At 8:46 a.m. EDT, American Airlines Flight 11 - a Boeing 767 bound for Los Angeles from Boston that had been taken over by hijackers slammed into the upper floors of the North Tower of New York City's World Trade Center.

TV Stations broke into their regular programming and began reporting on the accident. Details were sketchy and conflicting at first. It was an accident. It was a small commuter plane. One thing was certain by looking at the gaping hole in the building. It was serious.

Minutes later at 9:03 a.m. as news crews were filming and millions across the nation and around the world watched, United Airlines Flight 175, also a Boeing 767 and also bound for Los Angeles from Boston slammed into the South Tower.

At this point it became clear that this was no accident. This was a terrorist attack of some sort against the United States. The nation watched the unfolding drama in horror. Hundreds, possibly thousands were stranded in the upper floors of both buildings. Many leaped to their deaths rather than be consumed by the smoke and fire. Stunned New Yorkers crowded the streets watching in disbelief.

The New York Stock Exchange closed at 9:32 a.m. and five minutes later, at 9:37 the first reports started trickling in of a third crash -- this time in Washington DC at the Pentagon. That was also an American Airlines plane -- a Boeing 757 operating as Flight 77 from Washington's Dulles Airport to Los Angeles.

The Federal Aviation Administration had already ordered all departing flights grounded and they now gave the order for all planes still in the air to land at the nearest suitable airport immediately. Incoming international flights were diverted to Canada. Never had our nation's skies been completely closed to air traffic.

At 9:59 a.m. the horror became even more unimagineable as the South Tower of the World Trade Center collapsed. Rubble filled the streets. The air was choked with dust. New Yorkers ran for their lives escaping the city by ferry or on foot over one of Manattan's many bridges

Before the dust had even settled more reports began coming in that a fourth plane, United Airlines Flight 93 from Newark to San Francisco had crashed in rural Pennsylvania.

At 10:28 a.m. the North Tower of the World Trade Center collapsed. In less than two hours, the New York skyline had been changed forever and a nation lost its innocence.

Thousands of passengers gathered around TV sets at airports, staring silently at images of billowing smoke over Manhattan's skyline, flames shooting from Pentagon windows and people covered with soot running in the streets.

At Dallas-Fort Worth International Airport, hundreds of people were stranded and there were long lines at pay phones as families called friends and loved ones. The nation and the world were in shock.

Not since the passage of deregulation in 1978 had something of this magnitude happened that would have such a profound effect on the future of air travel. There would be changes ahead. The airlines, airports and passengers would all have to adapt. Air travel would never be the same again.