The attacks led to much tighter security and much slower lines at security checkpoints at the nation's airports. Over the years there have been several efforts to have faster inspections for frequent fliers. The latest effort will start this fall.
From the Transportation Security Administration's operations center at O'Hare, officials monitor all the airport's security checkpoints, baggage areas, and roadways. If one of those checkpoints, for instance, starts to get backed up, they can adjust with more screeners.
The TSA is about to launch another broader adjustment to the screening process through a pilot program called "Trusted Traveler."
"So what we're looking to do with Trusted Traveler is move away from a one-size fits all to more of a risk-based system," said Jim Fotenos, Transportation Security Administration.
The pilot program to be started this fall will involve only frequent fliers with Delta at airports in Detroit and Atlanta, and American at Miami and Dallas. Based on their travel histories and backgrounds, the TSA would permit those passengers to go through a faster screening process.
"You're still going through essentially exactly the same screening process if you're a frequent flier, it's just that at some airports, you'll have a separate line," said Hani Mahmassani, Northwestern University Transportation Center director.
Fast-tracking certain passengers through pre-screening has been part of the plan for the last decade. It's had numerous fits and starts.
Four years ago, airline passengers - for a fee and their fingerprint - were able to move faster through airport security, but they were still subject to basic screening - shoes off, lap-tops out. So why pay? the company declared bankruptcy.
There's some criticism that the new Trusted Traveler plan just amounts to a fast lane for a select few.
"I don't want to completely dismiss it, because it is a healthy step in the right direction, that is to start thinking about screening people instead of looking for objects on their bodies or in their baggage," said Prof. Tom Mockaitis, DePaul University security expert.
But what about shoes? Would trusted travelers get to keep them on through security?
"What expedited screening means, whether shoes, laptops, liquids out, we'll determinee over the next couple months as we roll out the program," said Fotenos.
Unlike the previous for-profit efforts, the frequent fliers who choose to be part of this new Trusted Traveler pilot program would not pay a fee, and they would not give a fingerprint or any other biometric. The TSA would use what it knows about them through their travel histories and frequent flier info to build a risk assessment.