Security at San Francisco International airport - the gateway to Silicon Valley - has been tightened up with the introduction of CCTV technology which not only observes but analyses footage and alerts security teams when necessary to ensure no potential threats go unnoticed.
The rollout is at the vanguard of improved airport security worldwide in the wake of increased fears about terrorism. But it is far from a simple question of stopping terrorists - it's more an issue of ensuring the airport operates in a secure manner every day, according to Paul Foster, aviation security manager at San Francisco International airport.
Thirty minutes could cost you millions of dollars.
Foster told one of his biggest concerns is around access control: who goes where; and why. And in a busy airport environment it would be too labour intensive to have every door and every CCTV monitor under actual physical human surveillance, he said.
Guy Morgante, VP of services at Vidient which, under a federally funded grant programme, has been providing the video analysis service to the airport, said a major problem with monitoring CCTV coverage currently is with the human sat in front of multiple screens, often divided further into multiple camera views.
Morgante told : "Anybody who has been in a control and command centre knows that is a huge problem. How alert can you be monitoring these cameras for hours?"
Vidient claims its algorithms can monitor what those cameras are seeing and can flag up any suspicious events. Most commonly they are looking for individuals "tailgating" - following another person through an opened door - or static objects, either in secure areas or at kerbside.
Foster said a "one swipe per person" system for passing through all doors is rigorously enforced. The cameras can detect if two people pass through an open door, and can even differentiate between one very large person and two smaller people.
Even staff who are entitled to pass through that door must swipe, in order to prevent an alert being triggered.
And those who do trigger an alert, Foster said, are "admonished" for failing to follow security best practice. "People now know we have a system in place," he said Foster, adding that alerts have fallen considerably after some re-education and admonishment.
The running of a tighter ship therefore makes the task of detecting the genuine alerts far easier.
Asked whether he believes he has ever stopped an incident which could have escalated into a genuine threat, Foster claims that is not really the question: "Did I stop a bad guy or did I just stop an employee from doing something they shouldn't be doing? I can't be certain.
"People in security look at things differently. There is no immediately visible return on investment. You don't see a cash return but what you do see is that nothing occurs. Now, did nothing occur because of the system in place or did nothing occur because nothing occurred? It doesn't really matter which it was. What is important is that we're not dealing with a security incident, and that makes me happy."
Where Foster claims the real returns come are with the obvious non-cashable advantages of running the airport in a secure manner where all staff realise the benefit of doing their bit.
The technology is also employed in access and exit lanes through security checks to spot people moving in the wrong direction and also with traffic around the airport - at secure locations such as the fuel farm. Again tailgating either by another vehicle or by a person following a vehicle through a gate can be detected, even under the cover of darkness.
The Vidient system will also allow for parameters to be set whereby alerts are triggered for vehicles of a certain size, waiting in a certain location for a certain length of time.
If the airport's team can spot an anomalous event and raise an alert to investigate it or stop it proactively then it saves on more costly reactive procedures. A person heading the wrong way through security checks could be lost or could be posing a threat. Either way the outcome could be costly if they proceed and manage to bypass security.
Pointing to the high costs associated with flights missing their timeslots and air carriers having to accommodate passengers, Foster said: "If the TSA [Transportation Security Administration] has to close down an airside and rescreen everyone, then physically inspect the entire airside, there will be a tremendous ripple effect.
"Thirty minutes could cost you millions of dollars."