As we move further from that day in 2001, more information is released on what did and did not happen.
“Ten minutes after American Airlines Flight 11 crashed into the north tower of the World Trade Center on September 11, 2001, Federal Aviation Administration (FAA) controllers in New York saw United Airlines Flight 175, heading “right towards the city,” but thought it was aiming for an emergency landing at a New York airport, according to FAA documents released this week under the Freedom of Information Act and posted on the web by the National Security Archive. Minutes later, Flight 175 hit the south tower of the World Trade Center.”
More here.