** FILE ** United Airlines Flight 175 approaches the south tower of the World Trade Center in New York on Sept. 11, 2001, shortly before collision as smoke billows from the north tower. (AP Photo/Carmen Taylor)

Photo by: Carmen Taylor

** FILE ** United Airlines Flight 175 approaches the south tower of the World Trade Center in New York on Sept. 11, 2001, shortly before collision as smoke billows from the north tower. (AP Photo/Carmen Taylor)