UPDATE: Watch full investigation: http://bit.ly/Ppe03f
It's a major gap in security that could put passengers at every airport at risk.
Called the "back door," it lets thousands of people bypass security without being screened.
"They have access to the bags, the planes. They have access to the entire airport," according to one insider.
The ABC15 Investigators first exposed this troubling security gap at Phoenix's Sky Harbor Airport five years ago in an investigation that garnered national attention.
After our report, officials promised change.
So why is it happening again?
We're going through the undercover video that shows the exact the same thing is going on at another major U.S. airport. We also uncovered a shocking Phoenix connection.
ABC15 Investigator Dave Biscobing is putting the final touches on his investigation and will have the full report Monday on ABC15 News at 10.