Here is the report from www.space.com from September 14th, 2001:Dissappearance of contrails at the same time of inoperational commercial jet plane do not means the trails is the works of commercial aeroplane because at that time any other plane also do not fly.
"he International Space Station crew sees them all the time, except when airplanes are not flying, as happened in the days after the September 11, 2001 terrorist attacks. Three days after suicide airplane hijackers toppled the World Trade Center in New York and slammed into the Pentagon in Washington, D.C., the station crew noted an obvious absence of airborne jetliners from their perch 240 miles (384 kilometers) above Earth. 'I’ll tell you one thing that’s really strange: Normally when we go over the U.S., the sky is like a spider web of contrails,' U.S. astronaut and outpost commander Frank Culbertson told flight controllers at NASA’s Mission Control Center in Houston. 'And now the sky is just about completely empty. There are no contrails in the sky,' he added. 'It’s very, very weird.' 'I hadn’t thought of that perspective,' fellow astronaut Cady Coleman replied."
The facts is trails a product from aeroplane, but it is not certain yet if commercial plane is responsible for it.