The terror attacks 25 years ago this week had enduring costs for America's commercial aviation sector.

Today's domestic fliers are on balance worse off for it, with higher costs, fewer choices, and more delays.

That's because, on Sept. 11, 2001, men who were part of the al Qaeda Islamist terror network bought tickets and boarded four passenger planes out of Boston, northern Virginia, and Newark, New Jersey.

Once airborne, the 19 terrorists hijacked those planes and managed to fly two of them into the World Trade Center towers and one into the Pentagon.

The remaining plane, United Airlines Flight 93 from Newark to San Francisco, was brought down by a revolt of passengers and crew who had pieced together what was happening with the other planes.

The Boeing 757 crashed into a field in Shanksville, Pennsylvania, instead of its intended target, which the National Park Service identified as the U.S. Capitol.

At the World Trade Center, more than 2,700 people died that day.

When Flight 93 went down in Pennsylvania, all 44 people, including seven crew members and 33 passengers, including the four hijackers, died on impact.

At the Pentagon, where American Airlines Flight 77 from Washington Dulles Airport to Los Angeles crashed, 189 people died, including 125 people in the building, six airline crew members, 53 passengers, plus the five hijackers.

For the airlines, the financial impact was awful and bordered on existential.