It is a weak link in a chain in the airport's older terminals that could render all the high tech safeguards useless, putting lives at risk.
The lines, screening and scans for airport visitors can be an unpleasant, expensive and time-consuming experience. But it is the primary safety net for thwarting a terrorist threat.
In some cases, only those with hyper-clearance use hand scan technology to pass from non-secure to super-secure areas.
But just across the hall, inside a public stairwell door, at the top of the stairs, attached to a door, is a security device that defies 21st century technology: a lock and key.
It was noticed by one airport worker who wishes to have his identity protected. He calls the technology "obsolete." He says it's technology that has been around since 1973, and the key that is currently being used is not patent protected or restricted.
That means anyone can get the key in question — called a Best key — duplicated.
The real problem is that the locked door leads to the roof, bypassing all security systems and offering access to many sensitive areas such as electrical rooms, central air handlers, critical valves and electronics — not to mention the most critical area of all, the tarmac.
"Someone could get direct access to a plane by using one of these keys and antiquated lock system," said the source.
The key question, however, who has access?
According to our insider: "One hundred people have access to these keys in just one terminal, and there are at least three that have the old 'Best' lock-and-key system."
That could mean hundreds of keys capable of by-passing security.
Could the wrong person obtain one and have it copied?
The key says "duplication prohibited" right on the head of the key. But it took News 8 less than five minutes to randomly select a professional locksmith who made five copies — including a key that, at one point, was designated as a grand master key capable of unlocking multiple doors, bypassing security at the older D/FW terminals.
In our case, the locksmith never saw the original grand master key; the copies were generated by simply providing a code number.
The D/FW insider says he tried to sound the alarm numerous times before bringing the issue to News 8. "It's been brought to their attention by some people, people who matter," the source said. "People who know what the problem is have asked for action and nothing has been done."
Security specialist Bill Besse of Andrews International says it's shocking to him that airport officials would not have changed the lock cores or moved to a more sophisticated electronic system immediately after 9/11.
"If you've compromised the lock-and-key system, you've compromised a very basic part of the overall basic security system, and so consequently the entire system has been weakened," Besse said.
D/FW Airport officials say this is the first they have heard of a possible weak link in their key-and-lock security system. When News 8 brought it to their attention, officials acknowledged the problem and are promising a fix.
"We've always said passengers and workers are part of the security matrix," said D/FW spokesman David Magana. "They are part of our eyes and ears, and so we would want to know anything that concerns anyone, anything that looks suspicious."
D/FW officials say they want to assure the public there are multiple layers of security in play, and added there is no evidence that these old locks have led to any security breaches or pose any real danger to the public.
That said, those officials have already started to replace and improve the lock system in response to this story.