
Additionally, the FAA had military liaisons at its command center, said Ben Sliney, who was the operations manager for the agency's Air Traffic Control System Command Center in Herndon, Va., when the attacks occurred.
"They were present at all of the events that occurred on 9/11," he said. "In my mind, everyone who needed to be notified about the events transpiring was notified, including the military."
He added, however, that the military has its own "communication web," which might have delayed notification about the hijacking.
Defense officials, for their part, said they do not know why NMCC missed out on the hijack net.
Air Force Gen. Ralph Eberhart, commander of the North American Aerospace Defense Command, told the commission that the military has evaluated scenarios since the attacks and determined that it could have intercepted and shot down all four planes if the "FAA told us as soon as they knew" the planes had been hijacked.
At one point, the NMCC set up an unsecure conference call to communicate with FAA headquarters, but even that link kept failing, said Adm.-Select Charles Leidig, who served as the NMCC's deputy director of operations on 9/11.
"If FAA had been in the same conference that was being directed by the National Military Command Center, the information flow would have went directly to NORAD because they're in that conference," Leidig said.
The staff report, however, stopped short of placing blame, and instead praised the response of federal workers who immediately had to respond to the attacks.
"We do not believe that an accurate understanding of the events of this morning reflects discredit on the operational personnel from [NORAD's Northeast Air Defense Sector] or FAA facilities. The NEADS commanders and floor officers were proactive in seeking information, and made the best judgments they could based on the information they received," the report states. "Individual FAA controllers, facility managers, and command center managers thought outside the box in recommending a nationwide alert, in ground-stopping local traffic, and ultimately in deciding to land all aircraft, and executing that unprecedented order flawlessly."