Nashua, N.H. Before his own plane was hijacked, a United Airlines pilot saw a hijacked American Airlines plane that later slammed into the World Trade Center, a Federal Aviation Administration worker told The Associated Press.
Controllers asked the pilot of United Airlines Flight 175 to scan the skies for the wayward American Airlines Flight 11 after they noticed signs of trouble, the worker said Saturday.
"The controller is trying to determine what is going on, so they call (other planes). One of those traffic calls was to United 175, and he did see him," said the source, an employee of the FAA's Boston Center, about 45 miles northwest in Nashua.
The two flights, carrying 157 people, took off from Boston on Tuesday and crashed into New York's World Trade Center, causing the buildings to collapse in the deadliest terrorist attack in American history. Two other planes were also hijacked, one of which crashed into the Pentagon. Nearly 5,000 people are missing.
The man spoke on condition of anonymity, saying workers at the Boston Center were warned they will be prosecuted for interfering with a criminal investigation if they speak with the media.
Controllers at the center handled both flights after they took off for Los Angeles. The first sign of trouble came about 15 minutes after takeoff when controllers gave the American Airlines pilots permission to move to a higher altitude, the source said.
"The controller, I believe, first knew something was wrong when they tried to clear him to climb to 31,000 or 35,000 feet. They did not respond," he said.
"In some time during that period, the controller notified the supervisor, 'Hey, there might be a problem here _ we can't talk to this guy.'"
All signs indicated that the United flight had not been hijacked yet.
Had the American plane been on course, the United pilot would not have been able to see it, the worker said. In fact, the American flight had veered south around Albany, N.Y., and was headed for Manhattan.
The worker confirmed reports that at some point, one of the pilots switched on a microphone that allowed controllers to briefly listen to what was happening in the cockpit, but he did not know the details of that communication.
A controller at the Boston Center told the Christian Science Monitor that someone in the cockpit was heard threatening the pilots.
"He was saying something like, 'Don't do anything foolish. You're not going to get hurt,'" the controller said.
Those transmissions were the last the New Hampshire controllers heard from the plane, according to the worker who spoke to the AP.