NEWLY posted audio files depict the horror of 9/11 unfolding in the sky as air traffic controllers struggled to follow the faint tracks of hijacked planes, fighter jets tried in vain to chase them down and a flight attendant made a desperate appeal for help.

Newly posted audio files depict the horror of 9/11 unfolding in the sky as air traffic controllers struggled to follow the faint tracks of hijacked planes, fighter jets tried in vain to chase them down and a flight attendant made a desperate appeal for help.