This is the easy part:
Detect Active/Passive Wireless Nodes (Core Rules 20th, p229): You automatically find all of the nodes within Signal range that are in Active or Passive mode.
Detect Hidden Node (Core Rules 20th, p228) [First paragraph is about finding a specific node, less relevant] You may instead make a general search for Hidden nodes that are within mutual Signal range. In this case, the test is an Electronic Warfare + Scan (15+, 1 Combat Turn) Extended Test, rather than a Complex Action.
After that, it isn't difficult to send automated messages to Passive and Hidden nodes (excluding the ones registered to your system), along the lines of "In compliance to our internal rules, please turn your PAN to Active mode. If you cannot find how to do it in the next five minutes, security will be glad to come and help you do it."
An active PAN lets everyone see what is in your commlink, and more importantly what is slaved to it. Keep in mind that in Shadowrun, information is power, and having an Active PAN is willingly giving up information about yourself.
So it makes sense in the airport situation: you wouldn't want anyone boarding your electronics-stuffed plane with a commlink full of hacking programs, would you? Or with cyberblades, eyelasers, and ceramic guns subscribed to his PAN?
And given the paranoid nature of most companies in Shadowrun, probably everyone who can do it will request an active PAN, and track the most dangerous targets (or even not allow them to enter at all).
Commlinks are nodes like everything else. Playing a hacker myself, if I could have every node in my environment be active... Oh the dream.